[Drake] Problem with L-4 power supply

[Garey Barrell]

Gene -

The HV is 1800 VDC in the CW mode, but should go to 2600 or so in the 
SSB position.

The Sunlight board is fine, and is a good upgrade.

You know you have to "key" the L-4B via the "VOX RELAY" connector on the 
back to transmit through the amp.?  Just short the two pins together, or 
if it's an RCA phono jack just short the center conductor to ground.  
About 30V @ 60 mA or so.

Also, the AGC knob on the front panel has to be pulled OUT.

If these don't resolve the problem, let us know!

73, Garey - K4OAH
Glen Allen, VA

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


MUCHSTUFF wrote:
> I have had this L4B and power supply for several years.
> I just decided to see how well it works
> It doesn't..
> No grid or plate current.  My drive passes through undisturbed.
> After messing around a bit, I switched to plate voltage.
> 1800 volts.  I believe it is supposed to be 2600 volts, no load.
> Removed the circuit board.  It is from Sunlight Energy Systems, dated March,
> 2005, about the time bought it.
> The board has no discoloration, no odors.
> Resistance is the same for each rectifier section, and for each filter
> section.
> As opposed to the Drake schematic, this board has a 100,000 ohm resister
> parallel to each diode.
> I have diodes and filters to replace the existing ones, but why should I?
> It is wired correctly for 120 VAC.
> The replacement board was correctly wired in.
> I have not measured the AC voltage out of the transformer yet. I have 4,5 or
> high voltage probes in obvious safe places.
>
> Addional question: Should the amplifier have worked somewhat with 1800
> volts.
>
> I would like to hear from anyone who may have had a similar problem.
>
> Gene Rippen,  WB6SZS
>
>
>