Total posts : 45366
Hi All,
It may not be well known here, but there are always a ton of good quality oscilloscopes available on eBay for a couple hundred dollars or less that will serve the purpose better than any modulation monitor. An oscilloscope will allow you to view the actual modulation waveform, so you will not be at the mercy of whatever whiz bang modulation monitor design that comes along. I’m not knocking the AMM-HF1. It may be a very good unit for all I know, but you can do better for less money.
Go to ebay.com and search on “oscilloscope”. My recommendations are:
1. Don’t look at any of the older scopes that use tubes.
2. Look for a name brand like Tektronics. Models 465, 475 or 485 are good choices.
3. Be sure at least one probe is included.
4. Get interested only if the seller says it works and shows a picture with a waveform displayed.
5. Don’t be concerned about whether it has been calibrated recently or not. The absolute voltage reading isn’t important.
These scopes are very sensitive so a wire loop connected between the probe and scope ground will serve well for a pickup. Length of the wire depends on how far your TX is from the scope position.
Take a look at http://www.sstran.com/pages/sstran_fsscopepics.html for examples of under-modulation, 100% modulation, and over-modulation. These waveforms were taken by simply clipping the probe to an insulated antenna wire (no electrical contact).
