[HBR] Progess report and 50:1 drive idea

[Walter A. Hutchens]

Bill said:
> While 20:1 is not the 50:1 which is the subject here, it still
> takes 12 feet to cover the 180 degrees...does that still make it
> 20:1? 

I THINK so.   A sideband signal has to be tuned in within about 10-20 cps 
to sound right, doesn't it?   Neglecting the allowance for end effects, 250 
kcs spread over 25 revolutions to rotate a cap 180 degrees is 10 
kcs/revolution or a bit less than 30 cps/degree.   It does depend somewhat 
on the quality of your dial mechanism -- I can set the dial on an LM or BC-
221 much more precisely than a 6:1 planetary ball drive.   

Using a PW dial (12' scale length) gives you great ease of reading the dial 
and correspondingly good resetability, to the limit of your ability to 
accurately position it.  

20:1 would be ideal for an AM/CW receiver or for an SSB set with 100 kcs 
bands.   For 250 kcs, I think 50:1 is better.

One check point:  I have a two-speed Jackson Bros. drive on the R8040A.   
The 'fine' ratio is about 36:1 and those are 500 kcs bands -- 3500-4000 
and 6800-7300, with very little extra.   The calibration isn't too close to 
linear, so the ratio at the high C end (75 meters) could be around 20 or 
25:1.   That's too quick for me, even with a fairly large knob.

This list is a great resource.   157 members!  Who knew?   Thanks to all for 
the consultations and thanks to Kees for the list and the wonderful site!

Of course we're a rather tame lot.   No flame wars or even insults.   

That's to conjure with ... an HBR-list flame war.   What would the topic be?

Walt 
KJ4KV