Fw: [HBR] Progess report and 50:1 drive idea

Tue Apr 25 09:42:15 EDT 2006

One of the best no backlash high ratio drives is still the tuning
mechanism out of a BC221 Frequency Meter which always show up at
swapmeets.
The Command Set anti-backlash gear sets are also great but the gear ratio
is higher and you have to get mechanically creative to use it.

73 Kees K5BCQ

--------- Forwarded message ----------
From: "Don" <dkelly42 at cox.net>
To: <hbr at mailman.qth.net>
Date: Tue, 25 Apr 2006 07:07:09 -0700
Subject: [HBR] Progess report and 50:1 drive idea
Message-ID: <000a01c66871$8b5e8b20$a84d6144 at lindseyk1p8m17>

Walt,

"Does anyone have experience with string drives at ~50:1?   What about a
5:1 
ball drive and a 10:1 string drive?"

Walt I tried what you mentioned above not long ago. Good idea.

I used a 2" drum and 1/4" shaft. This gave me 8:1. I also mounted a
drive from Dan's Small Parts. See EPICYCLIC CORD DRIVE NO. 4413. It
inclused a 5:1 panel mount drive. I panel mounted the drive shaft
coupled to the tuning shaft. That gave me 40:1. My tuning range was 400
Khz and the tuning was pretty nice but had to be aligned perfect.

http://www.danssmallpartsandkits.net/

I rebuilt the VFO and reduced the tuning range to 70 Khz for CW and did
not need or use the drive again. This particular drive has only 8oz
torque. I don't think it is 1st class quality and would not have trusted
using it long term unless I did some better mechanical construction. The
small drum is not made well as the coupling is not dead center. 

However, Jackson Brothers has a similar 5870 drive with a similar output
torque but I expect much better construction. The trick is in the
alignment. 

http://www.mainlinegroup.co.uk/jacksonbrothers/index.htm

Maybe a source of ideas or parts for future projects. I want to try the
5670 drive sometime.

I like the homemade string drives. They don't wear out and you can
always find a replacement. But can be a difficult mechanical problem to
install.

BTW, I wrote an article 20 years ago about a string mechanisms using a
jar lid for the drum if anyone would be interested.

K5UOS

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