Re: Is there a difference between a RF choke and a RF coil ?

Re: Is there a difference between a RF choke and a RF coil ?

I normally think of the RF choke as a large value coil specifically used to stop RF from travelling through it. An RF coil is any inductor used for RF applications, typically a small value, nH, used for matching, loading, etc. But both are coils, just different applications.

has.mac

Reply to
has.mac
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Both have inductive reactance but are applied differently. A coil is used as one element in a tuned circuit. An RF choke is used to decouple circuits from RF ... they act as low-pass filters and can be used to block or isolate RF.

The very same component could be either, depending on the application. Back in the bad old days of vacuum tube rectifiers, a filter choke was often used to block 60 or 120 Hz. ripple (so it does not have to be an RF application). Choke means to "choke off" the ac component that is not wanted.

Generally, coils are selected to have a higher Q (inductive reactance/resistance) and chokes often are selected for size/cost.

Reply to
Charles Schuler

I am wanting to shortin my RX wire on my RC radio sytem. The schematic I found calls for a 1.5 uh Coil, silver-Brown-Gold-Silver-Green You cut down the RX wire and leave 4 inches of wire on the RX, add the coil in series and add a 6 inch piece of piano wire. The RC radio in on 72 Mhz channel 22 ( 72.230 Mhz) The original length of the RX wire is 38 1/8 inches. I have found 1.5 uh RF chokes on Ebay, but not sure if they will work. I would like to tune the RX antenna to 72.230 Mhz as close as I can, to avoid signal loss. Thanks Remove nospam in email snipped-for-privacy@earthlink.net

Reply to
George

Yes, you can shorten an antenna by adding a loading coil (yet another name). You will lose some performance (range).

Here is a calculator if you want to make your own loading coil:

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(20 turns, 0.42 inches dia., 1 inch long is close). I'd suggest #18 magnet wire or something similar.

Reply to
Charles Schuler

Thanks charles That was what I was looking for to build my on base loaded antenna. I believe I have the #18 magnetic wire, just need to find a .42 core. This is for my RC helicopter , so the shorten range should not be a problem. I will try several different length of piano wire to determine best range reception starting at 6 inches. Thanks again

Reply to
George

So you posted to a slew of newsgroups, causing individual threads in each of them, and posted the question more than once to some of some of the newsgroups, when you could have picked the most appropriate and asked the specific question pertinent to your application than a vague quesion?

You could have picked sci.electronics.basics or sci.electronics.components and asked "I need a coil of XXX uH for YYY application, can I use an RF choke like I see in the catalogs, or do I have to wind something myself?"

Michael

Reply to
Michael Black

The guy asked a simple question, not how to post in the newsgroups How do you know which newsgroup is read by a RF coil expert ? How much does it cost YOU for every time he post his replies ? I have read the replies in four ( a slew) newsgroups and all gave an example of there applications. Maybe you can explain the difference between a 1.5 uH RF coil and a

1.5 uH RF choke ? Bob

Reply to
Bob

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