Date: Sat, 21 Apr 2012 14:10:19 -0700
From: Scott Townley <nx7u@nx7u.net>
Subject: [Amps] Dynamic regulation in PS
Re: the discussion on choke-input power supply filtering.
What is considered the target value for PS dynamic regulation for SSB?
--
Scott Townley
http://www.nx7u.net
## 1st, your REAL no load B+ is what you have when you hit the PTT, and
No drive is applied... IE: just drawing idle current. That idle current
alone will
drop it down a bunch, depending on plate xfmr used, etc. You have to idle 1st,
before you can even apply drive.
## after that, you don’t want to see it drop at all, or very little on an
average reading
typ HV meter. If its XXX volts when sucking idle current, and no drive
applied, and then
when you talk on ssb, it drops 10 %... IE: now 90% of the voltage on idle,
Id say its
not very good. You need big wire from main panel to the amp to minimize the v
drop
in the 240 vac line alone. Its one big loop, so if you have say 30 ft of wire
to the main panel,
that’s a 60 foot loop. Since I have several amps and load sof other stuff
that needs power,
I opted to just install a 100 A sub panel on the other side of the wall of the
hamshack. Then real
short runs of 10 ga wire to each of the table top amps. 3 ga wire is used
from 100A sub panel,
back to the main 200A panel.
## 12 ga wire is way too small for most purposes, esp with typ lengths
required to get from the
shack to the main 200A panel. 6-8-10 ga will work a lot better. You can
also just install a small,say
60-70 A sub pnale in the shack, or close to it, then feed it with 6 ga wire.
Then short runs of 10-12 ga
to run all the ham gear and 10 ga for the amp. Most ham shacks will only come
with the usual 1-2 x
duplex 120 vac outlets, which will typ be shared with lights and other
stuff...all on one 15A breaker, fed with the
usual 12 ga wire.
## with scopes, several xcvrs, extra power supplies, at least on hf amp,
clocks , misc ham gear, 12 vdc supplies,
lights, 1000-1500 watt electric base board space heater, etc, etc, you may as
well do it right.
Instead of a separate line for the amp, you may as well just install a bigger
line into the shack, and use it to
feed a sub box...then distribute from there. I use those bigger outlets you
see, that are in the slightly
bigger metal box. They contain 2 x pairs of duplex outlets. 4 x 120 vac
outlets in total. I installed aprx
3-4 of those boxes on the back end of my desk. Then one 15A breaker per quad
outlet. Then u have
enough juice to run anything you want.
## If after all that, your dynamic regulation on ssb is still lousy, its time
for a bigger filter cap, and or a
bigger plate xfmr. Other than dropping a tiny bit when on idle, mine doesn’t
move more than a needle width on
ssb, when drive applied, talking on ssb, with loads of processing. If buying
a new or used plate xfmr, size it
a little bigger. It pays off asap. Runs way cooler, and dynamic regulation
is much improved. For your
typ 1.5 kw pep out ssb amp, you want at least a 46 lb xfmr in there.
later... Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|