I need help on building a FM detector

Status
Not open for further replies.

arveen

New Member
I dont know which one to use. I thought of the foster seeley discriminator but have no values. The modulated frequency is 150MHz
 

Attachments

  • foster_seeley_circuit.gif
    8.6 KB · Views: 622
This is a last 10.7MHz IF-stage of commercial FM receiver.The construction for 150MHz not impossible, but very diffcult and need a wobblerscope for proper adjusting.
 
Sebi said:
need a wobblerscope for proper adjusting.

That's not the correct English word Sebi, but I know EXACTLY what you mean - but I can't remember what it's called!. I seem to recall it's a very similar word, but having read 'wobblerscope' I can't get that name out of my mind

But as for the circuit, we really need to know what he's trying to do, it's rather vague! - as you say, you wouldn't normally detect directly at 150MHz (which is round about the 2M band) - but down convert to an IF of 10.7MHz. You would also usually use a far more modern detector, this is probably pre 1940's technology (not counting the IF transistor of course, which isn't part of the detector).
 
Heh, yes that term came back to me also, we had a really ancient piece of gear in my high school electronics lab called a wobbuloscope. Tube based instrument, designed just for alignment work. Sort of a cross between a oscilloscope / spectrum analyzer. It and the signal / sweep generators with the "eye" tubes were very neat to use.
 
Nigel

The word you are looking for is wobbulator.

Jim GM3ZMA
 
It's nice Nigel, i'm sure, You always understand my bad english.. (i never learn it, just read many datasheets and watch TV.. unfortunately in my country must be learn russian in scool)
Anyway, i have a scope with in-built wobbulator and the name on it "wobblerscope". (hungarian product, maybe the designer also learnt only russian....
 
Sebi said:
It's nice Nigel, i'm sure, You always understand my bad english.. (i never learn it, just read many datasheets and watch TV.. unfortunately in my country must be learn russian in scool)

Your English is pretty good!, a wobbulator is a very obscure device, I doubt it's often mentioned when learning a foreign language :lol:

I had to learn French at school, but I was rubbish at it!, though my daughter is currently being taught Spanish at her school.
 
Status
Not open for further replies.
Cookies are required to use this site. You must accept them to continue using the site. Learn more…