[Milsurplus] Milsurplus Digest, Vol 85, Issue 10

[Roger Basford]

On 07/05/2011 22:09, milsurplus-request at mailman.qth.net wrote:
> ----------------------------------------------------------------------
> Message: 1
> Date: Sat, 7 May 2011 20:36:40 +0200
> From: "Henry Mei'l's"<meils at get2net.dk>
> Subject: [Milsurplus] TCS PA cathode keying&  ant matching Re:
> 	Milsurplus	Digest, Vol 85, Issue 9
> To:<milsurplus at mailman.qth.net>
> Message-ID:<ECF854D487264404A9CC0A98BB9646E7 at ejerf59be5593b>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> 	reply-type=original
>
> To minimimize/eliminate chirp, I and many others I know key the 1625
> cathodes w/the oscillator and buffer/multiplier stages running. This will
> usually result in a backwave (reduced-level key-up signal), and will not
> allow QSK unless the osc./buffer are sequence keyed some m. seconds prior to
> the keyed cathodes, via the keying relay. Grid block (sequenced) keying
> might be a better solution.
>
Hi Henry,

Thanks for the follow-ups on the TCS matching issue, certainly all the 
feedback has given me plenty to experiment with. Sorry to see that my 
enquiry has set off a bit of a turf war over modifying vintage gear!

After I played around with an external 2 gang variable cap I was able to 
get a good amount, > 1amp RF, into the 66ft "L" I'm using temporarily 
(while I negotiate with my neighbour to allow a longer wire to cross his 
field!).  I have had a couple of 5 MHz QSOs with a CW station down in 
the south of England and an amateur over in Cardiff in South Wales, has 
very kindly sent me a wav file of part of the first QSO I had using the 
TCS. The chirp is quite acceptable to me, with a decent filter at the 
Welsh end it cleaned up quite well and is certainly no worse then my 
1980s vintage PRC-320. Due to the narrow channel restrictions on 5 MHz, 
I kept a close eye on the frequency counter but saw very little drift. I 
did note that in "MO test" there's enough RF in the shack to trip the 
counter, without keying the radio. Has anyone had experience with using 
relatively modern, say HC6/U, crystals in the TCS? I do have a large 
amount of rocks collected over the years and have found at least one 
that will double to 5400kc , another of our 5 MHz channels.

What did come over on the wav file was how easy it is to "clip" 
characters when sending, just a little too fast and it sounds very 
ragged. Knowing that Naval ops generally were renowned for their speed 
and good sending I imagine that it would have taken a concious effort to 
slow down when using the TCS on the key. My error rate at my normal 
speed is certainly poor in the recording, I blame all the racket from 
those relays!

Anyway, hearing the TCS brought back a few memories for us hams who 
where brought up on military surplus over here. When I was first 
licensed in '66 the TCS was very common, as the UK forces had used them 
post-WWII as reserve stations on RN and merchant ships -  but in 2011 a 
good unmodified transmitter will fetch a good price especially if, like 
my station, it's made by Collins.

73 all, thanks for the help,

Roger Basford/G3VKM - Norfolk, England.