Re: Drake L7 Power output
|
From what I have read the plate circuit will be slightly more efficient if you use the CW position if you only want to run around 500 or so watts instead of the full power.??
It is true that when the FCC went by input power the legal way was to tune up in the CW position to 1 kw input and then switch to SSB position if you wanted to run the amp to the 2 kw pep level.? Not needed now as the limit is 1500 watts output.
I use an external switch with a current limit resistor and relay for a 'soft start' and leave the amp switch on all the time.
?A while back there were several people putting out a rebuild kit for the power switch and I bought one but have not needed it.
Ralph ku4pt
On Tuesday, March 5, 2024 at 10:01:46 AM EST, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.
Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
_,_
|
