Using a Lamp to get max brightness out of a tx

[bill knox]

When I did my National Service I did 18 months in Aden working on T1509s there were approx. 10-12 maybe even more but I can remember that when we finished servicing one we would connect it up to a bank of tubular bulbs and leave it running for a while giving it a good soak test before it was put on air, it used to contribute to the heat in the transmitter hall quite a lot, there were also SWABs in the hall as well I think they were SWAB8s but not certain, I did not work on those, there were also some other transmitters but as I did not work on those I cannot remember them

[John M0GLN]

Another use for a lamp is in a crystal controlled TX, a low power torch bulb in series with the crystal will give max' brilliance with max' crystal activity, from what I've read bulbs up to 80mA would be used with FT-243 size crystals, I have a crystal oscillator using a 6AG7 with a HC49 crystal in an 'electron coupled oscillator' mode ( don't ask me any questions about that, I'm not quite sure why it works but it does ) and this lights up a 6V 16mA 'grain of wheat bulb' to bright orange when tuned up.

John

[jamesinnewcastl]

Originally Posted by G6Tanuki

One WWII-era military radio I remember had a sprung "tune" button: when pressed it switched the bulb in series with the antenna, put the TX into transmit.

Interesting - that probably explains what the bulb is doing on this aerial current meter used on Stirling Bombers when they used the T1083 (the one before the T1155). I suspect that I would have had 'TUNE' next to the lamp but ergonomics and style were not really high on the agenda back then!

Anyone care to suggest what the three connections were for? (E E1 & KEY COM?)

Cheers
James