Date: Thu, 23 Sep 2010 19:58:55 +0800
From: Alek Petkovic <vk6apk@bigpond.com>
Subject: Re: [Amps] Pulse tuning
To: dezrat1242@yahoo.com,amps@contesting.com
Message-ID:
<20100923115856.LAIE8424.nschwotgx01p.mx.bigpond.com@MARMION.bigpond.com>
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At 07:22 PM 23/09/2010, Bill, W6WRT wrote:
>ORIGINAL MESSAGE:
>
>On Thu, 23 Sep 2010 03:57:11 -0500, donroden@hiwaay.net wrote:
>
> >If you have to pulse, you are relying too much on power supply capacitors.
> >Just build it "large" and don't worry about pulsing.
> >Don WA4NPL
>
>REPLY:
>
>I agree. If you HAVE to pulse to avoid damage, you amp is running on the
>edge of self-destruction anyway. Beef it up so it can run full carrier
>for at least five minutes at a time with no sweat. Then you can tune it
>up the 'right' way.
>
>Bill, W6WRT
Surely, with pulse tuning, you are getting the duty cycle as close as
possible to ssb conditions. Therefore you are tuning your amplifier
to the absolute optimum level.
When you tune with full carrier, power supply sag come into play in a
big way and so, once you have tuned your amp under constant carrier
conditions, it will be less than optimum for ssb operation.
Tell me if I'm barking up the wrong tree but I see pulse tuning as
the obvious way to go.
73, Alek.
VK6APK
## Myself, and everyone here in town has used pulse tuning since the
late 70's. Alek is correct. You are better off to use pulse tuning, and
tweak the
duty cycle such that it's the same as the mode you will be using. On some of
these amps, the B+ regulation is crap. Tune with a dead cxr and ur po will be
way
less than when on ssb. On ssb ur average B+ will be a lot higher. Tune with
a cxr,
and you have NOT tuned up for max pep out, when on ssb.
## 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. Why beat
the crap out of the tubes, bandswitch's, plate xfmr, and everything else ? If
somebody doesn't like
the string of 60 wpm dots, then they can either QSY...or turn on the auto
notch. If I'm in a ssb
round table, and have to tweak the amp, I switch to CW.. and use the opposite
sideband...so the
folks in roundatble hear........nothing.
later... Jim VE7RF
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