Powdered Iron Slug Source for 27MHz Circuit - Page 1
Forum section: electronics / projects

author: fuzzoli
author_rank: Regular Contributor
timestamp: May 16, 2020, 03:41:43 am
content: Does anyone know where I could find a source of threaded powdered iron slugs for a simple 27MHz transmitter circuit? The dimensions are:3/16" Dia. x 5/16" Long (for the crystal controlled oscillator)1/4" Dia. x 1/2" Long (for antenna matching)I'm in a cloning mode...more details of the project to come as I take more pictures.Thanks!-Frank

author: Benta
author_rank: Super Contributor
timestamp: May 16, 2020, 06:25:59 pm
content: At 27 MHz, it's certainly not powdered iron, but ferrite.Apart from that, you need a better camera

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 16, 2020, 07:03:05 pm
content: That looks like a picture of a page in a 1970s ARRL handbook.

author: cdev
author_rank: Super Contributor
timestamp: May 16, 2020, 07:22:20 pm
content: slug inductors come with those kinds of cores in them. They can be removed. They must be standardized.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: May 16, 2020, 07:38:13 pm
content: You can find them surplus-https://www.surplussales.com/INDUCTORS/IND-SLUGTU/IND-SLUGTU-6.HTMLThe best bet is usually buying complete coil forms with slugs. I also find them at hamfests and such, though there may not be any hamfests for a while.

author: Benta
author_rank: Super Contributor
timestamp: May 16, 2020, 09:00:40 pm
content: Quote from: Alex Eisenhut on May 16, 2020, 07:03:05 pmIt certainly does, although a 1960s RC aircraft magazine could also be the source. Lousy solder joints btw.

author: fuzzoli
author_rank: Regular Contributor
timestamp: June 16, 2020, 01:41:57 am
content: Last week I received sample slugs fromMicroMetals. The engineers over there were a great help! The slugs match the sizes as defined in parts list, so they'll be a good starting point.@Benta, @AlexEisenhut, the image is a scan from a B&W manual from, yes, the early 70's! I'm sure the Handbook photos were just like the one above.Regarding the solder joints...not my build. If I could find my actual device, I would becuriousscared to see the soldering job of me as a 10-year old.So what's the big reveal?Back in the 70's, Estes made a Model Rocket Transmitter kit called the TRANSROC. It was a 27MHz transmitter that pulsed the carrier (in rocket-finding mode), and among other things, could transmit audio. It was a neat little device for its time. I have the manual, but the actual transmitter must have been misplaced over the past 40 years or so.I'm going to build one.Why? Because I can (with some help from the forum I'd expect -- RF isn't my strong point). I'm going to make it as close to the original device as possible. So far, in addition to the slugs, I've obtained most of the old semiconductors. In the next week or so I'll start a new thread documenting the journey.To sort of stay on topic here, does anyone have suggestions on what to wind the coils on? The slug threads are standard screw sizes, so I was thinking of taking the correct size screws, wrapping and gluing several layers of thin (parchment?) paper to the desired diameter, and then cutting to length.Any other thoughts?Thanks,-Frank

author: cdev
author_rank: Super Contributor
timestamp: June 19, 2020, 11:26:41 pm
content: Why dont you use the actual coil forms that use those kinds of slugs?A number of online "surplus" oriented electronics stores offer "grab bags" of miscellaneous inductors. When I was starting out I bought a bunch of grab bags and lots of the parts ended up being very useful, among them were adjustable inductors. I still have a bunch. They tend to be pretty cheap and fairly useful.Some use those hex styled cores, I could probably find some and photograph them.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 20, 2020, 12:22:14 am
content: That's cool, I had the film-based AstroCam which took one picture at altitude as the parachute ejected. Loaded with 110 film.One day a C6-5 motor blew up on the lauch pad and blew the entire camera dozens of feet into the air.That was the end of that because Estes wisely chose to make that particular rocket a non-standard tube size.The only good thing about all this was the cute blonde at the one hour photo lab.