OCFD: Mounting and the Mast (#864)

Rick, W3AMT, Has a question on where to put his balun antenna on his shed. He moved his ham shack to the sheld. Watch to learn more about how to calculate and place his balun.

Edited and Videographed by Aidan Jakeman

Twitter: @dcasler

[jasmuz]

Thanks Dave for your continued effort to instruct Amateur Radio Operators all around the globe! 73's from HI8MSB

[subramanianr]

Hi Dave, the question is very clear.
He is going to have an EFHWA using a core of around 3" in diameter and a 20KV 100pF capacitor. His term (or Google 's term) union means the UnUn. Or his pronunciation of the term UnUn must have been mis-spelled as union, who knows. He must clarify.
He wants to know if the metal roof of the shed (his new shack) would affect the performance of the new antenna. The mounting pole (30') is a strong water pipe.
He never asked for a plumbing solution.
Yes, we don't do plumbing job here (except when we talk about the "plumber 's delight antennas" for the VHF UHF bands using the 10 mm copper pipe like the J pole, copper cactus or the slim Jim)
The 1:49 transformer (UnUn) is NOT an auto- transformer. It's a regular step-up transformer of with one end (cold) of the two windings connected together to be grounded (ie, to the shield braid of the coaxial cable)
The turns ratio can be 2:14 or 3:21 for the 1:49 impedance transformation.
If one is interested in the low frequency bands he can go for higher turns ratio.
Yes, coming to his important question as to whether the metal roof would affect the performance of the EFHWA, No, it will be working fine if the half lambda radiator wire is installed away from the metal roof. (that's what he has proposed, I believe)
If he is using some counterpoise or some grounding options the metal mast (as you suggested) or the metal roof itself can be experimented.
De VU2RZA