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

[Garey Barrell]

Charles -

As long as it doesn't completely go out, it's ok.  It's a shunt regulator, which means that when the key is up and the 
oscillator isn't drawing any current, the 0A2 has to draw enough current through R4 to keep it's plate at 150 VDC.  Then 
when the key is down and the oscillator draws ~10 mA the 0A2 draws less current, keeping the voltage at 150 VDC.  The 
0A2 should regulate anywhere from 5 to 30 mA.  The resistor should be such that the 0A2 draws about 20 mA key up, for a 
total of ~30 mA.

If the filter capacitors are leaky, the B+ becomes low, and when the key is down there isn't enough unregulated voltage 
to keep the 0A2 'lit'.  Another possibility is that R4 has gone up in value, again limiting the available current flow.

A voltmeter on the Plate of the 0A2 should read close to 150 VDC with very little (volt or so) difference between key up 
and key down.

By the way, the schematic is wrong, R4 is 4.7k NOT 47k.

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>

Charles Ring wrote:
> My V-10 has a chirp which at 20 meters is really awful. Really fit only for use during the Classic Exchange.
>
> A new question: when the VFO is keyed, should the brightness of the 0A2 stay the same? Mine almost goes out.
>
>