[ARC5] Using WSJT-X with R-23 or BC-453B

[Kenneth G. Gordon]

On 2 Nov 2017 at 20:56, J Mcvey wrote:

> 
> I'm running it on a 24V DC supply and dynamotor..
> However , it's NOT regulated ( it's n old PBX supply.)
> 
> Since these are heaters with cathodes, why is it so sensitive?

I don't know, but it is.

> The BFO osc is a triode (12SR7), so no screen.

Correct. Also the BFO is operating with very low plate voltage.

> Of coarse,  the 12K8 is another story.

Yes. IMHO, the 12K8 is possibly the absolute worst of its type for noise. There are some 
fixes for that, but I have never yet used any of those. One replaces the 12K8 with a plug-in 
adapter using a 12AT7. Another uses a pair of 7963 subminiature triodes in a Pullen 
configuration. 

The 12AT7 mod, as I understand it, works very well as long as the RF stage is peaked up 
on one particular frequency. For some reason, it doesn't "track" well across a band. 

No one that I know of has yet used the Pullen configuration, but that one SHOULD be both 
unusually quiet, and very stable. It should also track well.

> I ran both these radios on a HP 8935 for about an hour and it did seem stable AM 
> tuning wise.
> I measured the P-P output on a scope to see if there was any change. however I 
> could hear changes while using the BFO. maybe my methods were ineffective...
> What do you use as a regulator? Zener? cold cathode type?

I use cold-cathode types, simply because I like the pretty colors. In point of fact, Zeners 
work better, take up less room, and are cheaper.

Ken W7EKB



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