02-25-2019, 12:10 AM
>I removed the 1st detector Philco ( part number 03015) coil from the model 90 .
<260 kc in model 91.
> may have the same issues due to the nitrocellulose insulator used between windings
Have not had an IF transformer apart from a 90 but typically the coils in an IF transformer are not wound one over the other but are two separate winding that are spaced apart from each other. Wouldn't need an insulator between the plate and grid coils. If you wind one over top of the other there is too much coupling between them. This causes poor selectivity. The further apart they are the sharper the selectivity but the less gain.
Bruce,
Come to think of it I have a spare National RAS (brother of the HRO) it has a 175kc IF. The chassis is beat I'll see I can find a good transformer
for you to tinker with. Are you good in qrz? I'll send it out when you get the 91 working [Image: http://philcoradio.com/phorum/images/smi...wisted.gif][Image: http://philcoradio.com/phorum/images/smi...on_lol.gif]
Don't know if you are active but you'd like to get together on 40mtrs sometime shoot me a pm.
GL
<260 kc in model 91.
> may have the same issues due to the nitrocellulose insulator used between windings
Have not had an IF transformer apart from a 90 but typically the coils in an IF transformer are not wound one over the other but are two separate winding that are spaced apart from each other. Wouldn't need an insulator between the plate and grid coils. If you wind one over top of the other there is too much coupling between them. This causes poor selectivity. The further apart they are the sharper the selectivity but the less gain.
Bruce,
Come to think of it I have a spare National RAS (brother of the HRO) it has a 175kc IF. The chassis is beat I'll see I can find a good transformer
for you to tinker with. Are you good in qrz? I'll send it out when you get the 91 working [Image: http://philcoradio.com/phorum/images/smi...wisted.gif][Image: http://philcoradio.com/phorum/images/smi...on_lol.gif]
Don't know if you are active but you'd like to get together on 40mtrs sometime shoot me a pm.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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