618T-3 HF collins aircraft radio, k0ip, collins military radio, 618T-3b, 714e-3, AN/URM-157, MRC-108 jeep, mrc-95, 426T , 488A-2, 490t-1, maintenance manual 618T-3, MRC-117, mrc-108 military HF , forward air control radio
Collins 618T-3 Aircraft Radio  - Ham Radio - k0ip  K IP
 618T-2 page   A work in progress.                   and the ARC-105 page

This web's a collection of Books, Schematics, useful info, supplied by various 618T users,
When I was building my 618 system I had to search here & there to find information. Somewhat frustrating at times, So I've tried to bring it all together in one place.  once I started then many of you (HAMS) send more documents.
How Good can it get,  hams helping hams.  keep that info coming, ur pictures too.

NOW, if you see something in ERROR, Please let me know so I can fix it ..

If you have any updated,  PDF's of books, personal stories,  or have any 618 and related equipment for sale , or
know a source of 618's, parts and pieces and accessories  please send me the info so I can get it on this web.  
my email is k0ip((at))k0ip.com   call 208 251 6441

FYI: There's a Collins 618T  User Group !!!  
A place to get answers, stay in touch,  and give help to others.   https://groups.io/g/Collins-618T
This user group is a great resource. Lots of experienced radio techs ready with answers,,   all the manuals and
more.......  sign up today.......... 

Fellow Hams,  especially DX visitors to the USA,

If your in the area of Yellowstone National Park.
Stop in for a Visit

My home in Pocatello Idaho is just off exit 69
interstate I-15,  one of the main routes to Yellowstone, Jackson Hole & Grand Teton National Parks.

Stop by for a visit & some local Pocatello flavor.
I would love to meet you. Have an EyeBall
QSO , you can get out of the car and stretch, have  a
drink, coffee, beer, etc - maybe more ?  your invited

try to give me a Heads Up -- if possible call or write.. Otherwise just knock on the door.
tnx John
k0ip((at))k0ip.com  call 208 251 6441

KIP's home page    --            Join me on Linkedin search john wilson k0ip

if you have any knowledge of the 117 radio set  , ok, your Not sure what a 117 is ,, CLICK HERE
please contact  wa0dyu(*)gmail(d)com  or k5urg(*)yahoo(d)com   or w1nzr(*)cs(d)com
Here are books we are desperately looking for






All Email addresses on this web have been modified  to prevents Robots from harvesting them from this web.  protecting me and you..
Note:  if you see  (*)   in an email address,
you need to change it to a @. and close any spaces, emails have NO spaces.  (d) is a  period 

NOTE: Most Pictures on this page can be ENLARGED by clicking them !

Want some Fun ?? 
Here I am screwing with the minds of the CCA Net control station
on the Sunday 20 meter net. some of them are very interested in my
strange sounding collins radio,  but many are just semi-confused about
anyone using a WW2 carbon microphone ,,   say what , Carbon  ???


Warning: I am not trying to tell anyone that I am an expert, I really have little knowledge about the radio's internal circuits, other than what I can learn from reading the instruction books and schematics.  note there are many experts on the user group listed above !!

I first saw one of these marvels when I went to a MARS convention in St Louis MO, in the early 60's.  I was still in high school, and a new ham...  The Collins guy had a wire out a window and was dialing in frequencies and talking with Cedar Rapids (?). This freq, then that freq, then another, it was like magic WOW what a radio. 
If  your old enough to remember. I had a 20A using a ARC-5 command set VFO....
I never thought much about  getting 618T on the air, until my friend Math ON8PO convinced me I should do it.
(see his private military radio collection at this link  ON8PO  Truly amazing ) 
So I did, now I have two working units, one being the MRC-95 jeep configuration. 
I'm now looking for a 24 volt jeep at a price that doesn't break my bank
account or my marriage   .. HI HI 

There are 3 versions of this radio,
none of them are very user friendly as far as the power requirements! 
From what I know,  the T3 is the only model that's easy to get  power for,  its mostly brute force 24VDC (see below 24VDC)  and a small amount of 115V/400cycle. However,
I have received letters from folks with large 400cycle motor-generators 
powering other 618T versions .

The 400 cycle power is a problem, but nothing that can't be overcome. see below 400Hz
Be careful what you buy, I bought a  516H-1 thinking would make 400 cycles, it doesn't !!

For a  618T3 What do you need:
A big 28Vdc power supply and a 115Vac 400 Hz supply. the proper control box.
You can use the interconnect diagram and make a wiring harness.
If I had it to do again, rather than using the URM-157 Test Harness as a control box,
I would  have make a 19" panel with the control head and
whatever controls / jacks I needed. Something like this picture would be deluxe !!

This 19" control panel is sure sweet, it looks like a Collins product, I don't have a
part number, but just maybe there are some of these floating around out there in
radio land somewhere ?????  Keep your eyes open at flea markets ..

Picture from VK3XAO











































These books are provided free for Amateur Radio use only.

this book provided by  Luke AC5XP, Is the one to start with, and maybe finish with !.  It has horizontal schematics, it appears to be the complete with addendums up to APRIL 1979. 
THE LATEST, it is easy to read, the file isn't too big. very professional.

