[Boatanchors] Globe (WRL) V-10 VFO - Problem with voltage regulation

[K9FFK]

Jerry:
The  0A2 current range is 5 - 30 mA at 150 Vdc.
At +175 V you would want an 833 ohm resistor to start (no load). (25V 
drop, 30 mA)
Even that may be too high.
A 47K resistor will only allow 3 mA regulator current...below minimum spec!

Try subbing an 0B2 if you want.
Or use a 560 ohm, 1W.

I think that 47K is a typo..should maybe have been 470.

Dick, K9FFK


On 11/8/2013 4:10 PM, D C _Mac_ Macdonald wrote:
> Try the regulator to give you 105V regulated with the specified dropping resistor.  I'd bet the VFO would run just fine with the lowered B+ voltage.  IIRC that's the 0B2.
>
> 73 - Mac, K2GKK in OKC
>
>
> Sent from my iPhone
>
> On Nov 8, 2013, at 15:51, "Jerry" <jsternmd at att.net> wrote
>
> I found a V-10 in great shape but someone had cut the line cord close to the
> chassis which made me worry that there were some potentially serious issues
> with the VFO.  The inside looks new, however before applying power, I
> checked to make sure the power transformer was not shorted.  The xfrmr works
> fine supplying filament 6.2vac and separate 175vac to a half wave selenium
> (65ma) that I replaced with 1n5408 plus a 200ohm dropping resistor.  I also
> replaced the two 30uF lytics and left the large (~10mH) choke between the
> two filter caps as it was not shorted either.  Thes B+ supplies the plates
> to 6BH8 and 6CB6 using a 0A2 voltage regulator.  I cannot get the 0A2 to
> strike at 175vdc from the filtered supply.  I replaced the 0A2 twice with
> known tubes and still not striking.   The dropping resistor between the B+
> and 0A2 is 47K, 1W per the schematic but in the VFO I found a 560 ohm 1 watt
> instead.  I cannot tell if this was done by the previous owners to get the
> 0A2 to strike earlier or if this was a factory mod not documented on my
> schematic.   Can anyone offer advice?
>
> 73 Jerry
> K1JOS
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