[Boatanchors] 1930's era cw transmitter

[Brian Clarke]

Hello folks,

Push-pull RF PA for AM at HF is most unusual. Most designs, including Dr 
Drake's ARC-5 and its clones, Collins, General Dynamics and Harris put RF 
tubes in the PA in parallel.

Why? In push pull, each tube is working half the time - so you won't get 100 
W input, let alone output. In parallel, both tubes are working all the time. 
And the killer? Neutralising push-pull is a bear - so much easier in 
parallel designs.

The RCA Transmitting tube manual lists 60 W maximum input for CW as ICAS 
operation for the 807 - less for CCS and for telephony. But if you are in 
the land of plenty and you can afford the time to keep neutralising the 
tubes you melt, go right ahead.

73 de Brian, VK2GCE.

On Sunday, June 02, 2013 9:55 AM, Roger said:
>
> Dave,
>
> The Knight T-50(kit). The T-50 was CW only, 80-10 meter kit. A 6AG7 
> driving
>  an 807 final @ 50 watts input. It is a good design that has
> stood the test of time.
>
> A popular early design done as a 1950's kit out of Chicago.
>
> The 807 will do 50 /60 watts CW. It is a beam power tube.
>
> I could see you running four tubes One as an AM modulated stage.
> A second as a phase shift driver. With a push pull final pair getting you 
> a
> nice 100 watt AM signal.
>
<snip>
>
> Roger AI4NI