Collins 618-() Overhaul manual 15th Rev. Oct '79 optimized.pdf (13mb)

" Must have Schematics "
TM_116625-622-40.pdf  URM-157 with schematics
(very useful  in running down where wires should connect, even if
your not using the URM157, See pages 37 and 38 for the two models
of this test harness . The one on page is for the 618t  B models..
(See pictures and description of the two units ,  down this page)..

618T-3 Interconnect with 180L-3
(Very Useful, in running down wires)

This is another , "MUST READ"  
618T sales propaganda book  especially the last few pages,
which describes the radios various configurations, and accessories..

426T1 400Hz power supply book
488A  400Hz power supply
(note: the user group has lots more info about these power supply)

ARC-105 info page LINK  from VE6ABW

490T-1  & 180L-2  & 180L-3A  & 490T-4  Antenna TUNER INFO Page

Manuals  below are linked to the Collins Collectors Association web, 

618T-x_Maint_Parts_Tools TM 11-5821-248-34P  (CCA_Download)
(ARC-102, Not very useful)

618T-x_Gen Maint_Parts_Tools TM 11-5821-248-20P (CCA_Download)
(ARC-102, Not very useful)

618T-x_Gen Maint_Parts_Tools TM 11-5821-248-12P (CCA_Download)
(shows part placement in radio)
These are older manuals   , 1962 - 1973 - 1978 ,
 it would be better to download the book at the very top  of this list  

618T-x_Maintenance Manual_Rev 1 15_Jan 1962 (CCA_Download)
(complete Book for 618T 1, 2, 3)

618T-x_Maintenance Manual_Rev 13 15_Aug 1973 (CCA_Download)
(complete Book for 618T 1, 2, 3   PLUS the B models)

618T-x_Overhaul Manual_Rev 15 Oct 1978 (CCA_Download)
(says it covers the T1,  through T6B )

618T-x  only Schematic Diagrams (by AC5XP) (CCA_Download)
(just schematics)

618T-x only Horizontal Schematic Diagrams (by JA6ATY)_ (CCA_Download)

618T-2 in the C-141 aircraft (CCA_Download)
(in-depth discussion of modules, how it works)

CU-168_FRR Coupler TM 11-5985-212-15 (CCA_Download)
(this is an obscure multi antenna coupler, not useful)
from PA3ESA ,
Webmaster: probably better to start with the manual listed at the top of this list,   
The A3 and A4  refers to the paper size,, which needed to be scanned separately ...

A4 maintenance and install manual.pdf   (webmaster says hold off on this one (70mb)     
A3 maintenance and install manual.pdf   these are just schematics   (13mb)

A3 Wiring interconnect. pdf          (6mb)
A4 Wiring interconnect.pdf           (10mb)


And this book,  covers the 618 plus many of the test equipment. in some detail.
this download is (32 Mb)..  Navy AN/ARC-94_navweps.pdf    
Also here are two book that cover parts of the AN/MRC-117 / GRC - 158 Radio.
SEE GREEN BOX at top of this page,,  WE NEED other manuals, can you help

MRC117_TM 11-5820-676-12.pdf   (47mb)   
for the FILTER , which could have been used in other radios too ???
MRC117_Filter_F-1138_GRC_EXP.pdf  (35mb)
Now here an interesting Collins sales book , covers all (?) HF equipment in the mid 60's
Collins-Communications-Equipment-1965 (7mb)

here is a page with info about the French 618... ER-104-A
from PAPLT



possible sources of radios, and parts
 Murphy's - BPB  surplusColumbia Electronics international
William Perry Company 502-893-872

-- Ebay. - 

for connectors check  Lasaero UK -  
look towards the bottom of the page.

For Sale Area.    & Wanted            for personal sales only

Personal Sales Page
Some of the equipment that is presently be listed on the personal sales page
click the button, for a better description and some pictures.

These listings are free, if you have something for sale, let the webmaster know.




OK Guys,   Luke AC5XP  has a great video on YouTube  that explains this radio.  A lot of info about all the modules, and power supply options.. ++ more


For more info about the power
requirements for the 618T-2 Please
see the  618T-2 page ..  the 208V isn't completely clear, it depends where you measure the voltages, ,  read the T2 page.

Collins 426T-1 400 cycle power supply, this supply is used in the MRC-95 
This is rated at 115Vac Square wave, 400Hz, 630VA 
426T1 400Hz power supply book

bigger view, Front   Back


Another Collins inverter, made for
the 618 is the 488A-2

488A  400Hz power supply book

one interesting thing: this supply plugs directly into the 390J-2B rack
(shown below, see racks)


also a T-195 Dynamotor will probable work if its all you can find, as might other dynamotor type devices .


this  400 cycles Supply
DOES WORK, in use
its only rated at  150VA ??
$49 at Murphy's

from a reader of this web page

A source of a 400 cycle power inverter is the PP-2352 that converted 28V DC to 115V 400 cycles.   They were used in the Jeep Transceivers.

73,  Bob  -  W0RY

And this GREAT 400Hz project
from Takashi JA6ATY
who powers his 618T with a modified
 12 Vdc to 100Vac Car  Inverter.  Link

Tested and working !!

