Date: Thu, 23 Sep 2010 16:45:28 -0700
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
Subject: Re: [Amps] Pulse tuning
On Fri, 24 Sep 2010 06:23:51 +0800, Alek Petkovic <vk6apk@bigpond.com>
wrote:
>
>That's exactly my point. You keep presenting my argument for me.
>
>By tuning up at 100% duty, your are not tuning to 100% output because
>your voltage has sagged.
>
>With pulse tuning at 30% for example, you eliminate that voltage sag
>problem and you are tuning much closer to that ideal 100%.
REPLY:
No, you are missing my point. By tuning up at 100% and getting some
voltage sag, when you go to a lower duty cycle like SSB you have less
sag and more headroom. Thus less likely to splatter, and equal or
slightly more power output.
Bill, W6WRT
## say what ? Not a chance. Tune up with say 1200-1500w out
CXR, VS pulse tuning with a 20-30% duty..and watch the diff on
the pep wattmeter.
## if you pulse tune to 1.5 kw pep out, then switch to SSB, you will be dead on.
If you tune to 1.5 kw, with a CXR, then switch to ssb, B+ is no longer
sagging..and
PO is up a bit. Amp was never tuned up for the higher power,cuz of the lower
duty
cycle. IF you had gone back and pulse tuned it, you would have seen the po
increase
to 1600-1700w pep. With the amp pulse tuned to 1600-1700w pep out, and
drive
reduced, so amp is putting out only 1.5 kw pep, now you do have some heardroom.
## if u insist on tuning with a cxr, at least, when done, overcouple the
loading a bit, till
the po drops 2% [30w]. Now you have effectively got the loading where it
should be.
Jim VE7RF
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