10.7 MHz oscillator with transistor

[aurelZ]

Really?
I don't know from where you digg all that observation in a shape like "WallOfText"
Just to let you know ,i finished my high electronic school somewhere at the end of 1988.
And from then to now i have build many electronic projects.
fixing many electronic devices,TV,Receivers etc
So i am surprised about simple thing as is ceramic filter for 10,7Mhz which you can find
in almost any analog FM radio receivers ,car radios,satelitte receivers and i really don't get it what kind of data you need.
Here is the image of ceramic filter i use

 

[Audioguru]

The very simple 10.7MHz oscillator you posted in post #15 has an output which is AM and FM combined so it is a poor way to test an FM demodulator that is supposed to reject AM.

 

[aurelZ]

AM and FM combined so it is a poor way to test an FM demodulator that is supposed to reject AM.

Yes Audioguru , i can agree with that but don't forget that main purpose of
FM detector to pass only one carrier frequency which is 10.7 and as such this circuit is the
simpliest soulution.
In the past you must know there are some electronic kit-s with such a option.
As far as i can say ,for me this topic is finished.
all best...

 

[majoco]

Never mind connecting the oscillator to an FM IF amplifier - do you have a shortwave receiver, preferably digital, that you can use to search for your oscillator around 10.7MHz? Much better than a frequency counter as when you connect the counter to your oscillator, the frequency will change! I use a cheap Degen 1103 digital receiver for all sorts of things, setting the frequency of a tube signal generator, for example - very quick and easy, just listen for the carrier with the radio set to "SSB" on the frequency you want.

 

[bertus]

Hello,

You might want to try this circuit:




More circuits can be found on the page where the picture came from:
http://www.agder.net/la8ak/12345/n19.htm

Bertus

 

[aurelZ]

problem is already solved,look lat schematic

 

[WHONOES]

Had a look at your link and cannot find any mention of a ceramic trans-filter. Ceramic filter yes, trans-filter no.

 

[davenn]

Had a look at your link and cannot find any mention of a ceramic trans-filter. Ceramic filter yes, trans-filter no.

yeah, we had that one out earlier in the thread
Trans-filter seems to be some sort of screwball local definition to the OP
Everywhere else in the world of electronics they are known as ceramic filters

 

[hevans1944]

Everything that you need to know about ceramic filters can be found on this web page, along with links to other sources of information. Until these spiffy little devices came along, the filters they implemented were made from discrete quartz crystals, hand tuned to specific frequencies. It was an expensive and time-consuming process, so the filters were not cheap. Collins Radio came along later with their patented mechanically resonant filters, which were inexpensive but restricted to a much lower range of frequencies, typically 455 kHz, which was associated with single-conversion super-heterodyne receivers tuning from the AM broadcast band up to about 30 MHz. More about Collins filters here.

Above 30 MHz or so (there are no sharp boundaries) 10.7 MHz is a popular super-heterodyne intermediate frequency (IF), especially for broadcast band FM receivers. Communication receivers sometimes use it before down-conversion to a lower IF such as 455 kHz. This makes ceramic filters very much a popular design component for RF signal processing such as band-pass and band-stop filtering. However, I doubt anyone skilled in the art would ever seriously consider using them as a stable frequency-determining element. Better, simpler, more frequency-stable circuits are available. As usual, your mileage (or kilometers) may vary. Use whatever works for you.

 

[majoco]

VHF FM IF amplifiers need a bandwidth of about 180kHz (as shown on that MuRata pic) so how do we know where in that 180kHz the thing is oscillating?

 

[cdm889]

Finished circuit which is TESTED and work very well.
View attachment 45737

Indeed, this circuit works well, thanks!
I am just curious, why is circuit 9th harmonic (FM signal 96.3 MHz) has two sideband harmonics, one at 95.9 Mhz and another at 96.7Mhz? which plus or minus 0.4 MHz?

Mike

 

[aurelZ]

Thanks Mike ..i am glad that work for you and for me to,it is simple but do the job.