Here's another one !!!        click for a better picture

This is a C.F. Electronics  700VA power inverter, part number 200810..  
This along with the EKCO E182 (above) must be direct replacements for the 426T-1 collins inverter.. SAME plug and same size. 
 click here for  TO in PDF        supplied by WGZV     w0gzv texas

400 Hz power supply project

Take a look at F1FRV web,

or this link for a download PDF
Thanks F1FRV  --  F1FRV web

24 VDC supply

One possible recommendation:  shop Ebay for a Lambda
LRS-58-28 ..       LRS-58 model..   Shop the "Auction's only", for
better prices..

a note from a 618 owner:  I have this power supply  running at 25
volts, it just sits there quiet as a mouse even in TX Tune mode.  It can
be turned up to almost 27 volts before its internal over-voltage
protection circuit trips.

Here's some info i grabbed off the "group.io"

I found this on eBay: https://www.ebay.com/itm/184645036684?var=692365815317 

It can deliver 62 A peak (at 24V). I felt the price to be fair, so I ordered one. It arrived well packaged, and pretty fast for a China order; within 3 weeks. Turns out it works great with the 618T-3 radio

Quality of build is excellent. It is a 24V PSU but there is a trim pot on the right side of the terminal (barely visible on the photos) which allows you to adjust it to 28V (which the pot reaches without a problem with room to spare)

It is specified for 62A which might be a bit less when tweaked to 28V, but I can now modulate my 618T-3 fully (delivering 430 watts PEP in SSB) without the DC voltage dropping in any way

They sell two models, 100-120V AC and 200-240V AC, which means also good for use in the UK (assuming you order the right model of course)


webmaster comment:  I went to the link on the left for these supplies and only found a few,   I had to look at several auctions before I found one that runs on 120VAC  ..   
I suggest you search for  

AC DC 1500W 12V 120A 24V 60A 36V 40A 48V 30A Industrial Switching Power Supply

NOW,,   if you view AC5XP's video, he says these are fairly RF noisy.
and suggests a PULS SL-20. 

continued just below


So AC5XP uses 3 of these in parallel,  to give him 60amps
they are adjustable to 28 VDC  and Luke says they are RF quite..
I looked these up on ebay,  the prices are ALL over the place,
some as low as $75 each to hundreds each..
these are PULS  SL-20   supplies,


Control Heads

Control Head, be sure to read  "618T sales".  You can learn a lot about the correct parts and pieces for this radio.
There are lots of control heads on Ebay, most are priced "out of sight".  If your in a hurry, buy a good one, otherwise
I say, take your time and keep looking for one at a reasonable price.
This is the 714E-3 Control units, I am not sure how it differs from the C-3940/ARC-94 (to the right) it looks the same on the front .

There appears to be a wide variety of various part nr.
another slightly interesting item , a test set for these heads
ASI-162  link  on web link  anyone out there have a real picture of this test box ??
Military heads that works  .. click it
There may be more heads that work , however, this is the only ones I know about .  C-3940/ARC-94
Click Front or Back view ,
here's a picture of the front and back of the
714E-2.. (commercial)  it has a different connector than the Military units. click pictures to make them bigger.. note lack of CW and Data modes 

pictures from K7APO
This is the 714E-6.  It' s for the
Note the 100hz digit

Click   Front  or  Back view, bigger

Getting the plug for the back of the Radio?           THIS is a major problem !!!!!!!!!
When I built my radio setup, I could have attempted to purchase the female plug for the back of the radio, but I wanted to sit the
radio in a rack, so I purchased a brand new retro-fit rack 49-T4.  This "retrofit"  trick is used so the
aircraft Weight and Balance doesn't need to be recomputed. and the old aircraft wiring works.
This saves the aircraft owner a lot of money.

the female that mates with the radio,
Cannon DPE-60-33s,  a 60 pin connector. you might check for
Here is the female that mates with the commercial (?)control heads ,   
at least the 714E-2
the female that mates with Military control head, Cannon 20-39  (at least that's what mine says) the female that mates with the 426T-1 400Hz supply ,   Cannon DPX-32-02-339

bigger view

Looks like Amphenol  4 S81 ??

bigger view

bigger view
NOW,  for the URM157 test harness
the DC and 400hz AC plugs. 
My URM157A has a 5 pin plug for the DC,  however it appears that most 157's only had a 4 pin connector ???

 make sure you know what you need
AC in 4 pin Amphenol

DC in Amphenol
The 18-4S connector is Mouser part number 654-973106A184S
The 22-22s connector is Mouser part number 654-973106A2222S

I like EBAY, shipping is always a killer to overseas locations, 



if you have more info about plugs or any of these numbers are found to be incorrect, PLEASE let me know.
note: some of the companies I have listed above, to the right, sell these plugs,  HOWEVER, I think they are thieves, asking $200 or more for a connector !!
if you find the 60 pin connector for $50 to $100 dollars, that's probably fair,  any more and someone is trying to take advantage. If you discover a source that's fair
buy them all,   I bought 7 of these for around $55 each, and sold them on this web for my cost + 10%, , the six were gone within a few months. now I have a free spare for my
next project !.  Note:  I only have one spare, I don't horde .


note: the 618t must be elevated , as forced air escapes from  the bottom of the radio. 

