Click each question to see its answers.
What voltage are these rated for?
Asked by Anonymous on August 1st, 2016.
Uhm, I would NOT use this for making an antenna tuner for a high powered linear RF amp, but it does work nicely for 200 Watts or less, preferably 100 watts barefoot. KI7AQJ ham radio, luthrie & custom guitar, bass, keyboard, acoustic guitar & hi fi amps. I can get my ATAS 1200 antenna working down on 80 meters using this, and that is at best a 40 meter antenna. That is awesome!!!
Oh, and NEVER use anything like this with a loop antenna. Those can spike into the 1000s of volts, and you should use a 6KV vacuum capacitor with a loop antenna, unless you are running QRP. (less than 5 watts) Breakdown in air should be maybe a couple hundred volts. You could try to buy some mica and cut it to fit in the air gaps.
The maximum voltage is 350Vrms according to the information above.
Which knob should I use with this capacitor?
Asked by Anonymous on December 3rd, 2015.
Any knob designed for a 1/4" solid shaft that uses a set screw should work.
This variable capacitor has a higher end value of 365pF....can you tell me what the lowest end value is?
Asked by Anonymous on January 18th, 2017.
Hi, according to the info above the minimum capacitance per section is 14.9pF.
Is this a good choice for a crystal radio?
Asked by Anonymous on June 30th, 2017.
This would be an acceptable choice for a crystal radio.
What is the maximum operation frequency?
Asked by Anonymous on March 15th, 2018.
You will need to wind a coil or two or three, or more. Do some math! I think minimum frequency is more applicable. You should be able to run up to UHF with this, and down to 40 meters or more, 7MHz. Maybe 3.5MHz. Almost no one tries 160 meters. 6 meters has been dead for months. (50MHz) AM broadcast is just below 160 meters. 550 KHz-1.5MHz. You can put a cap in parallel with this, and make it larger. There are lots of free calculators for RF on line. KI7AQJ
What is spacing of the plates (this will tell me the voltage rating which IS an issue to me)
Asked by Anonymous on August 22nd, 2018.
Hello, the air gap is 0.010 inches wide from plate to plate.
Are these made in the USA?
Asked by Anonymous on March 19th, 2019.
Yes, these are made in the USA.