I'd be suspicious of the diagnosis of a bad power amplifier if, indeed, you are seeing 70 watts out. The oscillator stage only puts out a few watts at best; the power amplifier transistors kick that up to whatever the designed power level is.
, you should be able to find a good power/swr meter. Make the investment (about $90-100 for a good one, like a Daiwa). The current
model Daiwa which would do you well is the CN-101L...it sells for about $100 here in the States.
A power/swr meter should be standard equipment
for ANY HF installation
, IMHO, just as it is for ham stations. It will tell you at a glance if your transmitter and antenna
system are performing correctly. You insert it close to the transmitter, using a short pigtail of RG-8X coax with a PL-259 connector on each end.
Again, a 125watt PEP class transmitter will show less than 100W on CW transmit. This is normal. But, whistling into the mic, you should see the meter kick up to somewhere near the 125-watt level, PROVIDING that:
1. you have ample size wiring
to the transceiver (AWG6 at least for runs of more than just a few feet); , HF radios should be wired directly to the batteries -- with appropriate fuses --
not thru a panel or sharing connections with other equipment.
2. your connections are clean and tight;
3. your batteries are up; these radios are designed for 13.6-13.8V input, which is considerably more than a storage battery
will have unless a charging
source is connected; their voltage tolerance is +/- 10-15%; and
4. your antenna
system (coax to the tuner, tuner to the antenna, RF ground system) is functioning properly: clean, tight connections everywhere.
Then, and only then, can you properly diagnose what's going on with your radio.
By the way, the difference between 70W and 125W output is less than 3db...barely discernable at the listening end :-)
Good luck and selamat djalan.
Sorry, I won't be around for a few weeks most likely...going sailing!!!