That agrees with what I posted yesterday.
Carl
KM1H
----- Original Message -----
From: "Gary Schafer" <garyschafer@comcast.net>
To: "'Carl'" <km1h@jeremy.mv.com>; <amps@contesting.com>
Sent: Wednesday, March 04, 2009 8:59 PM
Subject: RE: [Amps] Caps across rectifier diodes test
> The only time that I have seen hash from diodes was in a power supply
> that I
> built to power a BC453 receiver with a converter ahead of it. The
> power
> transformer I used had too high a voltage so I used a choke input
> filter
> behind the diodes. The power supply made lots of noise up close. I
> cured it
> by placing a .01 cap as the input filter capacitor. No more diode
> noise.
>
> 73
> Gary K4FMX
>
>> -----Original Message-----
>> From: amps-bounces@contesting.com
>> [mailto:amps-bounces@contesting.com] On
>> Behalf Of Carl
>> Sent: Wednesday, March 04, 2009 8:51 PM
>> To: amps@contesting.com
>> Subject: [Amps] Caps across rectifier diodes test
>>
>> 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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>
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