[Amps] HARRIS PP-7913/URC POWER SUPPLY

[MU 4CX250B]

This is all good advice. Jeff wants to use a 150mA grid current meter,
so after first isolating the HV return, the grid meter's negative
terminal should be grounded and its positive terminal  tied to  B-,
preferably at the cathode connection in the RF deck. The 0-1A plate
meter should be in series with the B- return to the power supply. In
other words, the positive terminals of both panel meters should be
tied together at the cathode connection.

 There are two other precautions.  One is to protect both panel meters
against an HV flashover to the chassis by connecting  the cathode
(banded end) of a large rectifier diode (e.g., a 6A10) to the negative
lead of the plate meter, and grounding the anode. The second
precaution is to protect the plate meter from an internal tube arc by
shunting across it with a second large diode, with the anode connected
to the positive meter terminal.
73,
Jim w8zr

Sent from my iPad

> On Jan 5, 2017, at 3:42 PM, Doug Ronald <doug at dougronald.com> wrote:
>
> I own two of these power supplies (which I'm trying to sell), and you could
> lift the point E3, the junction of the negative of the filter capacitor with
> the lower end of the choke, place your current sample resistor from E3 to
> ground, then wire the current sample to either C or D on J1, which are
> spares. If you wanted to float the entire negative high voltage supply, then
> wire E3, and E2 in parallel over to J1 pins C, and D. I wouldn't float the
> entire negative supply much above ground unless you mount L1, the 8 H
> swinging choke on standoffs, as it's insulation won't support the full 3300
> volts which is why it's in the negative side in the first place.
>
> Note that E3 also has a ground to the negative of the 13.6 VDC supply, and
> the line neutral. You would want to leave that at ground potential, just
> isolate the high voltage supply.
>
> -Doug
> W6DSR
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Ron Youvan
> Sent: Thursday, January 5, 2017 01:48 PM
> To: amps
> Subject: Re: [Amps] HARRIS PP-7913/URC POWER SUPPLY
>
>   Jeff KD4LYH Pederson via Amps wrote:
>
>>          I noticed that this power supply uses a choke in the B negative
> lead.
>> The B negative is grounded directly to the chassis. Most schematics
>> for GG show the B negative lifted above ground a little for metering
>> purposes. The panel meters I'm using are 0-1 amp full scale and 0-150ma
> full scale.
>> Can't I just bond the PS and RF deck together and strap the the meters to
> ground.
>
>   I don't know this power supply, but generally the choke is part of the
> power supply and needs to stay as it is and the point where it is grounded
> can be lifted and connected through a big (10 Ampere) diode to ground in the
> modern manor.
> --
>   Ron  KA4INM - Youvan's corollary:
>                 Every action results in unwanted side effects.
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