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

[Richard Knoppow]

    I think this is the same trick Hallicrafters used in the 
later S-38 (starting with the S-38A I think) also in the National 
SW-54 and probably many other receivers. Eliminated needing a 
separate tube for the BFO. If was made regenerative and the AVC 
was disabled. On my S-38B it sort of worked.

On 8/7/2021 5:09 AM, William Cromwell wrote:
> 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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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL