[TowerTalk] steppir v. lpda

[Jon Zabel]

How's that TH7 on 17 and 12? K7ZA
----- Original Message ----- 
From: "F.R. Ashley" <gdadx2 at clearwire.net>
To: "Tower and HF antenna construction topics." <towertalk at contesting.com>
Sent: Sunday, January 24, 2010 01:24
Subject: Re: [TowerTalk] steppir v. lpda


>
> Am I going to work something on a SteppIR that I can't work on a LP?  Or a
> TH7?
> Don't think so.
>
> 73 Buddy WB4M
> ----- Original Message ----- 
> From: "Steve, W3AHL" <w3ahl at att.net>
> To: "Tower and HF antenna construction topics." <towertalk at contesting.com>
> Sent: Saturday, January 23, 2010 8:05 PM
> Subject: Re: [TowerTalk] steppir v. lpda
>
>
>> Since the Tennadynes that I've seen have a 50 ohm nominal feed point Z,
>> not
>> 200 ohm, the issue is a little different.
>>
>> Having a balun at the front of the boom isn't a problem if it's
>> constructed
>> correctly.  Using a coil of coax bundled up and flapping in the breeze
>> will
>> eventually lead to failure probably.  A better solution is to use ferrite
>> core balun is mounted in a weatherproof plastic box with its output
>> terminals screwed into the boom / transmission line.
>>
>> Some Tennadyne owners do place the 1:1 balun at the mast plate and claim
>> there is no significant difference in the pattern.
>>
>> What affect the feed line imbalance has in either case hasn't been 
>> evident
>> in the few field measurements I've seen posted.  Whether it is enough to
>> justify constructing a custom balanced feed line back to the mast is
>> doubtful, if a couple of ferrites at the mast are effective.
>>
>> LPDA's that do use a 200-ohm transmission line boom usually have a feed
>> point Z of 95-110 ohms.
>>
>> Steve, W3AHL
>>
>> ----- Original Message ----- 
>> From: "Gene Fuller" <w2lu at rochester.rr.com>
>> To: "Tower and HF antenna construction topics." 
>> <towertalk at contesting.com>
>> Sent: Saturday, January 23, 2010 4:23 PM
>> Subject: Re: [TowerTalk] steppir v. lpda
>>
>>
>>> For the umpteenth time,ehy not make up 200 ohm  line,using 1/4" copper
>>> tubing, on standoffs to keep aay from the boom, placing the balun back 
>>> at
>>> the mast, where it is accessible.
>> ..snip..
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>