u/vtfrotex

Just got this radio in for service.

Can anyone confirm that the model is correct?

I've worked on tube radios and 70s/80s solid state gear, but not an early SS piece like this.

Pretty neat unit. It has a well-built chassis. But, as typical, plagued by failing/failed electrolytic capacitors.

Before, all you heard was hum through the speakers, now it plays lovely music. I might have to grab one of these for the collection.

Note: The first image is not mine, but it is the same radio.

Anything radio never gets old to me. Somehow I missed this TA7642 radio on a chip until I came across it via surplus. I thought this might make a neat project for for an EMI sniffer. AM is great at detecting the various noise/trash thrown off by modern digital electronics. I find it a fascinating alternate world that you can explore, given the right tool.

There are various plans around the internet for projects with the TA7642, including an application example in the datasheet. So, coming up with a design is really easy.

Keep in mind that this is a prototype and there's tons of room for improvement.

On the left side of the board is the power/audio section, to the right is the RF.

I opted to exclude a tuning capacitor and go with fixed SMD capacitors on a dip switch. I know it's dirty, but for my application it's fine. Now I can switch-tune to various frequencies to get the best response to EMI and keep the overall footprint smaller.

It runs on a single AAA battery with about 1.3mA of current draw, which means it will run a very long time, some 500+ hours.

What became apparent while I was building it is how tiny you can actually make it. With custom boards and SMD components, this sucker will shrink down a ton. I'll probably revisit this idea sometime in the future.