radio shack discone scanner antenna

[barefootdipole]

i found a used radio shack discone antenna at a hamfest.....it was an older model without a vertical element for low band reception.

well, i found an adapter to go onto the top to hold a vertical whip.....and got a long whip to fit the adapter....

my question is, what optimum length should the vertical element be to add low band to the discone ????? or is it not at all necessary ?

thanks
Barefootdipole

 

[oZscan]

by adaptor you mean the loading coil ?

 

[hoser147]

Which RS discone do you have? here is a link to a antenna cutting chart. http://www.pandacomm.org/panda_march_05_017.htm Good Luck Hoser

 

[jonny290]

234/Frequency (in MHz) = quarter wave length in feet.
Err on the long side - you can always cut more off, but barring welding gear, you can't put more back on

 

[barefootdipole]

by adaptor you mean the loading coil ?

nope.
no loading.
no coil.
no loading coil.

just a ferrule adapter to add a whip.......

 

[barefootdipole]

Which RS discone do you have? here is a link to a antenna cutting chart. http://www.pandacomm.org/panda_march_05_017.htm Good Luck Hoser

no RS parts number on it (label may have worn off after years of outside exposure)......just 8 lower elements 32" long each, and 8 radials 11" long each...and a flat top where an exposed threaded bolt end allows screwing in a ferrule adapter so i can add a whip to enhance lo band reception......

nice chart, but it was for 138-900 Mhz only...not lo band.

i'll just revert to standard antenna element formula's.......

odd, the current RS discone with a vertical whip on their web site gives specs that the entire antenna is 44" long....thats not very tall for something claiming lo band reception and 6m transmit ! (like only an 11" vertical whip)

was just hoping that someone on here with an existing discone might have a general idea on what length their vertical element
might be for the lo band.....

i got a extra long whip so i can cut it for about a 6m quarter wave....

thanks
Barefootdipole

 

[barefootdipole]

234/Frequency (in MHz) = quarter wave length in feet.
Err on the long side - you can always cut more off, but barring welding gear, you can't put more back on

yup, standard formula.

and always cut off LESS than you think you should, just to leave a tuning fudge factor !

i need to learn some discone theory to see the exact relationship between the lower elements and the vertical.....

thanks !
Barefootdipole