Yes indeed 800 ohms is perfect as a termination. This device seems to be
a real brute and may have come from military surplus as they used T2FD
antennas for many installations because their work was very frequency
agile from 2-30 Mhz. I guess since they had big QRO transmitters the
induced termination loses were not a problem for them. The T2FD is said
also to be a fairly quiet antenna.
On 1/25/2017 12:45 PM, Perry Ogletree K4PWO wrote:
It may be intended for a terminated antenna design like a T2FD or terminated
sloping wire. In those designs, you have a folded dipole with a termination
resistor joining the ends for the T2FD or an end fed wire with a termination
resistor at the far end to ground.
The ratio may be 16:1 as they are usually multiples of 2 for a 800 ohm
termination. Check that with an antenna analyzer and see if it measures the
same as the 1K ohm did.
Perry K4PWO
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Herbert Schoenbohm
Sent: Wednesday, January 25, 2017 9:26 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Strange Balun...please help
I came into the possession of two unusual high power baluns, one with 125'
of RG-213 attached and the other with a two foot lead of coax attached.
They are seal and inside PVC with the coax going inside the bottom and large
eyelets for the wire and support in the center. They appear to be
commercially made. I soon found tat they are not current baluns judging
from the discovery that there is no DC continuity to either wire connection
from the coax. With a bridge and a 50 ohm non-inductive resistor the VSWR
is very high. However when I put a 1000 ohm resistor on the antenna
connections the balun is flat from 1.8 to past 60 Mhz. This would make the
device a 20:1 balun which is something I have never heard of. What kind of
antenna requires such a high impedance feed? If anyone has any knowledge of
the use for these devices please let me know. Thanks
Herb, KV4FZ
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