Or my call sign WG2XLP which is just recently authorized for SSB.
A grid driven 3-500Z should be close to what I am looking for. At a low frequency like 70 KHz, I would think neutralization would not be required? How much higher gain would the tube have?
Pat
N4LTA
WG2XCT
WG2XLP
I would use the same short-connection practices and good quality parts as with any RF HF amp. Parasitic oscillations can occur just as easily with a LF amp. Just like when we sometimes need to add parasitic suppressor chokes in the grid and plate leads of audio modulator amps.
You will not need neutralization at <500 Khz for stability, but it will help to make a cleaner amp due to NFB. Considering at 70 kHz a 3KHz ssb signal (4%) is like running 280 KHz wide bandwidth on 40 meters, it will pay to make the amp as clean as possible for your band neighbors.
Grid driven may be best - GG might be difficult cuz how wud you make a bifilar choke that is 500 ohms at 70Khz to carry 14A?
Take a look at the gain vs: freq curves for the tube. I would guess that gain would flatten out and be similar anywhere below 2 MHz or so, but never checked...
Have fun!
T