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Superstar 3900 and IRF520 dual finals query

Damo666

Member
Jan 10, 2009
50
0
16
Hi Guys. Just bought a Superstar 3900(Cobra 148 rip off) and noticed they've done away with the old 2sc1969 final and replaced it with 2 x Irf520 outputs. Anyway, to cut a long story short, i keyed on fm/am and my power meter shows 10 watts which is fine, however when i talked into the mic on ssb i was only peaking 2 - 4 watts which wasn't good. The only way i could achieve 20 watts or so was to whistle loudly into the astatic mic(i tried several mics to same effect). Even talking loudly didn't achieve more than 4 watt pep. On this note, i decided to open the radio and alter Vr12(ssb power/alc) so that i could voice peak upto about 12 watts or so. It still peaks 20watt or so on a whistle. Having done this, do i need to alter/tune anything else or will me altering this variable resistor have upset any workings of the radio - ie bias, etc. Your comments are much appreciated. Regards. Damian.
 
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i think u will be fine . i would remove tr32 myself but thats me. i would also put the radio on ssb abd adjust the bias to the driver and final for max ssb power
 

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