[ARC5] BC-454 Conversion

[Dennis Monticelli]

Someone mentioned an AA5 output XFMR and that is what I have used
successfully  The impedance on the primary is a little low for a
reduced voltage ARC-5, but you don't have to load the secondary with
the typical AA5 3.2 or 4 ohm either.  I load it with 8 ohm and this
makes for a higher reflected impedance and a better power transfer.
Marty also mentioned the B+ dividers, a pair of series 7K resistors
that reduce the B+ for biasing the screens.  The radio will definitely
run better on low B+ without the divider.  If you lift the ground leg
of the bottom resistor to allow this (vs shorting out the top
resistor), then you get a bonus.  B+ current drops so low that a
string of 9V batteries can be used to power the radio for a long time.

Dennis AE6C


On Dec 24, 2007 7:47 PM, Ian Wilson <ianmwilson73 at gmail.com> wrote:
> I have had no problems running any of BC-453, BC-454, BC-455 on 90V B+.
> This seems a reasonable compromise, no need (usually) to replace caps, but
> also no problem with getting the oscillator to work reliably across its range.
>
> There is no need to mutilate the front panel or the dynamotor connections:
> all the connections you need are brought to the rear connector. As someone
> has mentioned, mini banana plugs fit this well. You can drill a thin piece of
> plain PCB or other plastic, and use it to mount the mini banana plugs to make
> a complete 'connector' if you like.
>
> I experimented with a few transformers and found something that is a reasonable
> match to a small 8 ohm speaker. The volume is OK in a quiet room. I usually use
> an amplified speaker, though. You can make a small seperate chassis that has
> a power supply, gain pot, BFO on/off, and audio amplifier.
>
> 73 es welcome to the list,
>
> ian K3IMW
>
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