WEAK-AM

Now that I’m happy with the audio performance of my SSTran, I’m going to start working on modifications in earnest! NOTE: None of these modifications will affect the input power to the final stage!

Now that I’m happy with the audio performance of my SSTran, I’m going to start working on modifications in earnest! NOTE: None of these modifications will affect the input power to the final stage!

In the works:

1. Frequency adjust trimmer to allow the carrier frequency to be set precisely on channel.

2. Improved output match efficiency using a large iron-core toroid instead of the small axial-lead inductors. I just ordered up some #15 material toriods from Amidon Associates. The toroid should still fit inside the enclosure.

Planned:

1. On/Off switch

2. Remote metering for the output

3. External access to the output trimmer capacitor

4. Reduced adjustment range for the Compression pot to limit it to 1:1 – 2:1 and make it easier to choose low compression ratios

5. Negative peak LED to indicate when the carrier is being modulated at -95% or greater

I’ll let you know how it turns out!

Meanwhile, I have to say that I don’t agree that Part 15 AM can’t be used for high fidelity transmission. My SSTran sounds great on classical music now, and so does my Rangemaster. Listening on a high quality AM radio is an amazing experience! The SSTran signal is plenty strong enough to give excellent reception anywhere on my property, and the Rangemaster pushes that out to a couple of blocks. Sure, as you get further away, the audio quality drops due to noise, co-channel interference, etc. but it still sounds good and these impairments do not really spoil the enjoyment of the music until the signal gets very weak.

I have been a longtime devoted listener to classical music on AM over CBC Radio One (until they took it off the air last year) from CBL-Toronto (now off the air) and CBW-Winnipeg. AM radio is very usable for classical music, especially if you’re actually interested in the music and not just listening to the equipment. There’s a commercial classical AM station in Kansas City, KXTR (1660) that I hear from time to time. So it definitely can be done!

Part 15 is, in fact, a great place to experiment with high quality AM because we aren’t forced into a need to over-process the signal in an attempt to be louder than everyone else on the dial. Don’t get me wrong, though– some processing is good, and if someone offered me a used Inovonics 222 at a good price, I would probably be inclined to pick it up!