Littlefella
New Member
Call Sign : 26-CT-3508
Posts : 38
Times Thanked : 0
Join date : 2020-05-01
QTH or Location : Northbourne, Bournemouth
Equipment Used : Ss6900
 |  Subject: 2 antennas  Tue May 12, 2020 8:12 pm | |
| Hi all
I want to mount my 2 metre and my sigma venom on the same pole. They would be about 400mm apart and only 1 Would be used at a time. Would they interfere with each other?
Thanks in advance for any advice
73's
Gary | |
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Northern Crusader
Major contributor
Call Sign : M0GVZ / 26CT1760
Posts : 536
Times Thanked : 35
Join date : 2019-11-13
QTH or Location : IO94SA
Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike
Age : 54
| | Subject: Re: 2 antennas Wed May 13, 2020 2:14 am | |
| They'll affect the tuning of each other as they'll capacitively couple, the 2m antenna will be impacted the most. You'll find you need to shorten one or maybe both. Also the radiation patterns of the antennas will be altered too.
The other consideration is that the 2 metre amateur band is extremely close to being a fifth harmonic of the 11m band, the fifth harmonic of the 11m band falling just 5-6MHz below. This means that depending on how well suppresed the harmonics are on your 11m rig that if you run enough power, especially with a typical CB linear amp with sod all harmonic filtering, you could possibly damage the receive of the 2m set even if it's turned off. For that reason it may be worth fitting something like the Kenwood LP30 low pass filter which would attenuate any harmonics above 30MHz by 60dB or more.
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Littlefella
New Member
Call Sign : 26-CT-3508
Posts : 38
Times Thanked : 0
Join date : 2020-05-01
QTH or Location : Northbourne, Bournemouth
Equipment Used : Ss6900
| | Subject: Re: 2 antennas Wed May 13, 2020 7:34 am | |
| Thankyou for that. I didn't know the technical aspects of it but I was worried that one would jump on to the other. No worries, I'll put another pole up and keep them separate.
Many thanks
73's
Gary | |
|
Northern Crusader
Major contributor
Call Sign : M0GVZ / 26CT1760
Posts : 536
Times Thanked : 35
Join date : 2019-11-13
QTH or Location : IO94SA
Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike
Age : 54
| | Subject: Re: 2 antennas Wed May 13, 2020 4:11 pm | |
| If you're running legal 4W there shouldn't be an issue, other than the radiation pattern getting skewed mostly on the 2m, but I'm suspecting you probably don't intend to be.  | |
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Littlefella
New Member
Call Sign : 26-CT-3508
Posts : 38
Times Thanked : 0
Join date : 2020-05-01
QTH or Location : Northbourne, Bournemouth
Equipment Used : Ss6900
| | Subject: Re: 2 antennas Wed May 13, 2020 4:28 pm | |
| Might turn it up a watt or 2  | |
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