AM modulation monitor wanted

[rickradio]

It's extremely rare for me to start a thread, but I'm hoping someone can help me out here. I'm looking for a used AM modulation monitor in good working condition for my Part 15 AM. I almost got a Potomac Instruments on eBay a while back, but the moron who sold it to me had a brain fart and shipped it to someone else after I'd paid for it thinking it was me he was shipping it to (or so he said). He did refund my money, but I still don't have a mod monitor, can't find anything else decent on eBay, BSW's prices are insane because they want to turn a healthy profit on everything they sell, and Radio Engineering Associates, even when begged and bribed, can't be persuaded to build any more of their monitors, even though their website touting said monitors is still up (but saying that they're sold out). Can anyone point me in the direction of one that someone doesn't want anymore and won't charge a price that includes a vial of blood? I'm all I got (I don't have a network bankrolling me). Thanks for any and all help.

 

[druidhillsradio]

Why not buy a used O-scope? You can easily couple some RF into it and make your measurements. That's what I do here. Works great.

http://www.am1000rangemaster.com/setmod.html

Hope this helps.

 

[RadioMan203]

The oscilloscope is a great way to measure modulation as I do that on the bench when troubleshooting or evaluating AM transmitters for my web site. The fact I have easy access to both Belar AM and FM mod monitors just makes it a little easier to test things on the bench since I can get both a visual indication of what's going out as well as a handy audio output.

I think I commented to your query in the Engineering section that the least expensive mod monitor I've seen in recent days are a couple of sellers blowing out the DaySequerra M2 AM/FM analog & HD mod monitor for around $600 on ebay. I had a lackluster experience with the DaySequerra service department in sending an M2 back for warranty repair. You may get a deal on one but be prepared for an expensive repair if it falls out of warranty.

If you get something like one of the Belar AMM 2 or 3 series you'll definitely need the companion RF amplifier to drive it. The monitor needs a couple of watts of RF sample to operate correctly and you'll never get that from a Part 15 rig. I actually keep a couple of Belar AM RF amps around tuned to different test frequencies as they are fixed, single frequency units. Keep in mind if you pick up an amplifier and need to retune it you're into the cost of a crystal, possibly a front-end coil set and, unless you have a scope and meter to do it yourself, a shop alignment charge. Also, stay away from the AMM-1 monitor as they are crystal controlled in the front end and I don't think they worked (well) in the X-band, which is where many Part 15 operators favor due to less congestion.

A sample loop and a used scope sounds like the most cost effective if you aren't equipped with the funds to pull all the pieces together.