[Milsurplus] TCS-9 Output matching?

[WA5CAB at cs.com]

Roger,

The modification you refer to (moving the RF Ammeter from the ground side 
of the Variometer to between the antenna post and the T/R Relay) occurred at 
S/N 9363 of TCS-12 production.  The final NAVSHIPS does not say why it was 
done.  TCS-13, -14 and -15 also have it at the antenna post.

The only official Navy mod for coaxial cable I know of was to use it with 
TN-233/SRC to feed RG-162/U hard line and apparently still feeding a short 
antenna.  The phantom antenna included in the tuner is 12.5 ohms in series 
with either 100 uuf or 300 uuf.  The only change to the transmitter (and 
receiver) was installation of Type N chassis connectors.  Coax used between the 
transmitter and tuner was RG-9/U.

If the phantom antenna you have is the A-58, it has 10 and 5 ohm positions. 
 The 10 ohm position works OK with the TCS and the BC-1306.  And it was 
originally made for the BC-191 in SCR-193.

In my experience, the basic TCS transmitter will load a 30-50 foot end-fed 
wire satisfactorily.  That and a standard 35 foot whip are what I've seen 
used aboard several vessels.  And a 40 foot wire is what my TCS-14 is hooked 
to.  If I were to need to feed a coaxial cable fed antenna like a doublet, I 
think I would opt for the 1:4 balun (technically I guess it would be an 
unun) at least in part because it is smaller and would be one less control to 
fiddle with.

In a message dated 5/5/2011 2:13:12 PM Central Daylight Time, 
Roger at new-gate.co.uk writes: 
> I think the mod I heard about was a link winding over one of the coils 
> in the output circuit, so quite like the balun suggested by another 
> poster. Using a Windom is a possibility here too, so I may give that a 
> try. I'd be interested to know what the military did when they wanted to 
> use the TCS with a bigger antenna than the supposedly standard 20ft whip.
> 
> The mod to move the RF ammeter to the antenna lead was apparently 
> because under certain (unspecified) circumstances the meter in the 
> ground lead could show a reading when the in fact little power was going 
> out to the antenna. I have a second, junker, TCS TX here and that has 
> either had the mod done or was built that way.
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480