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[Amps] Caps across rectifier diodes test

To: <amps@contesting.com>
Subject: [Amps] Caps across rectifier diodes test
From: "Carl" <km1h@jeremy.mv.com>
Date: Wed, 4 Mar 2009 20:50:43 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
The tests took a bit longer than planned but I sort of got carried away 
plus had other things to do.

The amps listed below were tested in both standby with just the PS & 
bleeder current, and also keying the relay control line.

Test equipment is a Tek 7704 with an aftermarket 2kV, 100X, 150 mHz 
probe. In order to keep the tests identical I built a string of 
resistors on perf board so I could attach the probe at some point just 
below the probes rating as well as several lower points. Nothing fancy 
and using clip leads to attach the board into the power supplies.

I also substituted a regular 10X 300 mHz probe for the lower voltages 
and looked some more.

Amps tested belong to me or were in for repair or 6M conversion.

LK-500ZC, LK-800C, Alpha 76PA, (2)MLA-2500, DTR-2000L, AL-80A, NCL-2000, 
(2)SB-200, SB-220, HL-2200, Clipperton V.

Rectifiers ranged from the 600PIV Heath, 1N5408's and a couple of diode 
blocks.

At no point and no matter how hard I tried were there any sign of noise 
on the trace that could be construed as diode hash. I retested the 
AL-80A with the factory .01 caps removed and no change.

I next built up a 3 per leg 1N4007 string to replace the 5U4 in a 
vintage HQ-129X on another bench. This uses a 2 stage capacitor input 
filter with 2 chokes. Everything looked fine using a regular probe.

While certainly not a scientific exercise it was the best I could do 
with what was available, and I wasnt sure what I would find, especially 
with a few.  The NCL-2000 is a 1963 engineering prototype that Ive been 
using on 6M since 1964; it still has the original Solitron 5KV stacks..

Any comments welcome.

Carl
KM1H



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