[Amps] Pulse tuning

[Jim Thomson]

Date: Thu, 23 Sep 2010 22:18:01 +0200
From: "DF3KV" <df3kv at t-online.de>
Subject: Re: [Amps] Pulse tuning


No.
Plate current will not be way higher and dissipation will not either.
I tune for maximum out in the center of the band and don?t touch anything
while moving around in a contest.
Output power drop is not more then 1db at the edges.

Your loaded Q might be too high!

73
Peter

##  u misunderstood me.   Your typ newbie ham, and old timer alike, when
INITIALLY tuning the amp on a new band, will be tweaking the tune control,
looking for a peak on the  wattmeter, and  in the meantime,  will also have 
the tune control on either side of resonance...with typ wild excursions.  That can
easily happen on any amp with No verniers .  Have you ever watched some of these
guys  tune up a linear ?   It's a real hoot.   They start out barefoot, with 200 w out,
then  decide they need... 'more power.'   They flip the amp on, start tuning [typ with the
load control way too meshed]..with 200 w of drive... then after 10 x secs with everything off
resonance, it dawns on them that their amp only requires  105 w of drive !   They  drop the drive
down to 75 w, then start again [ without letting up on the mox]  now it's way outa tune, so they start
all over again.  Then the po is too low and it dawns on em to  crank the drive back up to 105 w.   They
overshoot the drive level, and xcvr is putting out 140 w. 

## after abt 10 x mins of this rigmarole, they finally get it right.   GM3SEK posted a story abt this
old geezer who kept blowing up tubes in his amp.  They got the old guy to tune it for them.  Old guy
had the amp a mile off resonance, then [while amp still keyed, and tubes bright red]..decides to light
up his pipe !  After screwing around getting his pipe finally lit, .." now where were we, yes, tuning up
this amp"    I fell on the floor laughing when I heard the story, but it's true.   I have seen seen similar myself.
A lot of folks don't seem to grasp the concept of applying a LITTLE bit of drive..1st, then resonate the tune cap.
I knew one old guy who had a Swan 700CX..and was trying to use it to drive... a SB-200 !   He had enough drive
for  5 x of em.   He went through 5 pairs of tubes,and decided the amp was 'no good'.

##  95%  of these folks don't have  a real wattmeter, between xcvr and input of amp, and have no clue
what amount of RF they have  going into the amp.  90%  of em don't  use a footswitch either.  

## this why they 'invented'   pulse tuning and pep wattmeters.  Now all you hear is the same folks 
sending 60 wpm dots  for 5-10 mins at a time !   They don't blow stuff up anymore.. and I don't have to fix it. 

Jim  VE7RF






-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On 

##  tune with a cxr, and if something is off resonance a bit, then plate
current is way higher than normal, and po is way less than normal.   Plate
diss is way higher than normal.