49-T4 Retro fit rack




Note this looks like the rack below,  but its not,        needs external 400hz








This is the 49-T4 Retro fit rack .
Note: the WIDE sides..


390J-2B PART 622-1253-001
click the picture to make it bigger you can see, on the top, a small connector
that mates with the 488a-2 inverter. 


This was listed on Ebay as coming out of a Helicopter

TEST SET's   Proper name  "" Test Harness, Radio set AN/URM157""

Please NOTE:   These are great to have,  There are 2 different configurations,   the older units,  on the left has a toggle switch to select the type of control head, it does not work 100% with the 3B model radios,  it works except for the 100 Hz switch.  there are no wires connecting  the 100 hz switch.
The unit (right)  has a rotary switch (bottom row of connectors and switches)  IT does include wiring needed for the 3B radio.  IF  you get the entire test set, it comes with all the cables needed to connect all the 618t parts and pieces together.  SO other than needing the Power Supplie(s)  you've got what you need  to get on the air . 
Note: many of these sets have been scavenged for the cable that goes between the radio and the Harness.. Look Out when buying
AN/URM-157 (Test Harness) 

higher RES view,  Another hi-res view 
note: The URM-157 test set is for all three 618T models, I've heard that selecting the wrong radio might cause smoke ??  Probably nonsense ???  But as with everything, be careful to plug the radio into the correct connector, and select the correct radio & control head before applying power
  (Test Harness) later version TS1949A/ URM-157A  
This unit works with all 618T-x versions including the 3B and its 714E-6 head.
Note: rotary switch in bottom row, it selects the type of control head to be used.
also, the cable is labeled 714E-3/6  so whether this cable works with the E1 or E2
heads  is an unknown .
Heres a PDF that covers both models  TM_116625-622-40.pdf  
  a bigger view of this picture  ,   front controls close up,   top plugs close up.
Collins MK-722A/URC Test set,
it has extenders for the 618 modules..        
 pdf  MR-722/URC maintenacne kit.pdf
<--       click me to make me      bigger        -->
heres some pictures    one  two  three  four

618T-3B  Late production commercial units
The 618T-3B model does 100hz steps,   It has a different synthesizer.
The 3B was introduced at the end of the 618T's production and was only offered for commercial service. 

Since the 3B radio was never offered to the military, the military AN/URM-157 (Test Harness) is not wired to accommodate 100Hz steps even if you
have the 714E-6 head.  The military test set only test the 714E1, 2, 3  control heads, which are  not all  wired the same ! make sure to select the proper head.
Please see discussion about various URM-157's just above....

the 618t-3B has  4 extra connections that control the 100hz steps
   W on the head  to  20 on the radio ,       X  to 21 ,   (lower case  k ) k to 22,     (lower case j )  j  to  23 .

a 618T-3B it will work using a 714E-3 head, however there are NO connections
for the 100Hz control wires.  If you just let them FLOAT you will be off frequency.
There is a matrix in one of the books showing how the 100hz switch works,  none of the possibilities are all open
I suggest you ground  radio pin 23  and leave 20,21,22 floating,   this sets the 100hz step to  zero  


(note 1) looking at the interconnect diagram it's a little hard to make out some of the pin numbers  !!
here is a picture of the connector that plugs into the back of the control box as well as a picture showing the radios pin out..
some confusion:  the radio plug pin 24 goes to ' i ' on the control head .
it looks like there are 2 pins that are labeled  number 16 --   NOT so,    16 is to the left of 4  and   18 is to the left of  60, look close

Note: the pins on "this diagram" and the pins on the
"interconnect draw" are not in the same ORDER  ,,, Heads up !  don't get confused

OK, Guys,  be careful, some of these designations are confusing,
The  "wire"  designations are not the same as the PINS on the control head connector   !!

here is  3 different views of the same thing
1. <--- to the left,  is the radio connector
2. below is cut from the TM_116625-622-40.pdf , listed above under BOOKS
         which contains the complete diagram of the Test set, it is very helpful.
3.  618T-3_interconnect_

click to enlarge the picture       This is the control box connector
for the Military

This is the plug that mates with the military control head

THIS is the connector for
the (???) commercial 714E-2 control box,
No bigger pins and a completely different metal shell.
click it to make it bigger
















Other Webs with 618T information
* from a British group, which you can find if you just google     collins 618t    some good info  heres a link to their PDF

* look down this link for the "618 overview"  http://www.austradesecure.com/radschool/Vol32/Page5.htm  by VK3XAO
      he has some interesting pictures of a base station rack.

