On Wed, 23 Apr 1997 21:24:22 -0400 (EDT) "Tom Rauch (W8JI)"
<W8JItom@worldnet.att.net> writes:
>Tank losses are minimal anyway in most PA's. Look at the ratty tanks
>Amp
>Supply and Dentron used. They had one coil size for 20 different
>designs, Q was all over the place, the placement of components was
>poor,
>and so on. Yet if you gut one and rework it to the alleged "magic Q"
>of
>twelve with good components, performance changes are small.
>
>In a typical modest sized component tank, the actual loss is only a
>few
>percent. Why spend big bucks and be inconvenienced just to gain back
>one
>or two percent?
Several years ago I built up a bunch of SB-220 amps as mono-banders for a
MM contest station. The difference in performance on 15 and 10M was
astounding.
By ripping out all the input switching and most of the plate circuit,
including the switch, output power went from 900W to 1300W on 10M. Thats
a wee bit more than two percent. No more bandswitch meltdowns or
capacitor arcing either. Plate LC ratios were optimized for the magic
Q=12 and the new input circuits used T80-2 and -6 toroids and ARCO
trimmers.
Prior to the rebuild, amp problems of one sort or another were common
place.
I am certain that just going to an optimum Q played only a small part;
the overall design/layout of the 220 was inefficient IMO.
My "ratty" LK-500ZC runs 1200-1300W on all bands by comparison, has never
arced or blown parasitic suppressors. Pretty decent design and good
components considering its selling price.
73....Carl KM1H
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