I already knew about the issues given forth about using a center taped heater
transformer with bias voltage feed on the center tap- and its a minor issue. Im
trying to divide and conquer my metering issues. Either my Meter is out of spec
or the Manganin wire is. Guess i could just simply jumper it with some high
voltage wire and see if the metering goes to scale and might even be past
stopper. http://en.wikipedia.org/wiki/Manganin
Mike
KC7NOA
> Date: Mon, 1 Mar 2010 07:53:48 +0000
> From:
> To: amps@contesting.com
> Subject: Re: [Amps] Mangian wire
>
> The GS35b has an indirectly heated cathode, tied to one side of
> the heater. The connection from your bias circuit needs to go to
> that point, not to the centre of the heater transformer. The way
> you describe the connections, you're adding AC to the bias voltage.
>
> Steve
>
> > Ok .. do you really need the Mangeian Wire from the B- of the Filter board
> > to
> > the shunted amp meter?? I have my amp up and running with a GS-35b now and
> > im
> > sure that my bias isnt working right .... mabey it is ... but as it sits
> > now ..
> > i should have 30V bias keyed and im showing 60ma idle ... now this is why i
> > think i still have a problem with metering - when driving with 30W im
> > getting
> > an output of 600W (carrier/cw -what ever) and the uA meter is showing only
> > about 120 mili-amps of plate current.
> >
> > Second question is do you need plate voltage on the plate to complete the
> > bias
> > voltages (im talking through the tube) to the heater?? My DC at the heater
> > is
> > 120VDC cutoff and 4V DC key'd state (no drive). My Bias supply is not
> > sagging
> > and the collector of the pass transistor is tied to the center tap of the
> > heater transformer ...... Please leave out comments about using a center
> > taped
> > heater transformer and the differences of using a bifilar wound rod for RF
> > blocking - its simply what i have and plan on using for now.
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