*ARC-105 sales propaganda sheets Plus More    The ARC-105 is a pressurized 618t for use in military aircraft,

* an/mrc-95 forward air control system  http://www.afdasf.org/dasf.html   pictures are listed in sections by the guys that took them,
   Lots of great pictures of military life, some of radio jeeps,  but you have to spend a lot of time looking.  it is the source
   of the information about the MRC-108 Jeep  is  KV4AL 

* PA3GON  several military radios and other information.        http://www.aviation-radio.com/

* Info I found from F6BIR,  its all in French , looks like a home brew 24 V and the 400 hz supply check it out

*. more pictures of the MRC-94,  MRC-108 & MRC-107  link 1  2  3  4

* Interesting site: F1FRV has a LOT of info up about the 490T1 antenna tuner, pictures,  downloads 
   covering everything about the 490T-1
and the ARM-109 test set  and info about a 400 hz supply , plus some of his home
    brew  interface units ,,    

                        Here is a list of non-618t webs about things I find interesting !

*  Almost anything military   ON8PO  pictures   http://www.mil-com.be/

* Crypto Museum, This site has a LOT of info, almost too much to digest, very fascinating..   http://www.cryptomuseum.com/ 

* Need info about a lot of military radios,   got something to share with these guys ??   http://radionerds.com/index.php/Main_Page



MRC-108  ROMAD , Forward Air Control Jeep,     click the pictures to make them bigger

More pictures and information about a restored jeep at Wright Patterson National Museum  USAF.

picture by Robert Michael  link go down to 4th DASF  or


H.F. Transceiver was a AN/MRC-95 by Collins Model Number 618T3,  718F-1 coffin, 313V-1 control head, 618T-3 radio, 426T-1 power inverter,
460D-1 load coil, 670D-1 tuning coil,  76F-3 speaker.  The HF Antenna was 32 feet tall mounted with a rubber boot for protection to people passing by so that
they would not receive RF Burns
.  This antenna reduced to 10 sections the width of the jeep. This antenna is a Shakespeare 120 HF Antenna,
NSN: 5985-00-846-6442 Military nomenclature: AT-1011/U  and is still available from the factory in South Carolina.  
Here's a
link to a nice picture and complete radio run down, by Capt. Burt Blatter.   their home page

first two pictures are pulled from http://www.qsl.net/ik0moz/admm_intern.htm
more pictures of this configuration at http://www.hypertools.com/pix/pix.html  (down the page )

click for a better picture   VC-102 HF communication system



AND NOW here's another one,
the AN/MRC-117 as used with EusCom Command Network in Europe from 1976 to 1984 .

Click,  here's a story ! from an actual user of this system  ,,  WA9Z

here is the only TO I have on the mrc117,
its only covers the mechanical mounting to the truck , no electronics  
TM 11-2300-370-15-1.pdf 
                                                                 DO YOU HAVE a book ??  please contact me .

Below are some pictures of the control head used in this system , 
more pictures and a story  see LINK
a note from WA9Z ,   Is this thing cool or what?!!
It mounted on a pedestal between the front and rear seat. There is (was) a removable cover on the control head that had a compartment to store audio accys, pens paper, etc.
There were privacy curtains on the rear windows and between the front and rear seats, and red lights for cab illumination. The operators had a small desk to write, hand microphone, 2 headsets. and a J-38 on a leg iron. As you can imagine, pretty cramped quarters.
Every time a truck deployed the head was installed, and removed when the truck was motor pooled.
As such, I spent most of the time repairing the plugs and sockets.
Haven't seen one of those since 1979. My research leads me to think there was only a few hundred of these ever built for the Pershing II  quick reaction teams.    

click it to make it bigger


more pictures and a story 
see LINK

click it to make it bigger








In the AirForce,  these radios were used in so many aircraft, I don't know if I could list them all,  plus I don't know them all   !!!
but for sure the C-141 ,  C130, 
Also Civilian aircraft,   707's to the Concord


IN THE NAVY,,?   do you have any pictures or info about Navy installations..  please send to webmaster,, tnx

HELP SECTION , WE have questions
anyone have any ideas or info,,   these look like the MRC-95 control heads But they are Gray,  indicating NAVY ?? ,
these two boxes  have slight differences.
Do you know what radio this type of control box was used for ???      take a look there is a difference   something to do with filters,
                            313V-2                                     and                                313V-2A
here three PDF's to help with this control boxes,,     313V-2 Manual.pdf            313V-2 Schematic.pdf      313V-2  Test Set.pdf


Fast Patrol Torpedo Boats / PTF-17, click pictures to make them bigger
 note the big whip , mid ship,


More info link  N6CC 
TSQ-108 mobile radar station,      
the Navy TSQ108...Mobile Inshore Undersea Warfare Unit 1920 sets up the AN/TSQ-108 Radar Sonar Surveillance Center (RSSC) van at Mare Island CA. Keeping watch a training exercise circa 1980.
Radar, sonar, sonobuoy receiver/ recorder system, VHF R/t x2, and 2 each 618T-3 in a "hut". and 2 whip antennasthe tuners were at the antenna.
better pictures

More navy info, from David Stovall
I used to work on them in the Navy and got a job after the Navy because I could repair them. 

The ARC-94/RT-618T2 was used in the P-3 Orion while the

ARC-102/RT-618T3 was used
on the SH-3 Sea King
and the

ARC-105/RT-618T1 ( it could have also been called: ARC-105/RT-712) was used on the EA-6B Prowler.
I have no pics because I'm pretty sure that would have gotten me courts marshaled.
I still remember some about them.  Because they use mechanical tuning, they scared a lot of
techs into believing they were more complicated than they were.  Most of the time when a transceiver came in to the AIMD
(Aircraft Intermediate Maintenance Department),  they weren't so much broken as badly out of tune.

