HFU HF Underground
Technical Topics => Equipment => Topic started by: Erik Mattson on February 03, 2022, 1748 UTC
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Received a Tram 1411 discone to poke around the VHF/UHF neighborhood with, and to use with my Uniden SDS-200. To listen to something OTHER than local PD/FD (Balitmore County, Project 25 Phase I).
This thing's pretty nice, but started putting it together and then realized it's not going out the door fully assembled. ;D It's raining anyway.
Ah! And it's super nice that it fits perfectly in the end of a chain link fence top rail (1-3/8" dia.)
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I had a Tram 1411. I bought it with the thought of being able to use with my SDR receiver and for 2M/440 TX, I wasn't all that impressed with the receive or transmit. I Never tried to use on 10 meters and imagine it wouldn't have been a great performer. I think a medium sized 2M/440 vertical works better. I have a Diamond X200A and I'm quite pleased with it. If you are going for just receiving over a large spectrum of VHF/UHF then you'd probably be happy with a discone. I paid around $90/$100 for the X200A and it's built very well. I was quite surprised when I received and put the 1411 together, its a beast!
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I have used one in the past and it had worked OK. The discone can provide wide frequency bandwidth. The problem with a discone is the pattern looks up. Discone was initially developed to work with airplanes. If you are interested in airplanes then a disconne works well. However, it is satellites, then a discone can leave something to be desired. For terrestrial paths, it is a bit of hit and miss. A fan of dipole antenna is sometimes better for scanners. This type of antenna should be available for scanners. It is a suggestion.
However, since you have a discone, then put it up and see what can be received.
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Oh yeah... Bought my 1st Discone in the late 80's as a scanner antenna. On VHF High and UHF, that worked great, but kind of sucked on VHF Low band, but the documentation did dictate that, so I knew it before hand. It was the 1st one to come out from Radio Shack at the time. Then, when I'd gotten my Code-less Tech Class HAM ticket, in 1991, it was my 1st multi-band 2M / 222MHz / 440MHz antenna. However, being made out of aluminum, those GND-radials keep breaking off. Today, I have the Diamond D-130J Discone, with 6M FM VERT stinger, all made of stainless, and that has held-up through hurricane force winds well. That, and being a low-gain antenna, it works well to get me out of the bottom of this current river valley location, where high-gain antennas fail, by taking advantage of reflection and refraction. So, it's my main VHF / UHF simplex base antenna. Also, works very well on the five MURS channels, but has a high VSWR match on 462 / 467MHz on the GMRS FREQ's.
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If it has a 3/8" connector on top for a 6m-band vertical like many discones do, you could consider replacing the vertical with a common ~9' whip to improve reception well down into HF frequencies.
A discone has no gain, but assuming RFI/EMI is low in your desired mounting location, a remote preamp could be of benefit. A remote preamp also can help offset feedline losses, which can be quite prevalent at VHF/UHF frequencies. Unless you are doing something exotic like EME - not likely with a discone ;) - even a basic OTA TV remote preamp should suffice if feedline losses are an issue.
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I own several, they are ok for receiving local stuff, are ok for using on a scanner, are ok for transmitting on the police, fire, ambulance bands here, but for amateur radio I had to go to a hamfest and buy a second vertical whip and extend the whip by about 6 inches and trim a little off the radials until it was tuned for 2 meters / 70 cm.
The downside is - it may be ok for receiving some 6 or 10 meters, but it will not transmit on those frequencies. I own a Diamond and a Tram and don't see much of a difference between the two.
And sometimes the Trams were made by Diamond and sometimes the Diamond antenna was made by Tram.
To get decent performance out of the antenna, you need to get it at least 10 feet higher then everything else in the neighborhood.. This includes buildings, houses, trees..
And you need to feed it with the best low loss coax.
If all you are going to do is use it to receive I would suggest that you purchase some Belden quad shield TV antenna coax and some good connectors. 75 ohm doesn't matter if all you use it for is receiving.
If you don't have the money to buy good coax, you could search the local TV Cable dumpster, they throw miles of coax away, along with connectors. You might find a length of RG 11 with the F connectors already installed.. Which would be even better, then all you would have to do is buy two adaptors to connect it to the antenna and receiving radio.
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I have to admit I have discone envy and hope to someday get my mitts on this: https://titanmissilemuseum.org/museum/ham-radio-operators/ (https://titanmissilemuseum.org/museum/ham-radio-operators/) Wonder what it would do for my IC-705 qrp rig.
There's also this: https://www.youtube.com/watch?v=HQSC08ej1dU (https://www.youtube.com/watch?v=HQSC08ej1dU) Not sure if the radio club on the USS New Jersey gets to use the discone on the bow, I think they're restricted to the whips on the superstructure, but hope to find out someday if I'm in that neck of the woods.
One thing I've liked about my discone (forgot where I bought it, had it for years), is it does great yeoman work for scanning. While I do have various antennas cut for specific things, (air band, 1090 MHz, marine VHF), it's great for a wide range of frequencies for drop of the hat moments. Agreed the pattern is "up", but it's done a lot for me over the years as a wideband omni, and still serves as a backup trainsmitter antenna too.