FM/AM Frequency Generator Recommendations

[Black Gate]

I am considering purchasing an FM/AM Frequency Generator to align my tuners (mostly solid state from the 70's). I like to tinker and a tuner alignment is about the only thing I am yet unable to do with precision when restoring my receivers. It seems this is a specialized area. Can someone recommend a brand and model of Frequency Generator I should be looking for, preferably used for around US$500 and suitable for stereo FM.

I already own a frequency counter, oscilloscope, distortion meter and a 20Hz - 20kHz tone generator. Is there any other piece of equipment I will need to align a FM/AM tuner? Will I need a sweep generator?

Many thanks in advance.

[Conrad Hoffman]

I use an HP8640B. They typically have some internal problems with the gears (cracks) and switches but if you find a good one, or are handy with restorations, it's a super unit with better performance than just about anything out there. The specs say 500kHz to 500MHz, but they actually (and intentionally) go down to 455kHz for IF alignment. AM and FM modulation is whatever you send into the modulation jacks, so if you can't do what you need, you're probably better off with a service type unit specifically designed for stereo tuner alignment.

Best,
Conrad

[firechief]

Ok
Here is one on ebray that looks like a good deal,
It will also do multiplex FM. It's fully synthesised and has calibrated output level.

NATIONAL PANASONIC VP 8177A FM/AM SIGNAL GENERATOR - eBay (item 370291633206 end time Feb-13-10 19:47:16 PST)

The manual is avaiable
http://www.freeinfostuff.com/Manuals...77a_owners.pdf

Just one idea

[Black Gate]

Thanks for that Conrad.

[Black Gate]

Originally Posted by firechief

Ok
Here is one on ebray that looks like a good deal,
It will also do multiplex FM. It's fully synthesised and has calibrated output level.

NATIONAL PANASONIC VP 8177A FM/AM SIGNAL GENERATOR - eBay (item 370291633206 end time Feb-13-10 19:47:16 PST)

The manual is avaiable
http://www.freeinfostuff.com/Manuals...77a_owners.pdf

Just one idea

I've had my eye on this unit firechief but it does not seem to handle a stereo signal, Being a newbie, I was not certain how important the feature would be.

[firechief]

I understand, perhaps someone could look at the manual and give us some enlightment. The FM stereo signal uses somthing called (I think) a 9Khz subcarrier, and it really isn't clear to me if that is included. We may both learn something.

[star882]

Nowadays, cheap FM transmitters often use crystal-referenced PLLs. Best bet to find one of those is to look for one with a digital frequency selector. If your frequency counter goes high enough, you can use it to verify accuracy.

[jackinnj]

Sencore SG-165 -- prices range all over the lot. There was probably a Heath or Eico unit as well.

[firechief]

Jackinni
In the specificions section of the manual for the Panasonic unit that is for sale on ebay states:
"Separation for MPX stereo signal: >55 dB (test tone 1 kHz, 75 kHz deviation, RF 76-108Mhz):
Is this enough information for Black Gate to be sure that he can test his classic FM receivers? This is a synthesized rig for sale for only 288 dollars, and while not one of the more well known models, If it will fit the bill, the price is right. Oh, I just took another look at the sale. Why the heck are they asking 175 dollars for shipping. Whats up with that?

[Glowbug]

Originally Posted by firechief

I understand, perhaps someone could look at the manual and give us some enlightment. The FM stereo signal uses somthing called (I think) a 9Khz subcarrier, and it really isn't clear to me if that is included. We may both learn something.

The pilot tone for MPX is at 15KHz, so that's why there's a brickwall filter slightly below that, to prevent chirping