[Amps] Tuned inputs for any GG HF amp.

[Jim Thomson]

donroden at hiwaay.net donroden at hiwaay.net 
Wed Feb 17 18:19:16 PST 2010 

  a.. Previous message: [Amps] GS-35B Input 

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I think large variations in drive impedence through the rf cycle are  
somewhat smoothed out by a low to medium Q input..   BTW, L-C-L (  
lowpass ) might be better.

Don WA4NPL

 Broad band does not work.  The Henry 8 k used one.. and lousy input swr. Henry also said, DON'T use the auto tuner in ur xcvr. Just put up with the lousy swr.  No fly wheel effect.   Instead of 9 x  bandswitched  pi nets,  I use  2 x broadcast variables + tappedcoil. Caps padded on 160m.  FLAT  SWR  across all bands. Besttuned input I have used by far.  just use small straps, for taps,which will minimize stray C.  A 2 x wafer switch used.  Wafer 1changes taps.  wafer #2 pad's C2  on 160m only.  Entire coilused on 160m, so 160m pos of wafer #1, used to pad C1on 160M.  I used 6;1 verniers.  very FAST band change..just dial by the numbers.   I put wattmeters on both sides+ dummy load.  I was losing a bit too much power on 17 + 15 m taps. [ 220 w in- 160 w out]  So increased uh by a 1/4 turn, then presto, output wattmeter is way up.  Later... Jim   VE7RF  
Quoting "MIKE DURKIN" <patriot121 at msn.com>:

>
> Just a thought/wondering .. why is it that a broad-band 1:1 torroid  
> un-unun not used for the input of a single GS-35b instead of several  
> C.L.C. networks ?? Is there not enough fly-wheel effect to keep a  
> good linearity??
>
>
>
> Mike