eHam

eHam Forums => Misc => Topic started by: W9BVG on September 23, 2017, 08:36:30 PM



Title: Adhesive for Use at Radio Frequencies
Post by: W9BVG on September 23, 2017, 08:36:30 PM
Anybody know of an adhesive with good dielectric characteristics at 3.5-30 mhz? I need to secure an air-wound coil to a plastic strip, but I want to be sure the adhesive won't short the coil windings at these frequencies. I've read that polypropylene hot melt adhesives are good for this purpose, but I think availability of those is minimal.


Title: RE: Adhesive for Use at Radio Frequencies
Post by: G3RZP on September 24, 2017, 01:11:12 AM
I found that some of the 5 minute epoxies produced no measurable drop in Q. But not all....The epoxies for long term structural use such as Araldite were another matter altogether.


Title: RE: Adhesive for Use at Radio Frequencies
Post by: DL8OV on September 24, 2017, 04:18:39 AM
Most epoxy resins seem to be fine and so far as I can see the cyanoacrylate adhesives (A.K.A. Crazy Glue) are totally transparent at RF. If in doubt about glues and plastics put a small sample in the microwave oven for a few minutes and see how warm it is afterwards, the good stuff should still be cool.

Peter DL8OV


Title: RE: Adhesive for Use at Radio Frequencies
Post by: N8YX on September 24, 2017, 06:04:10 AM
We need some of that stuff for a certain ham's (promised) billboard.

Let us know what you find.


Title: RE: Adhesive for Use at Radio Frequencies
Post by: SWMAN on September 24, 2017, 09:22:55 AM
I think that Cheese Glue would work good in this application, give it a try.


Title: RE: Adhesive for Use at Radio Frequencies
Post by: K2OWK on September 24, 2017, 04:54:57 PM
Gliptol

73s

K2OWK


Title: RE: Adhesive for Use at Radio Frequencies
Post by: WZ7U on September 24, 2017, 08:31:31 PM
As long as it's the winter blend....


Title: RE: Adhesive for Use at Radio Frequencies
Post by: K8AXW on September 24, 2017, 09:18:49 PM
As someone here on eHam likes to say, "WOW!" 

I've wound many air coils for antenna tuners and transmitters on pieces of Plexiglas and either ran the wire through holes drilled in the Plexiglas or simply used model airplane glue to hold the windings in notches filed into the edge of the Plexiglas.

I suppose this is what is meant by "ignorance being bliss."


Title: RE: Adhesive for Use at Radio Frequencies
Post by: W4AMP on October 27, 2017, 03:07:22 AM
(https://i.pinimg.com/736x/2d/0a/28/2d0a2899228f0f807e325caf934e8f81--doge-shirt-doge-meme.jpg)


Title: RE: Adhesive for Use at Radio Frequencies
Post by: AA4HA on October 27, 2017, 06:48:13 AM
Hot-melt is pretty common in tacking down coils to forms, I have also used it when making baluns.


Title: RE: Adhesive for Use at Radio Frequencies
Post by: K4JJL on October 27, 2017, 08:26:27 AM
(https://i.pinimg.com/736x/2d/0a/28/2d0a2899228f0f807e325caf934e8f81--doge-shirt-doge-meme.jpg)

(https://i.imgur.com/zcFfgG2.gif)


Title: RE: Adhesive for Use at Radio Frequencies
Post by: KAPT4560 on October 27, 2017, 02:55:54 PM
 I looked up Q-dope and found this forum:
http://www.redwaveradio.com/5_1afd3a8e8ab985c4_1.htm
 There are more dope links to be found at the bottom of the page.
 I have used a coarse lathe feed setting to cut a groove into a plastic tube for a coil form. I also bend air-core coil windings at work to tune them. They are rigid enough to hold position through the vibration and temperature tests that come afterwards.
 A red varnish is dabbed onto them to both hold the coil windings and also to indicate to further radio build technicians that the tuning step was completed.