[ARC5] FW: Way OT -- SX-28 - ARC5 selectivity

[William Cromwell]

Hi Hue..

..Everybody,

I had one of those Star Roamers once upon a time. It received CW and SSB 
by making the IF stage regenerative for selectivity and even more to 
serve as the BFO. Notice that it was NOT the detector as a TRF regen 
would be and was not as stable as a regen (I have and like regens). I 
didn't know any better back then and used it for several years. I 
acquired a Hammarlund HQ-145 and scrapped that Star Roamer! Any real 
radio would have the same result.

For my command receivers I use external audio DSP for a major boost in 
performance. Using SDR software in the audio chain also offers better 
fine tuning - even though the receiver is NOT modified for use with 
SDR/DSP software. You are using email which suggests the presence of a 
computer. You can make that work for you.

73,

Bill KU8H


bark less - wag more

On 8/7/21 12:10 AM, Hubert Miller wrote:
> Don't do this. It's only a parlor trick and you'll never be satisfied with the result.
> If you want to use regeneration, use a Q multiplier.
> Regenerative IF stages are crap, as numerous reviewers of the SX-140, Knight Kit Star
> Roamer, and so on have commented.
> -Hue Miller
>
>> Copied the following online.
>> Richard kn7sfz
>> Adding feedback to a 2nd IF stage to improve selectivity was sometimes
> used with the surplus "ARC-5" (vacuum tube) receivers in the 1950's and
> 1960's. One such approach was described in QST magazine (March 1960) by
> Lewis McCoy W1ICP "A Poor Man's Q Multiplier", available to ARRL members
> at arrl.org in the QST archives. McCoy indicated this improved
> selectivity considerably in the ARC-5 BC-454 (3-6 mhz tuning range; 1415
> khz IF) and ARC-5 BC-455 (6-9.1 mhz tuning range; 2830 khz IF).
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