[TowerTalk] AV-640 (was GapChallenger ComparisonTesting Studies)

[Roger (K8RI)]

Art Trampler wrote:
> I’m going to beg to differ on the theory of operation of the AV640,
> specifically its native impedance and the use of the 4:1 unun (yes, it's
> wired as a unun).
>   
You are correct that the impedance is stepped down from 200 and not up 
from 12.5 which is what I get for going from memory. OT OH that the only 
spot where I see we disagreed.

My AV-640 is at 40 feet for a reason. Wires, other antennas, and metal 
buildings. The shop interior is bonded barn metal. and there is a 40 
meter, half wave, sloping dipole that detunes the AV-640 and is detuned 
by the AV-640 when the AV-640 is lower.

Also they say to mount the AV-640 at least 8' above any conductors, 
metal roofs, rain gutters, etc...

The tower the AV-640 is on, is getting moved and will be replaced by a 
25G supporting the TH-5 we just took off the top of the 100' 45G. So, 
where the AV-640 is going to end up, I don't know. I just finished 
reassembling the repaired center section of the boom for the TH-5 and 
should have it all back together tomorrow. Now comes the hard work of 
digging up the base of the one tower and planting the other as well as 
making a new bracket to the shop roof.

73 and thanks for the correction.

Roger (K8RI)