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Title: Making a Halli SX-62B from a SX-62A Post by: AB3FL on February 13, 2013, 09:28:20 AM I am trying to add the AFC circuit from the Halli SX-62B to my SX-62A. The schematic shows a 1n3182 varicap/varactor diode doing the dirtry work. The NTE replacement is NTE614 which I have. I have wired everything up exactly as the SX-62B, but it seems to be working as an anti AFC. It only works on Band 6(52-108MC). It is fed from the Discriminator which would be at 0 DCV when everything is properly tuned. When I turn on the AFC, it jumps up or down too far. Example if I zero the discriminator it will jump to roughly -1.6VDC or +1.6VDC. It will never lock at zero. The diode is not backwards. I have attached the SX-62B skizmatic
thx Tom - AB3FL Title: Re: Making a Halli SX-62B from a SX-62A Post by: AB3FL on February 13, 2013, 03:37:17 PM I got it working. Damn discriminator. Hardest thing to align even with a Heath IG-57A sweep generator and a scope.
Tom - AB3FL Title: Re: Making a Halli SX-62B from a SX-62A Post by: Edward Cain on February 13, 2013, 05:54:45 PM Hi Tom,
Can you tell us more about what the problem was. I may try this mod on my 62. Thanks, Ed Title: Re: Making a Halli SX-62B from a SX-62A Post by: AB3FL on February 16, 2013, 10:31:38 AM What is the nominal voltage swing on the outpooot of the discriminator? AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Tom-AB3FL |