On May 29, 2006, at 3:18 AM, Ian White GM3SEK wrote:
> Jeff Strailey wrote:
>> My problem with operating an LK500 following the change to 120 Vac
>> operation appears to be related to a step start mod that was added at
>> some time to the amplifier. Perhaps someone has a schematic or other
>> information regarding a step start mod kit that was sold at some time
>> for the LK500. It is tempting to simply remove it and restore the AC
>> input side of the amplifier to it's original state but step start is
>> desirable if it can be made to work.
>
> It looks like your low B+ problem is because the step start relay
> is not
> pulling in. This means that the resistor is permanently in series with
> the mains... and will be having a very hard time.
>
> Don't remove the step start! It was added to protect the transformer,
> electrolytics and tubes, which was something the manufacturer should
> have done.
>
> It should be no big deal to make it work on 115V AC.
Stepstart relays need to have a DC coil instead of an AC coil so they
won't buzz the contacts when closing.
> Depending on the
> circuit, you may need to change the voltage-dropping resistor in
> series
> with the relay coil, but that's probably about all.
>
>
>
> --
> 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
> http://www.ifwtech.co.uk/g3sek
>
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>
R L MEASURES, AG6K. 805-386-3734
r@somis.org
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