Re: Denco (science)
I think there's a degree of undeserved mystique about Denco coils, in the same way that some people go all squiffy and pay ridiculous prices for early-60s Germanium transistors.
In days-gone-by I built a 1.8/3.5MHz converter using Denco 'T' coils: OC170s for the RF amp and frequency-changer, 1.6MHz IF to feed into a car-radio. I never managed to get it to 'track' properly over the entire waveband despite weeks of fiddling with padder-capacitors well outside the Denco-recommended values.
The antenna-coil also seemed all wrong - there were too many turns on the input-winding and it was too-loosely-coupled to the tuned winding. Maybe OK for a broadcast-radio being fed from a random-length wire antenna but wrong for a 50-Ohm resonant dipole: I eventually reworked it as a 3.5MHz-only radio with a 3x25pF tuning-capacitor, stripped-off the original antenna-input winding and wound abot 10 turns of wire directly on top of the tuned-winding - which worked *a lot* better!
I think a lot of 60s/70s designs specified Denco coils just because they were 'out there' and avoided the need for constructors to wind their own coils.
The results were, I feel, mediocre.
As an impoverished kid/student I never managed to save enough to buy an amateur-bands-only Electroniques QP166!
|