[Heathkit] HR-10 Improvement on 10/15 ?

[MICHAEL TALLENT]

It would be easier to add the FET amp where the received signal goes to the 
mixer grid, you have the benefit of 2 stages of selectivity in the first RF 
stage and just adding some broadband gain might be enough to help on the 
higher bands.  You could possibly have a broadband peak in the FET gain only 
on the higher bands so as to not have to much gain on the lower bands, like 
a non-resonant inductor with a resistor in series to set the lower frequency 
gain and a resistor across the indictor to limit the high frequency gain and 
help broadband the response.

Mike   W6MXV

----- Original Message ----- 
From: "Paul Baldock" <paul at paulbaldock.com>
To: <heathkit at mailman.qth.net>
Sent: Friday, November 25, 2011 3:20 PM
Subject: [Heathkit] HR-10 Improvement on 10/15 ?


>
> I have an HR-10 that I am restoring to work with my DX-60. Like most
> (all) HR-10's it is deaf on 10M and 15M. This appears to be due to
> the scheme of using the 2nd harmonic of the oscillator on those.
> bands. The trouble is that there is not very much second harmonic.
>
> So I was thinking of adding a FET buffer to the output of the
> oscillator to generate some harmonics. Unfortunately a simple clamp
> would generate a square wave which only has odd harmonics.  A 1/4
> width pulse train generates a healthy 2nd harmonic, and maybe could
> be implemented.
>
> Any thought on this or other ideas to improve the second harmonic?
>
> Thanks
>
> - Paul