[Amps] SB220 Meter blown

[Jim Thomson]

Date: Fri, 15 May 2020 11:10:06 -0400
From: Artek Manuals <Manuals at ArtekManuals.com>
To: "amps at Contesting.com" <amps at 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.

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