3
$\begingroup$

I'm looking to start building various antenna tuning circuits, but I'm limited by my parts inventory. I have pots and mag wire for winding inductors and a nice spectrum of fixed-value capacitors, but I have no high-voltage parts, nor variable parts.

The instructions I find online for mag loop antennas, in particular, require high-voltage variable capacitors. I'm still grappling with the theory to understand exactly what voltages are involved, but tuner circuits I'm finding around the web also involve variable caps/inductors.

Where do I find these parts for sale, or are they reasonable to build at home? I've been to a couple of local swap meets, but they're almost entirely PC parts, software, and manuals from the 90s. No vintage radios that I could find to pirate parts from.

$\endgroup$

closed as too broad by PearsonArtPhoto Jul 1 '15 at 11:54

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ I think the best bet is a hamfest (ham radio swap meet). I was just at one a couple of weeks ago and I am going to another in a week. All the hamfests I attend have lots of HV variable capacitors available and other things. But, sometimes, you have to buy some old junked home-brew tube linear to get access to the parts you need. Other sources include Mouser Electronics (they carry some HV stuff), RFParts (reparts.com), and even RF Concepts for parts available for Alpha amplifiers. Call up RF Concepts people and ask them where they buy there HV components. $\endgroup$ – K7PEH Feb 27 '15 at 17:14
  • 1
    $\begingroup$ If your local swap meet is mostly PC parts, software, and manuals from the 90s you are DEFINITELY going to the wrong swap meet. There are a variety of hamfests in the Bay Area so just go out and find them. Or, come up to the northwest. One of the largest is the Mike & Key ARC Swapmeet in Puyallup, WA (east of Tacoma, WA) on March 7th. Also, the best, in my opinion, is SeaPac, first weekend in June, Seaside, Oregon. $\endgroup$ – K7PEH Feb 27 '15 at 17:19
  • 1
    $\begingroup$ I'm voting to close this question as off-topic because it's a shopping question. $\endgroup$ – Phil Frost - W8II Feb 27 '15 at 19:25
  • $\begingroup$ I bought mine on eBay. $\endgroup$ – siliconwafer May 1 '15 at 13:02
  • $\begingroup$ Voting to close again...still a shopping question. $\endgroup$ – Phil Frost - W8II Jun 1 '15 at 15:37
0
$\begingroup$

They are not cheap, but they can be found. http://www.ebay.com/itm/Vacuum-Variable-Capacitor-10kV-10-500pF-HAM-RADIO-NOS-/391061938848?pt=LH_DefaultDomain_0&hash=item5b0d1ba2a0

This guy as a lot of good info on mag loops. I plan on coping his design one day. http://www.nonstopsystems.com/radio/frank_radio_antenna_magloop.htm

$\endgroup$
  • $\begingroup$ To make this answer useful, you should quote some relevant info from the website you cite. $\endgroup$ – W8AWT Feb 28 '15 at 0:57
0
$\begingroup$

Bob VE3UK is a machinist and makes some really nice butterfly capacitor components which he sells pretty much at cost.

He runs the Magnetic Loop Antennas Yahoo group. If you join that group you'll find a lot of information on Mag Loops and their components. Look him up on QRZ.COM for more of his info.

The Yahoo group is here:

https://groups.yahoo.com/neo/groups/MagLoop/info

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.