[Boatanchors] Heath Warrior bias supply (was WTB: 6.3VAC/20A and 10VAC/low current transformer)

[Ian Wilson]

120V isolation transformers used to be cheap and easy to find.
I had a quick look at some surplus outlets but didn't see what
I was looking for.

Another possibility would be to run a 120V/6.3V transformer
backwards. Since you have a handy 6.3V supply right there
this would seem like a cheap solution.

73, ian K3IMW


On Fri, Nov 21, 2014 at 8:08 AM, Rick Poole WA1RKT <wa1rkt at comcast.net>
wrote:

>
> Several people have answered me privately regarding the Heath Warrior
> filament/bias transformer, and one has offered to give me a 6.3VAC 20A
> transformer for the cost of shipping (THANKS!).
>
> Now I'm thinking, though, that I might not want to continue with the
> original bias circuit design.  That design provides a negative 4.5 volts of
> bias during operation, but does not provide for any internally-generated
> cut-off bias voltage during receive times... the exciter or some other
> external source needs to provide that cut-off bias of from -45 to -150 VDC.
>
> A previous owner of this amp had installed an internal antenna changeover
> relay (undocumented, of course), presumably so the amp could be used with a
> transceiver.  I'm thinking I might convert that to use a circuit more like
> the 30L-1, where the bias is supplied by a separate transformer (actually
> the 30L-1 uses a separate winding on the power transformer) and generates
> nominally -160 volts cut off bias, which also runs the antenna changeover
> relay so that when the relay is pulled in during transmit, the bias reduces
> to around -5 volts.
>
> Anybody see any problem with any of that?
>
> For that I'll need the 6.3VAC-CT transformer at 20 amps as before, but now
> I'll need about a 120VAC transformer for the bias supply instead of the
> 10VAC one, if anyone has one of those to part with.
>
> Thanks...
>
> Rick WA1RKT
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