I was looking at the Schematic from PRR that shows 2 tuning tank circuits plus the detector coil linked to the second tank circuit.
That Radiola 16 PRR linked would use a triple ganged tuning capacitor. Otherwise, the user goes "nucking futz" adjusting things, when a station change is desired. As a youngster, I had a 3X 0-365 pF. ganged tuning cap. on my parts pile. Adjusting a ganged TRF setup for 1 particular station is NBD. However, getting good performance across the entire broadcast band is a different story. Armstrong's superhet allows "optimal" performance, at a single freq., the IF, to work well across the whole band. It's anything but surprising that superhet became dominant.
BTW, many (especially FM setups) superhet designs employ a TRF stage prior to the conversion stage not for gain, but for "image" freq. rejection. Remember, there a 2 frequencies that will heterodyne with the local oscillator to yield the IF freq, the desired station and its "image". Adding a TRF stage prior to the converter rejects the unwanted "image".
BTW, many (especially FM setups) superhet designs employ a TRF stage prior to the conversion stage not for gain, but for "image" freq. rejection. Remember, there a 2 frequencies that will heterodyne with the local oscillator to yield the IF freq, the desired station and its "image". Adding a TRF stage prior to the converter rejects the unwanted "image".
Hi All;
Tonight, I accidentally made a significant Discovery..
And because of it, I now know that one of my Variable Capacitors is 250 pf and the other one is 500 pf..
It came about when winding my coils and they wouldn't tune correctly, and so I tried what I had thought was my Antenna coil and my main coil and it didn't work..
So I reversed them, on a whim.. and I got a response..
I had also, originally thought my small variable capacitor was about 2 pf and my large one was 100 pf.. So, I started from there using Professor Coyle's site to re-calculate what I needed to get the response that I needed..
And so, that is how I could prove to myself exactly what size Capacitors I had, when the Calculations and the tuning both gave the same results..
I will let everyone know tomorrow, as I make more progress..
Here is the Link that I used --
Professor Coyle cylinder HTML Version copyright (C)2005 Darryl
Boyd
THANK YOU Marty
Tonight, I accidentally made a significant Discovery..
And because of it, I now know that one of my Variable Capacitors is 250 pf and the other one is 500 pf..
It came about when winding my coils and they wouldn't tune correctly, and so I tried what I had thought was my Antenna coil and my main coil and it didn't work..
So I reversed them, on a whim.. and I got a response..
I had also, originally thought my small variable capacitor was about 2 pf and my large one was 100 pf.. So, I started from there using Professor Coyle's site to re-calculate what I needed to get the response that I needed..
And so, that is how I could prove to myself exactly what size Capacitors I had, when the Calculations and the tuning both gave the same results..
I will let everyone know tomorrow, as I make more progress..
Here is the Link that I used --
Professor Coyle cylinder HTML Version copyright (C)2005 Darryl
Boyd
THANK YOU Marty
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