I recently acquired a basket case Collins 30L1 and successfully
replaced the filter capacitor,diode and bleeder board. The result was
a welcomed increase in voltage to about 2Kvdc on the plate. Added an
antenna (12VDC) soft key for solid state exciter compatibility. With
everything checking out OK, I attempted to load up the amp for the
first time. With about 10w of drive on 80m I made 100w output but the
antenna tune capacitor was almost completely unmeshed (minimum
capacitance) and no resonance dip. Plate tune dip OK! With 50w of
drive achieved 400w output with no antenna tune (unmeshed) load
capacitance. Plate tune dip OK. On 40m pretty much the same results
however on this band the antenna tune capacitor was completely meshed
and no dip on this control. Plate tune cap dip OK. Output on 20m was
very low and on that band there was no mesh (minimum capacitance) on
the antenna tune cap. Plate tune dip OK. Didn't go any farther with
the tests. Admittedly, I'm not at all familiar with the
characteristics of the Collins 30L1; consequently, I'm not quite
certain where to begin to look for a solution. The swr between the
exciter and amplifier was within tolerances and the exciter power
output was not folding back. I was wondering if the above set of
facts indicates that one or more than one of the 811A's is in need of
replacement or perhaps the problem is elsewhere. Any comments would be
appreciated. Regards, Ron W2CQM/3
PS: If you're interested in the replacement filter/bleeder PC
board accompanied with brief annotations, visit:
http://briefcase.yahoo.com/W2CQMron and select "Collins 30L1"
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