[ARC5] Drift in BC-453 - more

[AKLDGUY .]

The thread has meandered around because we haven't been given anything to
go on.
You have blamed the BFO but haven't mentioned any stability figure.

Is the B+ feed to the BFO tube original? Are the resistors good? Have they
been
replaced by significantly different values? Is the decoupling to it still
present? Are the
caps bad?

Sounds silly, but has a 6SR7 been fitted yet the heater line been rewired
for 12V? Are
you running 25V on the heater line and a wiring mistake has resulted in 25V
on the
12SR7?

I hope you've eliminated the painfully obvious.

Neil ZL1ANM


On Sun, Dec 17, 2017 at 3:50 AM, J Mcvey via ARC5 <arc5 at mailman.qth.net>
wrote:

> This thread has taken many meandering twists and turns.
> It all started when I suggested that BFO stability may be the reason that
> WSPR cannot be decoded with a commend reciever.
> Yes, it is a "hobby thing" where I aspire to make a complete 630 meter
> station from command components.
> One of the "Ham-mered' transmitters can be re purposed as the transmitter
> and the BC-453 as the receiver.
> The transmitter will be controlled by XCO or VCO with PLL.
>
> The computer systems drift ARE NOT the issue with WSPR. It works fine with
> other rigs.
> The BC453 LO "seems" to be stable if I leave it on a weak beacon station
> for a period of time.
>
> I built a 85 Khz fet Colpitts oscillator from some junk box components. I
> hope it will be more stable than the command set BFO, but
> it may have more phase jitter than I want.  We'll see...
> It will be used to drive the grid of the existing BFO oscillator
> disconnected from the set's BFO can. The plate circuit will remain intact .
>
> I haven't had time to do  the drift measurements on the BFO and LO yet,
> but I will get there eventually. Stay tuned...
>
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