Cap with choke question - Printable Version
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Cap with choke question - Shaleradio - 09-02-2018
My next project is a 41-220c. I have a few questions but my first is regarding the capacitor which I have pictured. It's listed as #9 and is a .25 mfd with choke. The choke is chassis ground. There's is a lot of rubber coated wire in this one and the choke is as well. Both need replaced but how do I go about this? I see no resistance listed for the choke even though it is wound around the cap several times. Can anyone advise me on how to couple a new choke properly with a new cap and if I should order a cap with the same .25mfd designation?
Thanks,
Mark
RE: Cap with choke question - Phlogiston - 09-02-2018
Just make the new one look like the old one - same number of turns.
RE: Cap with choke question - Shaleradio - 09-02-2018
So, it doesn't matter that the new cap will be a considerably smaller diameter and the resulting same turns of lead wire will be shorter in total length than the original?
Thanks for your response.
RE: Cap with choke question - Phlogiston - 09-02-2018
Not enough to worry about.
But if you have a uh meter (cheap from china) you could measure it. The metal foil under the paper tube will change the reading so it will need to be measured as an assembly and compared to the new one. I would not bother.
If you re-stuff the original cap the diameter of the coil could be preserved.
RE: Cap with choke question - Shaleradio - 09-03-2018
Thanks! I think I'll restuff the paper cap. I appreciate your information!
RE: Cap with choke question - amptramp - 09-08-2018
The idea of the series capacitor and inductor is that the capacitive reactance was still a bit higher than the designers liked so they changed it into a resonant circuit but with broad enough tuning that the reactance would drop below that of the capacitor alone in the frequencies of interest. If you are replacing the capacitor with a film cap, the inductance may not be needed.
RE: Cap with choke question - Shaleradio - 09-11-2018
Thanks, amptramp!