Anyway, if I can be of assistance, shoot me an email.   ddstovall((at))charter.net
David Stovall
SH-3 Sea King        ARC-102/RT-618T3

EA-6B Prowler       ARC-105/RT-618T1

P-3 Orion                 ARC-94/RT-618T2
In the Marine's
Here's a letter received June 2019
Hi. My name is Ray Fellows. I live in Midlothian, Tx, just south of Dallas-Fort Worth. I ran across your web page and it sparked up old flames.
I repaired these radios while I was in the Marine Corps, around 1999 to 2003. I repaired more than my fair share of them. 
When I checked into my command after school, there were 22 of these radios waiting to be repaired. No one was working on them,  no one knew how.
I took it as a challenge. I dedicated my time in the Marines to HF and no one messed with me. I worked religiously learning as much as I could. After about
a year, I had all of those radios fixed. I got orders to Okinawa for 6 months. When I got there the SSGT (boss) asked me what I worked on. I said HF. Well
I inherited 17 more radios to repair. I got so good a fixing these things. I would read the theory of operation and study schematics on my free time. I can recall
being so excited when I found out how to get the 3.5 Mhz oscillator to finally lock. I ran to a friends room in the barracks, barged in and hollered its the Kstab.
You have to align the Kstab first! They thought I was nuts and I suppose I was. 
I attached some pictures of photos my mom took of me when she came to visit our shop way back when. I still have all my old notes, procedures, schematics.
I was so passionate about these radios. I sure do miss them. 
I am an electrical engineer now at Texas Instruments. When I saw your page, I immediately began searching for a radio on ebay. Nothing yet, but when one
comes around for the right price, I am going to snag it for sure. I obtained my FCC General Radio Operators License when I was in the Marine Corps. I
suppose if I wanted to talk on a 618 I would need a bunch more, antenna, control box, coupler?, power supplies, etc.

While in the Marines, these radios were referred to as "94's" or "102's". I am sure you understand the references but AN/ARC-94 used the 27.5 Vdc power
supply and the AN/ARC-102 utilized the 115 Vac 400 Hz supply. The first squadron I was in supported helicopters, the CH-53 and CH-46. The "94" was installed
on these aircraft. The second squadron I was in supported CH-53, CH-46, and C-130's, among other aircraft also. The  C-130 used the "102". It was important
to make sure when you built a radio that if you were filling a 102 hole that you remembered to update the keying in the back of the radio or it would not plug into the aircraft, ask me how I know. 

heres RAY,, at his work bench,
CH-53E heavy lift helicopter
Sorry Ray, I couldn't find a good shot of a Marine 130
this one belonged to the USAF

Possible First product review ??        Collins Signal Magazine 1960.
click to enlarge .



How about an AIR DROP ??
click to enlarge

Heres some interesting pictures from the collins PULSE company magazine
some interesting reading,  lots to look at see http://rockwellcollinsmuseum.org/collins_pulse/index_a-z.php#6                   

click to make it bigger, 
1. MRC-108's  all in a row   
 2. 618's on aircraft 3.  see Collins Canada, click to make bigger


Hams in Action
Operational 618T's    Hall of Fame !! 
     send me your pictures  and letters                            One left click on most pictures enlarges them !

KIP - The guy that runs this web !!

The 618 is almost visible in the lower bottom , right rack Now for you 618T folks, want to drive the Collins Collectors assoc
net control stations crazy,  most of whom are S-Line  operators,  worried about their D104 mike audio...
check into their 20 meter Sunday net with your airline quality audio.. carbon mike, sparks some interest..  
OK, to be fair, some of them are interested in your strange radio,
but most just think your crazy..  give it a try..
?? want to gang up on them,  email me your intention and I will meet you on the net ..
I seldom check in. I live in 7 land and by the time they get to me
I'm asleep at the switch. 
and the entire rest of the country has switched Off their s-lines

ON8PO - shown with antenna tuner , home constructed box for
control head and mike and earphone jacks , in a nice transportable display

One left click on most pictures enlarges them !
On the right a 618t that I have build into a case so I could take it with me at field days, 400Hz is generated by the black box inside the case on the right.
On the left you see a MRC-95 that is based on the 618t with the 426t 400Hz inverter.

Some detail of the homebrew transportable 618t

  Front of the AN/MRC-95

Internals of the AN/MRC-95



Here is a picture of my test set-up.

I am using a 40 Amp Lambda switching supply for the main 28 volt dc source. The 400Hz inverter is driven by a separate smaller linear supply. I built a panel to hold the control head and other switches and jacks. I have ordered .050 aluminum to make side panels and will eventually make a mount to hold the radio. Here is a picture of the test set up, all mounted on a cart for easy access in the shop.

This is really a great radio and meets the requirement that "real radios have motors".

