BJ300 Chinese HF amp and Hermes Lite

[Malcha Schwatrz]

Has anyone out there used this inexpensive hf amp with Hermes and if so, how much power did it produce and any problems with it?  Thanks

[Heath Petty]

I'm almost certain that this amp does not have the right lowpass filters installed. That means that harmonics would probably be above the allowed limits,  and would not be good for HF amateur radio. You could add an LPF bank, there are several that are on ebay.

-Heath

[Jürgen Weißmann (7ii)]

[Abuck289]

If that's the actual schematic, it has no low-pass filter at all! It also doesn't have any bias voltage; the bases of the transistors are at 0V potential so it isn't running Class AB, it's running class B. Could be OK for FM or CW but not for a linear mode.

Maybe that's not the complete schematic.

Jim WA2EUJ

[Ed Grafton]

That circuit is almost the same as a 2 transistor Texas Star amp (Less receive amp). In otherwords, Class C. CB amplifier. I would not use it on ham bands, exxcept for above mentioned continuous carrier modes. There are no LPFs as mentioned above. 

If you are crafty, you can pillage an old HF radio for the PA & LPF boards.

Ed