Tandy Discone scanner antenna

[G3aeme]

Hi members, I have a Tandy/Radio Shack Scantenna that boasts 25 to 1300 mhz but I have noticed that other versions have a vertical section on top about 30" long
with an inductor in the centre. My unit does not have this added vertical section. Can any member enlighten me on its use and can I build one?

 

[dlwtrunked]

The vertical element on some discones was added to improve reception on frequencies below or above the normal coverage of the discone. These added whips vary in what range they try to improve. Some try to get good coverage at 6 meters (~54 MHz); other try to improve 800 MHz range (as the usual discone cone-to-disk distance is too much for good coverage there). So you need to design the added whip for what frequencies you want to improve. By the way, I am not sure Tandy/Radio Shack sold an antenna with that name (another company did). Anyway, Tandy/RadioShack did sell a discone. It is well know for using hollow elements (unlike others)that break easily in the wind.

 

[rf_patriot200]

The vertical element on some discones was added to improve reception on frequencies below or above the normal coverage of the discone. These added whips vary in what range they try to improve. Some try to get good coverage at 6 meters (~54 MHz); other try to improve 800 MHz range (as the usual discone cone-to-disk distance is too much for good coverage there). So you need to design the added whip for what frequencies you want to improve. By the way, I am not sure Tandy/Radio Shack sold an antenna with that name (another company did). Anyway, Tandy/RadioShack did sell a discone. It is well know for using hollow elements (unlike others)that break easily in the wind.

Exactly. Mine broke too, so a trip to Ace hardware solved the issue, when I found Solid Aluminum stock ! I merely had to trim the length and tap the threads to screw back into the center hub .

 

[prcguy]

The Radio Shack Discone whip resonated sharply around 50MHz and did help improve reception below 100MHz at the cost of messing up the higher frequencies a little. If you don't need CB or VHF lo band I would suggest not installing one.

 

[G3aeme]

The vertical element on some discones was added to improve reception on frequencies below or above the normal coverage of the discone. These added whips vary in what range they try to improve. Some try to get good coverage at 6 meters (~54 MHz); other try to improve 800 MHz range (as the usual discone cone-to-disk distance is too much for good coverage there). So you need to design the added whip for what frequencies you want to improve. By the way, I am not sure Tandy/Radio Shack sold an antenna with that name (another company did). Anyway, Tandy/RadioShack did sell a discone. It is well know for using hollow elements (unlike others)that break easily in the wind.

Thanks for your prompt reply, it seems to me that if I experiment with different lengths of the vertical section, I might come across a solution of sorts. I have noticed on some brands of this antenna, there is a loading coil mid way along its length and was wondering what its inductance would be. so I could duplicate it in some way. The breed of discone that I have is an Archer Cat No 20-013, me thinking it was Tandy/Radio Shack only.

 

[prcguy]

The key to the vertical whip working on a Discone is a base loading coil that decouples the whip from the Discone in its native VHF/UHF range. Otherwise a whip can degrade the overall performance of the Discone in the VHF/UHF range.