Many thanks for  all your assistance. My next step is to get the operational level to the point where I can check into the local 40 meter AM net

73's Geo.

some comments from Leighton GW3FSP::::: Hi John
Just thought I would let you know the 618t is not dead here in the UK !.

I worked for British Airways until I retired 2 years ago, about 2 years before then I was given a 618t complete with all the mounting cradles, cabling,
control heads, 180r tuner and control system, spares and all the test equipment ( extender units etc ) when BA no longer had any 618t sets in their fleet,
these were fitted to the early 747 ' Classic ' or 747 - 100 a/c and of course the Concorde aircraft, it was originally fitted with the 3 phase 400hz 115
volt ht supply, however I managed to pick up one of the 28 volt supplies from Ebay, ( The A8 module, )

The radio I have will tune to 100hz, so I had to add the extra control wires from the mounting frame to the control head, to get the tuning to work down
to 100hz, I also had to modify the power supply wiring on the mounting frame to allow the use of the A8 power supply and also fit the extra wiring inside
the 618t for the 28volt dc supply, I was also lucky to ' acquire ' a 7amp inverter supply unit from the same source, this is an ELGAR inverter supply unit
which supplies ac from 10 hz up to 1000hz at 7 amps. this I use to supply the 400hz 115 volt supply to the 618t.

I then bought a 42 amp 28vdc switch mode power supply from Ebay which is used  to float an ex aircraft nickel-cadnium 28v battery
( again from BA ) when the radio is in use, it takes a good 38 amps so I'm told when on TX.

And after squeezing the whole lot under my shack bench - it works !, and I have to say it works very well!, rx is very quiet with almost
no internal noise, the noises thing with the radio is the little cooling fan mounted in the front panel for internal cooling which revs up when on tx.
and howls away merrily, it really warms the shack after running the set for about an hour, on ssb I get excellent reports of speech quality using
one of the Seinhauser aircraft headsets I also ' acquired ' with a little whine audible from the 28 volt inverter supply on tx audio, apart from that
I've had no adverse reports .
Hope you are enjoying your hobby, I know I am. 73's Leighton Davies GW3FSP        ps I'm in QRZ.com
some comments from Bob  K8RJ about his radio ::::Just stumbled across your very interesting page on one of my most favorite
radios. Lots of super info. 
I am Bob K8RJ, started as K9ITS in 1957 in Chicago , spent 18 years out in Orange County California and now live in Michigan's UP.
My first 618T-3 was one that I obtained in a government auction back in about 1967. At the time it was just a black box on a pallet full of
other surplus stuff. Back then when I had the need for manuals I could go to the Great Lakes Training Center library as a civilian. Lots of things
have changed since then, this is no longer possible. Anyway. all I knew about it at the time was it seemed to have two 4CX250s and their
sockets and I was thinking of nice linear material. I nearly fell off my chair when I read from the manual what it could do!  

I was hooked. At the time with a wife, three kids, a mortgage and a full-time job at which I traveled a lot I could not afford the real Collins
control head or power supplies. But, I did spring for all the Collins manuals and set about getting my 618T-3 on the air.

Back in those days there were many  electronic surplus outlets in and around Chicago. I managed to build a brute force 28VDC supply using
several huge high current filament transformers with wired series/parallel secondaries, got some 200amp diodes and some computer caps for
filtering. For the 400Hz at 115VAC I started with a rotary inverter --- nasty!!! Then I lucked into a nice SS inverter at a hamfest to do the job.

Then, I could not afford a real Collins control head by a long shot. But, I had access to many multi section rotary switches at these surplus stores.
So, I decided on a Nixie freq. readout and display. I built the display into an old Heathkit defunct Hi Fi amp cabinet that I bought at a ham fest
for a buck. I had to buy the actual switch section from Collins for the MHz codes and Nixie display. I wired up the other switches to do the
needed codes and used a separate section on each switch to light the Nixies. Lotsa dollars for those Collins MHz switch sections; but much
cheaper than a real control head. So, I wired the whole thing up and it worked like a charm. Looked great too. I'll bet the ONLY Nixie readout
control head for a 618T-3!!!

Eventually I figured out why it likely was surplused out by the Navy. It would only transmit for a couple of minutes then drop off the air. I can
imagine that it worked well on the bench then on the aircraft it would drop out, back to the bench and it worked well, etc. So, I scouted around
the surplus stores until I found a suitable relay and it worked perfectly with that one for many years. Eventually I sold the entire rig to a local ham
who just had to have it and who had deep pockets . . .

A few years ago I got the bug for one again now that I am retired. I bought one from a ham in Washington State. Obtained power supplies and
a 714E-3 control head. I found the test set at Fair Radio, some power cables and the test set to radio cable with the 60 pin connectors at each end
from a surplus dealer on the internet.

Much to my disappointment when I put power to it, it was DEAD DEAD DEAD!!!

Did some checking and found that the 18VDC power supply was at zero volts. I eventually found the problem to be a shorted electrolytic cap in that power
supply. A $1.20 repair part. BUT, US parts suppliers wanted upwards of $10 for shipping of this little item. So, I checked on ebay and found a lot of five of the
exact same caps listed by a seller in Rumania -- American made new Kemet caps at that for just $5 USD delivered. That 618T-3 works very well now after
I did a little tube replacement and alignment.

