[Boatanchors] RBC Power Issues

[Anthony Quinn]

You'll have to extend me an invite to see your barn - sounds interesting

Sent from my iPhone

> On Sep 30, 2017, at 11:00 AM, David Stinson <arc5 at ix.netcom.com> wrote:
> 
> 
> 
> Meant to include this:
> 
> Don't have  an RBC power supply and the receiver power 
> 
> connector is missing in any event.
> 
> 
> The RBC is speced for 200 VDC general B+, 105 VDC Regulated for 
> 
> the Local Oscillator, 6.3 VAC general filaments and
> 
> 17 VAC, which is "regulated" through a Ballast Tube and
> 
> resistor circuit to provide 6 V to the LO tube.
> 
> 
> 
> Don't have that filament ballist tube.  Have had no trouble
> 
> just running the regular 6 V fil. buss to the LO, which was 
> 
> done by the previous person working on the set.  I'm thinking
> 
> of rectifying and regulating the fil buss to the LO, but doesn't 
> 
> seem necessary so far.
> 
> 
> 
> The 105 V B+ buss for the LO draws only 8 mills, so I 
> 
> installed a 12.5 KOhm 5 Watt resistor and a 100V, 5W Zener
> 
> to power that buss.  Works fine.
> 
> 
> 
> 200V B+ buss is easy to regulate these days with a MOSFET
> 
> and that will "leaven the whole lump."  Total current draw 
> 
> for the B+ buss is about 75 mills at full volume.
> 
> 
> 
> For those who prefer "Low B+," the set operates reliably
> 
> at 100V B+ on both busses.  Loses about 6 DB of Audio Output 
> 
> at 100V and a small but noticeable reduction in audio quality.
> 
> The BFO oscillator doesn't start reliably below about 75 VDC,
> 
> but the set will play AM down  50 V.  with, of course,
> 
> a reduction in audio output and quality.
> 
> 
> 
> Still chasing a few little "gremlins," but things are looking good.
> 
> 
> 
> Dave S.
> 
> 
> 
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