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 -- KØIP
Something new, the 618T-2 page A work in progress.
and the ARC-105 page, some good info
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.
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 (a) ida.net call 208 251 6441
FYI: There's a Collins 618T User Group
|Fellow Hams, especially DX visitors to the USA,
BE MY GUEST
|Note, way at the bottom of this page, there are a
few other radio PDF's !
||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 (a) in an email address,
you need to change it to a @. and close any spaces, emails have NO spaces.
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
Those S-Line jockeys don't like aircraft audio HI
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.
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. 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 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 had 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:
426T1 400Hz power supply
400 hz POWER SUPPLY INFO
For more info about the power
Collins 426T-1 400 cycle power supply, this supply is used in the MRC-95
This is rated at 115Vac Square wave, 400Hz, 630VA
click here for Schematic
bigger view, Front Back
EKCO STATIC INVERTER-E182 Click for Schematic
Another Collins inverter, made for
also a T-195 Dynamotor
will probable work if its all you can find, as might
|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
24 VDC supply
One possible recommendation: shop Ebay for a Lambda
|Control Head, be sure to read "618T sales".
learn a lot about the correct parts and pieces.
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
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.. 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?
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
|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|
Looks like Amphenol 4 S81 ??
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
This is the 49-T4 Retro fit rack .
Note: the WIDE sides..
the non-retro mount, I think is
TEST SET's Proper name "" Test Harness, Radio set AN/URM157""
|Please NOTE: These are great to have, There are several different configurations, the older units, like the one on the left has a toggle switch to select the type of control head, does not work with the 3B model radios, it works except for the 100 Hz switch doesn't connect through to the radio. The unit on the right has a rotary switch and does include the connections for the 3B radio (see just below).. if you get the entire test set, it comes with many cables, to connect all the 618t parts and pieces together. if you can get the complete TEST HARNESS it's everything you need , other than the Power Supplie(s) to get on the air .|
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 .
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..
click me to make me
||heres some pictures
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
(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
The "wire" designations are not the same as the PINS on the control head connector !!
here is 3 different views of the same thing
|Other Webs with 618T information|
|* look down this link for the "618 overview"
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 ,, LINK
Here is a list of non-618t webs about things I find interesting !
* Heres a web with info about TACAN, IFF transponders, and other vintage avionics http://members.home.nl/a.k.bouwknegt/index.htm
* 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
More pictures and information about a restored jeep at Wright Patterson National Museum USAF.
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 mostly useless
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
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,
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
From N6CC more pictures coming,
More info link N6CC
|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.
more info LINK N6CC
Radar, sonar, sonobuoy receiver/ recorder system, VHF R/t x2, and 2 each 618T-3 with 490T-1 in a "hut".
|More navy info, from
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
|SH-3 Sea King ARC-102/RT-618T3
EA-6B Prowler ARC-105/RT-618T1
P-3 Orion ARC-94/RT-618T2
|Possible First product review ??
Collins Signal Magazine 1960.
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
Operational 618T's Hall of Fame !! send me your pictures and letters One left click on most pictures enlarges them !
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 appliance operators, worried about their D104 mike audio...
check into their 20 meter Sunday net with your airline quality audio..
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
|some comments from Leighton GW3FSP:::::
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
, has two 618T's fully
functional plus lots of other goodies.
|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 ??
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,
this map installed 1 Jan 2013
once upon a time I had a survey posted here, and may of you responded. and I enjoyed all the great comments
however most of the time I would forget to check it for weeks at a time, SO, I removed it.
If you want to send pictures, emails, anything , just send to wa0dyu((AT))gmail.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 the page
HELP us get one of these working ,
looking for anyone that owns or has a working TSC-60 radio shelter..
not the one with HF-80 radios but the earlier version.
here are a few pictures. click picture to enlarge.
check this link for more pictures,
if you know anything about this radio where to buy one, anything please email me k0ip (A) ida.net
to donate see this link