[ARC5] ARC-5/R-25 tuning gang question

[Kenneth G. Gordon]

On 4 Feb 2016 at 2:05, J Mcvey via ARC5 wrote:

> 
> The original "modification" used a 75 pf mica to compensate for the missing
> plates on each section.This is a bit too much, to be able to tune high enough to
> cover the whole 160 meter band. The trimmers needed to be completely out of
> mesh. I changed them to 50 pf micas which alowed proper adjustment to be made at
> about 50% trimmer mesh.

Good job! Well done.

> I'm just following up on the original mess to see how it
> would have worked. Since the dial is now  useless,

Well, actually, what the OT used to do is to paint the printed-surface of the 
dial white then hand-letter the correct frequencies in place. They used what 
amounts to a very fine-point Magic Marker to do the job. If you are careful, it 
can look very good.

>  I may prefer to replace
> the boogered up Gang anyway.

Well, finding such a cap might be a problem, but maybe it uses the same 
cap as one of the receivers for a different band uses: like the 3 - 6 MHz job, 
perhaps?

> So far the receiver still has a usable signal
> down to 0.1 uv in cw mode and maybe a little less! 

Yes. My tests of a refurbished BC-453 and of a refurbished BC-454 show 
sensitivity on CW to be about the same as you have found.

In fact, I have a BC-454 here which was (badly) converted to cover 10 
meters, and after I refurbished it and got it working, its sensitivity on 10 
meters was around 1 microvolt on CW. I was amazed!

Ken W7EKB