Paul Playford wrote:
> Yup. But figuring out the 1/4 wave, or odd multiple, frequency, is the
> trick. Oh, by the way, we have a short piece of 50 ohm coax on both ends of
> the 75 ohm hard line, plus a balun at the antenna end and we are using a
> tri-band antenna.
>
> Been there, done that.
>
> And it is not a wash - it's a real mess.
>
>
Hmmm...We musta had different 75 ohm hard line <:-))
Although I don't have any up at present I've used over a 1000' in the
past. I'd not hesitate to use 3/4", 75 ohm and never bother with
attaching anything other than the rig and antennas at the ends.
I fed my tribander through over 300' of 3/4" so the lower loss was a
gain as far as compared to even good 1/2" (ok 0.407) coax. I had no RFI,
no feedback, and excellent results. I also fed 144 and 440 arrays
through the stuff.
I've never bothered doing anything special with it. I just put it up,
try it, and then use it. Now that I have an analyzer I'd check it with
that, but the math works out to where with much over 100' doing anything
much other than installing it is a waste of effort.
I did use 75 ohm pig tails to the tuner and antennas, rather than 50 ohm.
OTOH I've always found it to be well within the range of the internal
tuners of today's rigs and within the range of the pi-net on the older
tube type rigs.
73
Roger (K8RI)
> Much easier to just stick with constant impedance transmission line.
>
> de Paul, W8AEF
>
> ZF2JI/ZF2TA FO8DX/FO8PLA 8Q7AA XZ0A VU7RG TX5C
>
>
>
>
>> ----- Original Message -----
>> From: "Perry - K4PWO" <k4pwo@comcast.net>
>> To: "Paul Playford" <paul@w8aef.com>; <towertalk@contesting.com>
>> Sent: Monday, April 20, 2009 1:45 PM
>> Subject: Re: [TowerTalk] Hardline ?
>>
>>
>>
>>> Only if its a 1/4 wave, or odd multiple, long... Otherwise, it'll just
>>> give
>>> you a 1.5:1 VSWR "IF" your antenna is a true 50 ohm match. Since it has
>>> lower loss than 50 ohm coax, its usually a wash on station impact.
>>>
>>> 73 de Perry - K4PWO
>>>
>>>
>
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