[Amps] Last question on Amp Supply LK-500 no tune

[Jim Thomson]

Date: Sun, 18 Feb 2018 09:19:58 -0500
From: Ham H <kghams at gmail.com>
To: amps at contesting.com
Subject: [Amps] Last question on Amp Supply LK-500 no tune

<I now have the amp working perfectly with one exception. 160 meters has no
<output. When I looked at the schematic they had a fixed loading capacitor
<for 160 that says it was factory selected.

<Well the pin on the bandswitch where that cap would go has no connection.
<All bandswitch wiring is origianal and still has green paint on all
<connections and the pin where this cap should go has never had solder.
<Looks like it was never installed in the factory.

<Does anyone have any idea what ball park value that cap is?  I know other
<bands have air var caps that go to 500 pF .

<Thanks

<Gary K4MT

## The no tune versions of their amps are interesting.   They are all pre-tuned in the middle
of each phone band.   So what happens when you want to qsy within a band ??   I dont see
any  tune + load controls on the front panel of the box.  It appears you have to  keep taking the lid
off, and retweaking the  small variable cap for both the tune and the load, for each band..pita. 

##  IE:  they depict a fixed cap + small varaiable  for both the  tune and load..for each band. 
The bandswitch just changes taps on the coil, and also switches the required  caps for each band. 

##  so sure, its no tune, sort of.  But its only going to be tuned for one freq..on each band.   I can tune
my L4B at 14.200  and its good from  14.100   to  14.300  without retuning.   On the lower bands, it requires
a  lot more tweaking.   On 80  + 160  I can see this being a real pita. 

##  The no tune  LK-500 is a 3 x  3-500Z... complete with an outboard 60 lb dahl xfmr.   Thats a big mother of a
xfmr for any linear.  Still its only 3250 vdc  no load on RX.   I can see perhaps aprx 2300 watts pep out, assuming
3 kv under load of  1.2 A       400 ma per tube. 

Jim   VE7RF

Jim  VE7RF