If the movement is open on yours you can use a movement from a heath kit
wattmeter. They are the same size meter but the movement has a different
sensitivity. You will need to adjust the shunt/series resistors accordingly
in the amp to make it work. there some articles on the net about doing this.
Somewhere I have the articles if you get stuck, let me know and I will see
if I can find them.
73
Gary K4FMX
> -----Original Message-----
> From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of
> Artek Manuals
> Sent: Friday, May 15, 2020 12:46 PM
> To: amps@contesting.com
> Subject: Re: [Amps] SB220 Meter blown...follow up hope
>
> With nothing else to loose IT removed the meter and found
> that ther are TWO resistors inside. One is in parallel with
> the meter movement and the other is in series. Those both
> have been "toasted" a bit it seems like the parallel one is
> about 15k and the series one is about 1.8k. The 1.8k is open.
>
> Can anyone verify these values they dont appear on the BOM
> since they are internal to the meter itself
>
> Obviously replacing these two resistors is going to be a lot
> easier than finding a replacement meter movement
>
> Hellllpppppp!!!
>
> Dave
> NR1DX
>
> On 5/15/2020 1:14 PM, Artek Manuals wrote:
> > 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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|