[Milsurplus] Collins automatic antenna coupler / tuner

[David Ross]

Here's a quick rundown on 490T antenna couplers.


490T-1 is the basic antenna coupler, rated at 630 W pep or 200 W 
average, requires 115 Vac 400~ single phase power at 100 W maximum.  
Cooled by natural convection and radiation -  no fan.  Has relay 
circuitry which bypasses the coupler during receive operation -  
receiver connects to BNC connector on front panel.  1 ATR 'short' package.

490T-1A does not have the coupler bypass during receive operation -  no 
relay and no front panel BNC connector.

490T-2 is like the 490T-1 but the -2 has an internal fan.  Rated at 500 
W average and 630 W pep, and the marketing brochure says "4:1 vswr 
antennas, 1200 watts average and pep".  1 ATR 'short' package.

490T-2A is short-circuit proof and open-circuit proof.

490T-3 is a larger coupler rated at 1250 W average and 1600 W pep.  Used 
with higher-powered transmitters like later ARC-58s or the 548L-4A.  No 
internal fan but requires cooling air from the mount.  Power options 
include 115 Vac 400~ or +28 Vdc.  3/4 ATR 'long' package.  Designed for 
'simultaneous operation' -  simop allows for use of the coupler near 
other high-powered RF emitters.

490T-4 - unknown

490T-5 is a pressurized version of the 490T-2.

490T-6 - unknown

490T-7 - unknown

490T-8 is a pressurized & waterproof version of the 490T-3.

490T-9 is a 490T-2 set up as a retrofit for the 180L-3 or 180L-3A.

490T-10 is a 490T-1 in an explosion-proof case.

490T-11 is a 490T-2 set up as a retrofit for the CU-991/AR.



   The 490T-1, -1A, -2, -2A, -5, -9, -10, and -11 all use relay logic to 
sequence their operation, but some later units have solid-state 
controller modules which use 74LS TTL and 4000-series CMOS integrated 
circuits in through-hole packages.
   The 490T-3 and 490T-8 both use integrated circuit controllers with 
early flatpack ICs -  they are difficult to troubleshoot and difficult 
to repair.



   The 490T-1A is a nice piece of Collins clockwork, it tunes quickly 
and makes wonderful noises while doing it.  You have to feed it 115 V 
400~ power while it homes or while it is tuning, but after it tunes it 
is quite happy if you remove the 400~ power.

   Like Francesco says, the ARC-174 has a built-in antenna coupler and 
doesn't require an external one.  The ARC-174 uses the 548S-3, a 
solid-state 100 W PA with an internal high-pass tee-network coupler -  
it is the fastest mechanical antenna coupler I have seen -  just 
zip-zip-zip and it is done.  The ARC-174 is very similar to the 718U-1 
(TRC-169) 100 W manpack.



73
Dave Ross    N7EPI





On 4/11/2011 9:23 AM, Francesco Ledda wrote:
> You are right. My 490T-9 has an ARC-174 tag.
>
> But, this is confusing:
>
> I have an ARC-174 system, and this has a 100W RF amp with built in coupler. What amplifier was used with the 490T-9?
>
> Sent from my iPhone
>