Mikejo
Member
I built and arrow J-Pole using plans I found online....(you know the one, 3/8 aluminum rod, a 1" x 1" x 5 inch piece of aluminum angle etc.)
I shortened the elements for the Railroad frequencies (160.000 MHZ) range.
Connected up with 10 feet of RG58/U with SO239 Connector at the antenna, a BNC connector for my scanner.
(also made an in line Balun, about 1 foot back from the antenna connection, of about four turns around a 4 inch diameter object).
Ran it all through my antenna analyzer, and depending on how I moved it, I got readings for the best SWR of about 1:2 to 1 anywhere between 159.300mhz and 162.000 mhz
As I was trying to fine tune it to get a better swr, I began checking everything and discovered that my piece of coax had a little bit of the "black death" in it, so I decided to replace it.
I replaced it with an 18 foot piece of RG8x, it had two S0239, connectors, so I put a gender changer on the scanner end (SO 239 to BNC) also made an in line Balun (same as above).
So now, I run the whole mess through my analyzer, and I'm getting in SWR of 1:16 to 1 at around 132.300 MHZ. Wow!
Here is where all the problems began, no matter what I do, it stays between 132.300 MHZ and 137.000 MHZ. I have the long shaft made up of two pieces which I can separate, so I took one 2 foot piece off… Same results! I replace that, and remove the short piece (the 17.5" stub) completely and get roughly the same thing? I removed the short piece completely, and still get roughly the same thing? In other words, no matter what I do, I get readings within that same range.
I tested everything, looking for shorts in the new piece of RG8x, no shorts, it is good.
I connected to 50 ohm dummy load, and I get 50 - 52 ohms.
I checked the SO239 to BNC adapter for shorts, it's good.
Made sure all the connections are tight and making good contact... good!
I advanced the frequency into the 160.000MHZ range on the analyzer, and I get roughly 1:2 to 1.
So I'm perplexed, no matter what adjustment I make I can't get that antenna to show resonance anything above 137.000mhz on my analyzer.
Analyzer is a SureCom SA-250.
What could be the problem?
(Please don't just tell me that 1:2 to one is Great, I know it's ok,....I want it better...!)
I want to know also, why am I getting these weird results with the analyzer... (It works fine with other antenna's).
I shortened the elements for the Railroad frequencies (160.000 MHZ) range.
Connected up with 10 feet of RG58/U with SO239 Connector at the antenna, a BNC connector for my scanner.
(also made an in line Balun, about 1 foot back from the antenna connection, of about four turns around a 4 inch diameter object).
Ran it all through my antenna analyzer, and depending on how I moved it, I got readings for the best SWR of about 1:2 to 1 anywhere between 159.300mhz and 162.000 mhz
As I was trying to fine tune it to get a better swr, I began checking everything and discovered that my piece of coax had a little bit of the "black death" in it, so I decided to replace it.
I replaced it with an 18 foot piece of RG8x, it had two S0239, connectors, so I put a gender changer on the scanner end (SO 239 to BNC) also made an in line Balun (same as above).
So now, I run the whole mess through my analyzer, and I'm getting in SWR of 1:16 to 1 at around 132.300 MHZ. Wow!
Here is where all the problems began, no matter what I do, it stays between 132.300 MHZ and 137.000 MHZ. I have the long shaft made up of two pieces which I can separate, so I took one 2 foot piece off… Same results! I replace that, and remove the short piece (the 17.5" stub) completely and get roughly the same thing? I removed the short piece completely, and still get roughly the same thing? In other words, no matter what I do, I get readings within that same range.
I tested everything, looking for shorts in the new piece of RG8x, no shorts, it is good.
I connected to 50 ohm dummy load, and I get 50 - 52 ohms.
I checked the SO239 to BNC adapter for shorts, it's good.
Made sure all the connections are tight and making good contact... good!
I advanced the frequency into the 160.000MHZ range on the analyzer, and I get roughly 1:2 to 1.
So I'm perplexed, no matter what adjustment I make I can't get that antenna to show resonance anything above 137.000mhz on my analyzer.
Analyzer is a SureCom SA-250.
What could be the problem?
(Please don't just tell me that 1:2 to one is Great, I know it's ok,....I want it better...!)
I want to know also, why am I getting these weird results with the analyzer... (It works fine with other antenna's).