[Heath] LMO rebuilding....did I mess it up?

[G3OOU at aol.com]

Hi Ken
 
You are quite correct about the limited travel of the LMO tuning capacitor. 
 It is much easier to provide a linear frequency law over a restricted 
range  rather than all 180 degrees of travel.
 
All of the LMOs in my SB units are from TRW. The tuning capacitors and worm 
 drives are in excellent condition and only require any dried grease to be  
removed and replaced with new lubricant to give them a new lease of life.
 
73

Bob

Bob F Burns G3OOU,  G-QRP 6907, @BobFBurns
Crystal Palace Radio & Electronics Club: _www.g3oou.co.uk_ 
(http://www.g3oou.co.uk/) 
Technical web site: www.qsl.net/g3oou  

 
In a message dated 14/03/2016 01:42:33 GMT Standard Time,  
kgordon2006 at frontier.com writes:

On 12  Mar 2016 at 20:08, Guy Giacopuzzi wrote:

> reading (and receiving)  it on 7181khz...Did I do something wrong with 
the LMO?  I checked it's  
> range of movement,and with the tuning unit dialed all the way  
counterclockwise, the  variable 
> cap is almost closed; then, five  turns to the right and the cap is fully 
opened, as I recall.  I didn't  
> check it on any other bands, but at the moment, it would seem the  LMO's 
output is 219khz too 
> low....right?   It's reading 219khz  low exactly on both bands..... 
Help....

Guy: What seems odd to me is  your "range of movement". As I remember 
it, the tuning cap in the last  Heathkit LMO I worked on only moved over a 
fairly small range of tuning,  not the entire capacitor's tuning range. As 
I 
remember it (and it has been  several years since I rebuilt an LMO) the 
range of movement was only about  1/3 the total available range.

But H_eathkit used at least two different  makers of LMO, so perhaps yours 
and mine are by different makers. I think  the one I was working on was a 
TRW.

Now, as for your dial reading  219 kHz low, that sounds like the dial has 
either slipped, or the hub has  broken.

Have you measured the output of the LMO itself? It should be  5.0 to 5.5 
MHz with a little "overlap" on both ends. Something like 4995  to 5505 kHz 
total.

Also it will read the 5.5 MHz at the low ends of  the bands, and the 5.0 
MHz 
at the high ends: it "tunes  backwards".

Ken W7EKB  
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