[HBR] eBay NOS NATIONAL VELVET VERNIER DIAL ICN, Ham Radio (item 26002332...

[N2EY at aol.com]

In a message dated 8/24/06 9:32:21 AM Eastern Daylight Time, 
waltah at earthlink.net writes:


> >  I found this National ICN type on "that E site"... 
> > 
> > It's number 260023324900
> 
> That's a nice one, all right.   It was at $24 when I looked, last 
> night.   
> 
> The issue with these dials is that they have a 5:1 ratio which is 
> fine for coverage of the usual ham band if you are building a 
> receiver for AM and CW only as was the usual case ~1960 but gives a 
> VERY fast tuning rate for SSB -- over 200 kcs/revolution if covering 
> all of 80-75M, for example.

IMHO. 200 kc per revolution is way too fast for CW as well as SSB. In fact 20 
kc. per revolution is almost too fast. This is particularly true if the 
receiver has decent selectivity.

I suspect that many classic receivers had such fast tuning rates for two 
reasons:

1) Good slow dial drives were expensive and scarce.

2) The way hams operated back then was very different. Many hams used rigs 
that were not very frequency-agile, and operating split was the rule rather than 
the exception. You would call CQ and tune the entire band looking for 
replies. (This is also why old-time operating used such long calling sequences - they 
gave time for you to find answers). With such operation, you needed to be 
able to get across the band fast.

All that is changed now.

> 
> I like the JB/Miller 6:1/36:1 two speed drives for this sort of 
> application.   You can use them with a modified National dial or make 
> your own dial, which could be as simple as a metal frame with a 
> cardboard face.
> 
> Or, with a few more hours of work (hey, it's a hobby ...) you can 
> make a sandwich consisting of a piece of your dial face, a 1/4" 
> plastic spacer around the edges, a 1/32" plastic cover, and a metal 
> frame as before.   Cut the metal frame so it overhangs the dial face 
> at the upper corners, you can drill through the panel behind the 
> overhangs to put in lamps (or LED's?).  A 3/32" plastic pointer fits 
> easily in the 1/4" allowed by the spacer.   With careful work and a 
> nice paint job (TEST ON A SCRAP BEFORE PAINTING PLASTIC) it will 
> equal the best of them for both looks and function.  
> 

Or, use a disk of plastic and a fixed pointer.

--

But there's an easier way.....

The tuning capacitors from surplus ARC-5 transmitters and receivers, as well 
as the LM and BC-221 series of frequency meters, will do a better job than 
almost anything else. They all have integrated antibacklash gear-drives, and 
built-in dials.

Best of all, you can usually get a junker-but-good-for-parts ARC-5 or 
LM-BC-221 for less than $24.

73 de Jim, N2EY