Quote:
Originally Posted by Philips210
I seem to recall some sets have two slugs in their IF transformers and are stagger tuned to give a broader response so tuning is not as sharp. The primary is tuned to about 2kHz below the nominal IF frequency and the secondary 2kHz above the nominal IF frequency. So peaking the transformer won't give the best performance.
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It would be interesting to see what forum members think of this.
There are a number of transistor radios that have double tuned IF transformers, a good one could be the Eddystone EC-10. And those typical vintage flat Philips one too in other radios. My understanding was that even though these are double tuned, they are critically coupled or close and the transformer has been designed by the manufacturer so that when the signal amplitude is peaked on both adjustment cores (just as they are done in a valve radio IF where these are often tuning capacitors) the correct bandwidth occurs due to the design of the transformer.
I have not actually seen any alignment instruction for radios where its suggested the IF's are stagger tuned to widen the bandwidth, but there may be some that do suggest this, has anybody seen this for any AM radio model where a sweep is suggested and a characteristic broadened response curve is required ?
I think gain and selectivity are the prime concerns in the radio, not bandwidth.