On 11/22/2017 09:54 AM,
pf...@aol.com wrote:
> What is your wallplate voltage?
>
> 110:195 = XXX/260 where XXX = 147 VAC.
> 110:210 = XXX/275 where XXX = 144 VAC.
> 110:3 = XXX/4.8 where XXX = 179 VAC
>
> These results are reasonably self-consistent as what comes to a volume-control can have many variations. Note that increasing capacitance in many cases will also increase B+ and other down-line voltages, and generally *SHOULD NOT BE DONE*, especially in radios with field-coil speakers such as that one.
Using my DMM on the "AC" setting, out of the wall it's reading 124 VAC.
> So, hazarding a guess at long distance, you have a combination of high wallplate voltage, excessive capacitance and measurement variance.
>
>
> This voltage of 14X seems extreme, but given that these sets were measured with VTVMs back in the day, and VTVMs load very differently than a modern VOM. And the vintage unit was not "true RMS" and so could measure low. Do you have an old analog meter? Or, perhaps a VTVM?
>
> I have long-since learned to distrust factory-schematic voltages. Generally. I will bring a radio up to 110V on the Variac and measure secondary voltages off the transformer (unloaded, then loaded) to see what is what. If I get consistent discrepancies, I attribute it to measurement variances. If I get inconsistent discrepancies - more than 15% apart - I will look for a bad transformer winding or some other problem of that nature.
>
> Did you replace the line-filter cap on the line-cord? Do so with a type Y safety capacitor. That will help on reception.
>
> I have no idea where you are, but if you are anywhere near southeastern PA, USA, I would be glad to test your tubes. I keep both a little Simpson emissions tester and a Hickok 539B for the heavy-duty stuff.
Thanks for the offer! I'm currently in Providence, RI most of the time
so a little far, unfortunately...:(
> Otherwise, try swapping tubes with another radio. 6A8s are notoriously prone to failure, and glass ones are getting quite scarce. More so than even a 1L6 in my experience.
>
> Peter Wieck
> Melrose Park, PA
>
Will do. Yeah, gosh, NOS 6A8Gs are expensive! The schematic specifies
either the metal or "G" shape enclosure, I guess the GT doesn't have the
correct pinout? In any case, all the tubes currently fitted in the set
are the metal enclosure type.