Hi Bill, NJ1H
See also
http://www.k3pgp.org/432filter.htm
This 432 MHz filter and protection device has a fraction of dB losses and so if fitted in front of a 70 cm preamplifier do not degrade very much it's Noise Figure.
You can build it very easily at home.
73" de
i8CVS Domenico
----- Original Message ----- From: "Bill Bordy, NJ1H " [email protected] To: [email protected] Sent: Tuesday, November 06, 2012 5:04 AM Subject: [amsat-bb] Phelps Dodge Cavity Resonator 406-512 MHz for mode J. Also request for info.
I am now on mode J with a transverter and my Flex-5000A. I picked up a Downeast 144-28 transverter at the local hamfest, and experienced overload on the 435 MHz downlink when transmitting on 2M. I had seen this before with my FT-736R
At a previous hamfest, I saw a Phelps Dodge Cavity Resonator marked 406-512 MHz and bought it for $1 thinking that it may resolve the overload problem. Well, I finally tried it in path for the 435 MHz .
Wow, great fix. I have it in front of my 435 MHz preamp and now have no movement of noise floor when transmitting on the 2M uplink.
It also has CAT NO 495-509 marked on it. Not sure about the second 5, could be a 3 since number is worn badly.
I did a WEB search and didn't find any technical information specific to this model. If anyone has information, would you supply me with a link or info?
If you can find one of these, don't pass it up. A single tuning adjustment on top. I peaked it during a FO-29 pass. I then discovered a local 435 MHz noise source, I think a cable distribution box, than I could peak on also. Fortunately it is only in one direction and beam has to be right on to see.
There may be other cavity resonators that would work.
73, Bill NJ1H
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