[Boatanchors] LM-13 Frequency Meter

[Brian Clarke]

Hello Jack, and anyone else interested,

The LM and BC-221 heterodyne frequency meters are designed to produce very 
many harmonics. Consequently, they are not good for VFO service. Sure they 
are stable, and you can dial up a frequency quite accurately, at least 
within 10 to 15 Hz of the on-board calibration xtal (the limit of resolution 
is the lowest frequency your headphones can reproduce and that your ears can 
discern - to get 10 to 15 Hz, you need really good cans). As a driver for a 
VLF, MF or HF transmitter, you would need to add filtration to attenuate the 
harmonics. To produce a shop standard, I have upon occasion added a 6AK5 and 
a short antenna.

I have a few LM and BC-221 series with the correct frequency book, the 
calibrated crystal and all tubes. I even have one with all the spare tubes 
and a spare crystal. There are no extra holes, unlike Jack's one illustrated 
in his photobucket library. All the original components and wiring are still 
there - especially that wonderful Cardwell variable capacitor. I have one or 
possibly two mains power supplies for them. I have no need for so many het 
freq meters. So, if someone would like to make me an offer ....

73 de Brian, VK2GCE.

On Tuesday, July 22, 2014 12:28 AM, Jack said:


> LM-13 freq meter free for shipping from 66212. At the Warrensburg MO
> hamfest I saw this and thought it was a really neat looking item and
> would make a nice VFO. I am usually good at resisting temptation but
> every time I walked by that table it would whimper "buy me", "buy me".
> Anyway when I got it home this is what I found: The good news is that
> it has the original calibration book and actually works! The bad news
> is that someone had removed all the vacuum tubes and associated
> resistors and capacitors and had transistorized it but done a poor
> job. They had also drilled air holes in the cabinet. I note that all
> the critical components of the original meter are still there so I
> suppose it would be possible to re-install the tubes, sockets, etc., a
> job I am not interested in doing. Another option is that it would make
> a good parts source. Pictures at:
>
> http://s909.photobucket.com/user/jackholzer/library/LM-13%20Frequency%20Meter