My very first on the air contact with this one happened to be on 40meters with a fellow ham who serviced them when he was in the US Navy.

Since then I have acquired five more 618T-3s one of which receives OK; but, does not transmit. I suspect an incorrect wiring issue in the tray to control
head line. This is my current project. It has the mobile type control head. I have not yet tried the others.

My goal is to eventually get them all up and running. I have enough control heads, five trays or interconnecting cables, two test harnesses, a 490T and
another Collins tuner for them and the module extender set.
I once again have a pretty complete manual set.

I used the sources that you listed on your 618T page as well as Newark for some of the connectors. Fair Radio was a very good source. But, I
did find three of the trays on ebay. Two of them were only $30 each complete with the 60 pin connector; BUT, shipping from Australia was a
REAL killer!!! Sigh --- as they seem to be made of unobtainium one has to pay the price.
I am very sorry that this is getting so long. But, maybe some of this is of interest to other 618T () users. I am no expert just lucky; but, if any
one has questions, I would be happy to try to help them.
73 de Bob K8RJ



Dear John,
congratulations for your web site, I found many useful Tips when restoring my AN/ARC-102.
Thank you so much and  I'm happy to send some foto's of my 618T-3 .

Hi John,Yesterday, I came across your beautiful WEB page.  As you and others, I have the 618T illness. It isincurable, I have also contracted the MRC-108 illness.  I am pretty sure that the 618T illness is a strain of the 400Hz virus.           Frank, KF5RXV 
Carlo   IK2CNC , has two 618T's fully functional plus lots of other goodies. 

I had three pictures,  and loss them (somewhere) got this picture form QRZ


Lampros SV8FCF had his 618T up and running, home brew  28vdc to 400 cycle converter, 
Lampros also has a jeep, maybe some day he will get all the parts to make a MRC-95 mobile installation ??
Roger F6FER
The 618T-3 is placed on two aluminum angle pieces fixed to a
mounting base plate in the bay.
Low voltage power is supplied by a pair of Lambda 28V-23A PSUs,
one supplies power to the transmitter section of the transceiver, the
other one feeds the receiver section and utilities.
The 110V-400 Hz is supplied from a home made pure sine inverter.
The control box is a 714E-3, and is inserted on a home made 19" mounting
panel with  jacks for Phones, Mike/PTT, Key, Data input and a switch
for the pilot lamps.
The set up is completed by a Collins antenna coupler CU-351/AR 
and a home made VSWR meter.

I was lucky enough to get the rear connector for the transceiver
and the circular connector for the control box, it is not easy
to find parts at a fair price in France. All remaining mounting, wiring
and connections are home brewed.

I have 2 other T3s, one is OK for reception, the other one is out of service.
Food for trouble shooting.

I am not an expert, just a lover of these Collins beasts.

Roger F6FER
Paolo   IW6BET  

Dear John,

I want to thank you for your help and your patience.

My 618T-3 is working well, I used it in several QSO with no problem, excellent frequency stability, good output power.

The only problem that remains to be solved is the fan noise, but I think there is no solution! After all, it is part of the charm of the radio!!

Attached you will find a photo of my setup, I hope you will like it.

Thank you again John, I hope to find you on frequency.

73 de Paolo, iw6bet 

Here is a photo of my Collins airborne station at my newQTH in California.  I have two of the 714U-5M's - one pictured and another in my garage. I still have three 618T-3B's plus I found a second test box that supports 100Hz steps plus another 714E-6 control head just a few months ago in England.73 de Norm - WA3KEY




If you want to send pictures, emails, anything  , just send to k0ip(at)k0ip.com

some of the PDF's on this page came from 
wheres there's MANY US Military manuals.

LOTS of military radio system manuals are at

I hope this page has helped you in some way to make sense of all the parts and
pieces of the 618 radios.   please contact me if your in my part of the world, for
a eyeball QSO at my house,  , see the info at the top of this page



Non 618T  books you can download

Harris RF-550
Book for Harris RF-550    a big file !!!

TBX-8  ww2 military transmitter receiver
Preliminary instruction book  TBX-8   15 march 1945
Book for the TBX vibrator power supply
Schematic for TBX radio

Books for Southern Avionics Company  Low Frequency airport beacons
Model SS-800AVS  Non-Directional RadioBeacon
AND the PC-1000A Antenna Coupler
ndb_beacon_arco\008 PC 1000A Antenna Coupler 310 85 1.pdf 

Disclaimer: all manuals provided for Amateur Radio use only.
Hello all:
its a bit hard to believe this web as been active for over 11 years and has had  lots of ''lookers''  most probably just looked and said,
..   HI HI ,,,   
However, I hope I've helped some of you get your radio working, or at least taken some
of the confusion out of the process.


It's NOT my intention to be "First in a Google search",  or to out do anyone else's web...
I've heard that some folks are mad because this web comes up number one on a search... 
Just to make it clear I have no control over Google...
I wish everyone good luck getting your radio on the air...  John Wilson KIP

IF you haven't, send in some pictures of your radio and yourself for the ""hall of fame"".