[Milsurplus] Collins automatic antenna coupler / tuner

[David Ross]

On 4/11/2011 6:06 PM, Mike Morrow wrote:
> David Ross wrote:
>
>> Here's a quick rundown on 490T antenna couplers...
> Excellent info!  I was hoping someone would jump in with real
> information.  It's going in my archive.
>
> You wouldn't have similar info about the different versions
> of the 618T, would you?  I've lost track after 618T-3.
>
> Mike / KK5F
>




   Yes, here it is.

618T-1 is an HF transceiver covering 2000 - 29999 kHz in 1 kHz steps.  
It is rated at 400 W pep and 125 W carrier on AM & CW.  It is in a 1 ATR 
non-pressurized case.  There is a 618T-1B model that is synthesized in 
100 Hz steps.  Power requirements are 28 Vdc at high current and also 
115 Vac 400 at 165 W  The 400~ power runs the two-speed fan and also the 
PA tuning servomotor.
   The 618T-1 is a retrofit for the 618S and a rack adapter is available 
to put the 618T-1 in the older 618S rack.  A second part of the retrofit 
is the 516H-1 inverter, which fits in the mount for the old 618S 
dynamotor.  The 516H-1 requires 28Vdc and creates a weird voltage at a 
weird frequency -  I forget the actual numbers but it is something like 
600 Vac at 1200 Hz -  this powers the high voltage supply inside the 
618T-1.  Collins intended the whole 618T-1 & 516H-1 package as a simple 
retrofit and it was just that -  splitting up the power supply in this 
way, with part inside the 618T package and part in the 516H-1 package, 
allowed the retrofit to go into the old airframe without any mods to 
structure or wiring, a big plus.

618T-2 is pretty much the same radio as the 618T-1 but requires large 
amounts of 400~ 3 phase power.  The 400~ single phase power requirement 
is still there, for the fan & servomotor.  The -2 radio also requires 
+28 Vdc at 120 W.  Other specs are identical to the 618T-1, and there is 
a 618T-2B that operates in 100 Hz steps.

618T-3 is the common one, requiring 28 Vdc at 1150 Watts and 115 Vac 
400~ at 100 Watts.  Other specs are the same and there is a 618T-3B 
model that does 100 Hz steps.

618T-4 - unknown, probably the same package but with different power 
requirements.

618T-5 - unknown, ditto.

(Several control heads exist for the 618T radios, the 714E-2, 714E-3, 
714E-3B, 714E-3D all work with the 1 kHz step radios and the 714E-6 & 
714E-6B work with the 100 Hz step "B" models.  The 390J-1 shockmount 
will work with any of the 618T radios.)

ARC-102 is the military nomenclature for a package containing a 618T-3 
radio, a 714E-2 control head, and a 390J-2 shockmount with a 488A-2 
inverter.

ARC-105 is a pressurized version of the 618T-2.  The ARC-105 has it's 
own control head and antenna coupler and antenna capacitor and antenna 
coupler controller.  The marketing brochure says "Designed to meet 
high-performance military aircraft weapons system requirements" and "for 
operation up to 75,000 ft." but isn't specific about what plane or 
planes the ARC-105  was used in.

ARC-112 is another pressurized version of the 618T-2.  The ARC-112 has a 
separate receiver/exciter package and power amplifier package -  
probably done to allow the radio set to squeeze into smaller spaces in 
the airframe.  There is also an antenna coupler and a 'vacuum dielectric 
variable capacitor' and an antenna coupler controller for the ARC-112.  
Again, the marketing brochure is not specific as to application, but 
mentions a 50,000 ft. altitude limit.  (I have never seen any ARC-112 
parts, but I think that they may be a missing link, a throwback to the 
ARC-80 radio which was an amalgamation of ARC-58 family pieces and 618T 
family pieces.)

HF-105, -106, -107, -108, -109, -111 systems seem to have been designed 
with marine use in mind.  They come in watertight cases and appear to 
use the same 490B-1 antenna coupler that shows up in both the MRC-95 & 
MRC-108.  The main differences appear to be in power requirements:
HF-105 - 27.5 Vdc
HF-106 - 120 Vac 60~ single phase
HF-107 - 220 or 440 Vac 60~ three phase
HF-108 - 208 Vac 400~ three phase four wire
HF-109 - 120, 220, or 440 Vac 400~ three phase
HF-111 - 220 Vac 50~ single phase
The photo shows a large rotary inverter, probably used with any of the 
50~ or 60~ systems.

MRC-108 is a 618T-3 packaged in a watertight case and carried in the 
rear of an M151 jeep, along with a VHF FM radio, a VHF AM (aircraft 
band) radio, and a UHF AM radio and appropriate antennas.  All the 
radios are on an aluminum pallet that is tied down behind the seats in 
the jeep.


   That's all that is shown in this brochure, titled  "618T-( ) HF 
Transceivers", it is dated 5-73.    By the way the 490T antenna coupler 
information was from another brochure titled "HF Antenna Couplers", also 
dated 5-73.


73
Dave Ross    N7EPI