The Hallicrafters S38C that I had as a kid, 1954, used a gimmick capacitor in the IF to affect the BFO. ?I thought it must have been a left over piece of wire, and learned the hard way. It took a bit of fiddling to get the replacement to function just right, and I learned to respect the masters who build such functional devices with few parts.
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On May 30, 2024, at 06:00, David Wilcox K8WPE via groups.io <Djwilcox01@...> wrote:
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Tisha,
Thats the issue. So many newer hams and electronic hobbyists didn't build the simple kits of the 1960s, etc., and never saw or used a gimmick capacitor. ? One of the 4SQRP Club kits used a gimmick cap recently (ie in the past 10 or 15 years). I just can’t remember which kit. ?Ha!
Be the REASON someone smiles today.
Dave K8WPE
On May 29, 2024, at 12:51?PM, Tisha Hayes, AA4HA <Tisha.Hayes@...> wrote:
?Steve,
Agreed, those input/output impedances have bitten me in the behind before; I had an engineering manager who believed that the software model was 'more accurate' than what we built on the bench and if the results were different it was because we were incompetent at actually building a circuit. Thankfully he was not long for the engineering-world and was quickly "promoted" to sales.
Like Hans had indicated, a model is a reasonable starting point but it eventually turns in to an exercise where the designer is hand picking components that are close in value and inserting them in to the circuit to come up with the accurate values.
You should look up the reference to something called a "gimmick capacitor". Sometimes I work on old radios and find one left behind; It is humorous when some other restorer either cuts it out or just solders the two ends together.
--
Tisha, AA4HA
