Comments below
On 5/15/2020 12:13 PM, Jim Thomson wrote:
Date: Fri, 15 May 2020 11:10:06 -0400
From: Artek Manuals <Manuals@ArtekManuals.com>
To: "amps@Contesting.com" <amps@contesting.com>
Subject: [Amps] SB220 Meter blown
<I am resurrecting a SB220 that had an apparent classic Grid/plate short
<event. One of casualties appears to be the right hand meter movement.
<This is the one for Grid Current and HV. I am pretty far into it and the
<meter movement measures open , the internal shunt resistor is blackened
<( and open?)
<Anyone got a surplus movement from a parted out unit? Nothing found on
<evil-bay at the moment
<Dave NR1DX
## I believe harbach sells replacements. The heathkit shop might sell em.
They only have "meter diode/ resistor boards" no actual meter movements
The rest below are all good ideas but moot if I cant find a meter
movement, Nothing in my manual says what the actual values of the
movement is either 8^(
Next time be sure to install rvs connected 6A10s or 1N5408s between
B- of hv power supply caps..... and chassis. HV fuse, followed by 50
ohm glitch resistor is series
with B+.
## Toss all the grid chokes and caps. Bond each of the 3 x grid pins
directly to chassis
with strap.
## Install a 2nd HV fuse...in series with one leg of the plate xfmr
secondary....either leg.
## Ok, now there is no way to blow anything up..including meters. Cro
bar anything u want,nothing happens
except for a blown hv fuse.
Jim VE7RF
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
--
Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|