[Amps] Clipperton L soft

[Joe Subich, W4TV]

 > Here's what I see;
 > On CW, the Vp meter shows 700 volts.

700 Volts sounds awfully low.  The Clipperton L used 4 x 572B tubes with
a plate voltage (unloaded) of 2300-2400V in SSB and 1500-1600V in CW as
was typical in the SSB/CW switching of the day.

Perhaps someone converted the amplifier for 4 x 811A tubes and changed
the power supply to a half wave rectifier instead of a voltage doubler.
Check the tubes then carefully check the power supply.

73,

    ... Joe, W4TV


On 7/20/2017 5:58 PM, Kelly Taylor wrote:
> Hi all,
> 
> Just trying to diagnose a weak Clip L.
> 
> Here's what I see;
> On CW, the Vp meter shows 700 volts.
> The transformer, when isolated, reads five ohms to the low-power tap and eight ohms across the entire secondary
> The filter caps each start out showing short then gradually charge to then read the 100k of the parallel resistor.
> The diodes read low resistance forward and out of range reverse.
> The "fuses," two delicate resistors in series with the plate choke, and the choke itself, read very low in resistance
> Thinking I shouldn't trust the internal meter, but wary of servicing it live, I checked the values of the three resistors in series acting as a divider for the meter (each is off by 30%). The meter shunt resistor, again, isolated, reads within one per cent of spec.
> 
> I don't want to drop $300 on tubes only to find nothing's changed, and don't want to drop $100 on a Harbach kit only to find it was just the tubes all along.
> 
> Someone's been inside here before me; the electrolytics are not factory and there's some not-entirely-professional soldering, but the connections all seem fine electrically.
> 
> Is the off-spec condition of the meter dividing network just a diversion from bad tubes?
> 
> There's no evidence of any component having let out its smoke.
> 
> 73, kelly, ve4xt
> 
> 
> Sent from my iPhone
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