Dear collegues
Recently I was lucky enough to buy two KL300
(http://www.rmitaly.com/scheda.asp?IDGr=1&cat=0&tipo=94) amplifier at a flea
market for a reasonable prize (2USD each) and I got them to work again. I
have checked the devices with my FT817 and they work rather well (I know, it
does not have any output filters but I only wanted it for my FT817 to give
it a punch, out there in the "wilderness" when carrying the appropiate
battery).
These devices are claimed to be useful for the whole HF band but I have
noticed a quite non uniform output power over the HF bands. I think the
reason is because my rig folds back its ouput power by noticing an unmatched
input impedance (the antenna is tuned or even a dummy load). Therefore I
have the feeling that this amplifier does not have a flat input impedance
(50 ohm). How can I flatten this impedance or what is done ususally to solve
this problems. I suppose that the input impedance is the input impedance of
the transistors (class B push-pull) plus the resistance put between the
transistor's base and emitter (10ohm here).
I would appreciate your suggestions and solutions. On the above web is not
only the amp itself but also its very simple diagram.
Thanks for your help.
Kind regards,
Stefan
EA5FY
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