[Collins] Pre War Collins gear

[Dr. Gerald N. Johnson]

On Tue, 2009-11-10 at 23:51 -0800, John Barnwell wrote:
> I see much discussion regarding "A" and "S" Line gear, but never anything with regards to the Pre War 1930's Collins gear. Are there owners/collectors out there who might actually use this gear from time to time, or is it mostly tucked away in a static display for simply admiring. I have a keen interest in these early Collins transmitters from the 30W to the 45A and would like to hear from anyone who has a similar interest in these early units. Please feel free to contact me directly at radioniner at yahoo.com, thank you. John Barnwell
> 
There is a 10A in the operating hamshack at the Broadcast Museum in the
twin cities. Its an early one and has no provisions for turning off the
oscillator plate voltage for receive without killing all the filaments
too. But then maybe they warmed up fast enough and with it being early
for crystal control, it wasn't likely that answers would be on the same
frequency. A couple years later an oscillator B+ switch was added to the
production transmitters according to that vintage Collins Signal.

There are some other vintage rigs around, but not many because I don't
think they were made by the thousands and lots of working ham gear got
drafted for the beginning of WW2 and never returned or survived. Or went
into scrap metal drives. That plus the fact that they weren't shielded
or filtered for harmonic reduction put many into storage when TV came
along. I'm sure they had a cleaner output spectrum than a rotary spark
transmitter, but probably not any better reduction of harmonics. The BC
museum operates a rotary spark transmitter without an antenna for each
group of visitors. I'm sure the neighbors wonder what that is on their
analog TVs but now wonders why their digital TVs quit.

The A, V, and S line came after TV and still do a good job today as far
as TVI is concerned and have great stability and pretty good receiver
performance. So they are more likely to be used.

One other possible factor is that the 30s vintage transmitters have been
collected and are too prized to change hands often.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer