Saturday, March 28, 2020

Broadband scanner discone antenna for transmitting

Last month I bought a Tram 1410 Broadband Scanner antenna to use with my RSPduo. That receiver has a very broad range and I lacked an antenna to make use of any frequencies above 54 MHz.



I wanted to be able to copy the occasional FM "EasySats" as well as the International Space Station, non-trunked public service channels, NOAA fax transmissions on 137 MHz and whatever else might get my attention above the 6 meter band.

Reception has been quite well even though the antenna is mounted only 6 feet above the peak of my roof on a chimney mount. I'm able to copy many of the AMSAT satellites as long as they are above 30 degrees in elevation; and I can also receive aircraft transmissions while they are still on the ground, 11 miles away.

The ad for the antenna says that it is suitable for transmitting on several V/UHF ham bands. I was skeptical of this, but, to my surprise, it does indeed present a low SWR on the three bands I am able to sweep with my nanoVNA (soon to be upgraded).

Here are the results of a 100-470 MHz sweep:
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6 Apr 2020: 6-meter plot added:



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5 comments:

  1. The RSPduo covers up to 2 GHz. I wonder if the antenna has any performance up there, but it may be a moot issue due to loss in the coaxial cable, if it comes from any distance. I suppose RG/6-U quad-shielded would work OK for medium runs under 50 feet?

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    1. I've got a 50-foot run of LMR400 going to the antenna - quite a bit of loss even well below 2 GHz. But what is there to listen for at those frequencies?

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  2. Hi whats the swr 0n 6m band? Whith discones you can transmit there I suppose 73

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    Replies
    1. Added, see image, above. Not very useful on 6m. The SWR doesn't get below 2:1 until you go up to 100 MHz.
      73 - John

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  3. Tks, for me a discone with reasonable swr at 50 it'll very convinient. I wonder if some other discones permits readjusting 50Mhz some research needed 73

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