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The easiest way I found to measure power supply
current is to use a calibrated shunt, that produces a known voltage level at a
specific current. I found a brand new one at Nebraska Surplus Sales for
around $12, and it produces something like 100 mv. at 20 or 25 amps. A
digital voltmeter across the shunt gives you a pretty accurate
reading. I was able to find high wattage resistors of the right
value on eBay, for a heck of a lot less than the price of four headlamps.
73, K8AC
----- Original Message -----
Sent: Sunday, March 19, 2006 11:31
AM
Subject: Fwd: Re: [drakelist] Follow up
to PS7 Regulation Problem
Kevin -
There are a number
of options available to you, but in all cases you will need an Amp meter in
series the output of the PS7.
1. Obtain some automobile
headlamps and use them as loads by placing them in series. Probably
about 4 will do to produce the 3Ø Amp load.
2. Key down in CW on 2Øm
into a dummy load. Adust the output of the TR-7 to draw about 25 to 3Ø
Amps...Remember to have the Amp. meter in series with the output of the
PS7.
3. Nichrome wire might be used but be prepared for very hot
piece of wire. Go to: http://wiretron.com/ and calculate the AWG and
length of Nichrome you'll need for a load. This is not the best
method, but will work.
4. You might try using "Flood Lamps" for a
load.
5. Use your
imagination!
73,
Jay/AF2C
At 07:49 PM 3/18/06
-0800, you wrote:
Kevin LaHaie
<[EMAIL PROTECTED]> made an utterance to the drakelist
gang
----------------------------------------------------------------------
Hello
List, and thanks to all the suggestions on the PS7 supply that was
shutting down around 4v.
The supply is working, and truthfully I am
not certain what I did to make it work. I did examine the pass
transistors, 3 of which had been replaced, and I think an emitter might
have been shorted to the case on the way through the heatsink, or perhaps
there was a short to the collector through the mica
insualtor.
Anyway, it is now working, I have set the adjustment to
13.5v, and with full output on the TR7 in CW mode, a solid, steady
voltage. Nice 40 minute QSO on 40 meters and report of great signal
and fine audio was reported. Yeah!
Now, my final
question!
What is the best way to set the regulation board to trip
at 31 to 32 amps? I know there are lots of ways to load up the amp
with calculated load resistance to make it draw 32 amps, but I hardly
think that is the 'official' way.
any help to a tip / trick to make
sure the supply will trip shortly after delivering 30 amps?
Thanks
in advance!
73 Kevin K7ZS
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