Al,
I have had a 6 mtr beam mounted above my TA-33 tribander in several different
installations for the past 40 plus years. There has been no significant
interaction between the two antennas (50 MHZ DXCC and WAS/WAC are the
proof…………DXCC Honor Roll on HF as well, all antennas never higher than 45
feet). The 6 mtr beam has been either a 4 or 5 element beam on a 12 foot boom.
My rule of thumb has always been to mount the 6 mtr beam 5 feet above the
tribander. If you need to mount the two meter beam on the tower, you could
follow Chuck’s recommendation below or extend the mast by coupling a smaller
diameter mast to the top of your existing mast. The two mtr beam has minimal
wind loading, so shifting down to a smaller diameter mast coupled to your main
mast would be ok for the 7 element beam.
FYI, when you mentioned that you tuned the antenna on the ground, just how
close to the ground was the antenna ? Was it in a horizontal plane, or was it
tuned on the tower and the tower folded over, so that either a director or
reflector was close to the ground ?
Good luck and hope to hear you on 6 mtrs once the Sporadic E season starts.
73,
Dave, K2DP
St. Louis, MO
> On Mar 23, 2021, at 6:00 PM, Chuck Dietz <w5prchuck@gmail.com> wrote:
>
> Try the 6m perpendicular to the C3 to see if that helps. It could be placed
> at the top of the mast for best separation and the 2m in the middle.
>
> Chuck W5PR
>
> On Tue, Mar 23, 2021 at 2:30 PM Al Kozakiewicz <akozak@hourglass.com> wrote:
>
>> Still have a foot of snow on the ground, so I'm not quite ready to climb
>> yet.
>>
>> See photos on QRZ page.
>>
>> I have 3 antennas on a 10' mast sticking a total of 8' out the top of the
>> tower. From top to bottom, 2M7, 6M3 and a C3, all equally spaced. All were
>> tuned to resonance on the ground.
>>
>> Now up in the air, the C3 and 2M7 are fine, but the 6M3 is useless. The
>> SWR is about 3:1 and Z=~70 ohms at the minimum for both.
>>
>> Is this symptomatic of interaction, i.e. feed point characteristics change
>> while resonance frequency remains the same? If so, what is a recommended
>> solution? The one possibility I haven't checked yet as it requires climbing
>> is a bad rotor loop cable.
>>
>> Al
>> AB2ZY
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