"Richard Clark" wrote in message
...
On Sun, 18 Jan 2009 00:52:28 -0800 (PST), JIMMIE
wrote:

Googling TV BalUn was useless but searching fot 2M Balun proved more
useful. Per an article by K3MT they should be able to handle power in
the 5 to 10 watt range. More than enough for my purpose. I cracked
open a couple and foundd that tthe type that go frm screw connectors
to male F connector have a larger transformer than the barrel type.
This was at least true for the couple that I sacrificed to the radio
gods.
K3MT"s data was on the barrrel or tubular type.

Jimmie

Hi Jimmie,

So, going further with this resource you found, was there any report
of how "well" it worked? Merely surviving the application of 5 to 10
Watts isn't exactly proof of suitability for performance. Even a SWR
report could mask the fact that a BalUn inappropriately applied is
operating as a padding resistor.

Going further yet, was it reported what style of BalUn it was?
Guanella? Ruthroff? Not all BalUns perform equally, and for
reception (the class of BalUn you are mining for transmission
application) it is arguable that it matters.

Lastly to your first statement
Googling TV BalUn was useless but searching fot 2M Balun proved more
useful.
The distinction was useful, but were you Googling the Web, or this
group?

73's
Richard Clark, KB7QHC

Hi Richard

I made some insertion loss measurements on some of the low cost TV (4:1)
baluns when I was trying to understand that 137 MHz antenna. I didnt save
any data. I did use several types of baluns. They were all typically the
Radio Shack quality. At 137 MHz, the insertion loss was about 2.5 dB for
two baluns connected in series, back to back. I know that seems high, but
the units are really not well built.
It seems that the original poster, Jimmie, might consider using RFI
ferrites around the coax instead of the TV 4:1 baluns. My measured data
indicates the low cost ferrites, intended to be used to minimize RFI
conduction on the outside of cables, work quite well at 144 MHz.

Jerry