[TowerTalk] Fw: Flag Antenna Transformer

[Gene Fuller]

----- Original Message ----- 
From: "Gene Fuller" <w2lu at rochester.rr.com>
To: "Al Kozakiewicz" <akozak at hourglass.com>
Sent: Thursday, February 02, 2012 10:19 AM
Subject: Re: [TowerTalk] Flag Antenna Transformer


> Al -My guess is that it was just being completely over powered, not due to 
> a mismatch. Gene / W2LU
> ----- Original Message ----- 
> From: "Al Kozakiewicz" <akozak at hourglass.com>
> To: "Gene Fuller" <w2lu at rochester.rr.com>; "Pete Smith N4ZR" 
> <n4zr at contesting.com>; <towertalk at contesting.com>
> Sent: Thursday, February 02, 2012 10:09 AM
> Subject: RE: [TowerTalk] Flag Antenna Transformer
>
>
> I constructed a K9AY initially using a Minicircuits device for the 
> transformer.  I can state unequivocally that they are very delicate.  My 
> K9AY is 100 feet away from a Butternut vertical.  Tuning the AL-1500 up on 
> 40m creates enough induced power to reliably blow that transformer every 
> time.
>
> Al
> AB2ZY
>
> ________________________________________
> From: towertalk-bounces at contesting.com [towertalk-bounces at contesting.com] 
> On Behalf Of Gene Fuller [w2lu at rochester.rr.com]
> Sent: Thursday, February 02, 2012 10:06 AM
> To: Pete Smith N4ZR; towertalk at contesting.com
> Subject: Re: [TowerTalk] Flag Antenna Transformer
>
> Keep  in mind that on 75/80 meters a pennant, flag, or ewe will only have 
> a
> "gain" of around -20dbi. so another db or two of loss due to miss match
> will hardly be noticed and certainly isn't going to result in result in
> damage due to heat or rf burns - or am I missing something ? However, if
> you're running a "phased" pair with transformer "matching" you would want 
> to
> keep track of the phasing.
> Gene / W2LU
>
> ----- Original Message -----
> From: "Pete Smith N4ZR" <n4zr at contesting.com>
> To: <towertalk at contesting.com>
> Sent: Thursday, February 02, 2012 6:30 AM
> Subject: Re: [TowerTalk] Flag Antenna Transformer
>
>
>> Is this necessarily true?  I have a couple of transformers built by
>> ON4UN.  They use separate windings and a binocular core, and behave
>> exactly as expected.
>>
>> 73, Pete N4ZR
>> The World Contest Station Database, updated daily at
>> www.conteststations.com
>> The Reverse Beacon Network at http://reversebeacon.net, blog at
>> reversebeacon.blogspot.com,
>> spots at telnet.reversebeacon.net, port 7000 and
>> arcluster.reversebeacon.net, port 7000
>>
>>
>> On 2/1/2012 4:58 PM, Doug Ronald wrote:
>>> You are getting these results because you wound a conventional
>>> transformer
>>> where a Transmission Line Transformer (TLT) is required. The core is
>>> fine,
>>> but twist the primary with the secondary using 12 turns and 3 turns. 
>>> Here
>>> is
>>> a reference to some theory on what you need:
>>>
>>> http://home.earthlink.net/~christrask/TraskTLTTutorial.pdf
>>>
>>> and the author (Chris Trask) has several other TLT articles on his web
>>> site
>>> including precise winding tips.
>>>
>>> Here is another helpful link to the way your finished transformer should
>>> look:
>>>
>>> http://www.qsl.net/wa1ion/bev/bb_antenna_matching.pdf
>>>
>>> Hope that helps,
>>>
>>> -Doug, AE6SY
>>>
>>>
>>>
>>>> I have a flag antenna which has worked well for several years. I used a
>>> Minicircuits T16-6 transformer to couple the ~800 ohm termination
>>> resistance
>>> of the antenna to 50 ohm line. Recently I decided to do some upgrades, 
>>> so
>>> I
>>> followed the recommendations of many (here and elsewhere) and made a
>>> matching transformer using an FT-140-43 core and 34:8 turns, secondary
>>> and
>>> primary on opposite sides of the core. I didn't have any #28 wire so I
>>> used
>>> #24. I tested this with a miniVNA, terminating the antenna side with an
>>> 800
>>> ohm noninductive resistor. The impedance does not look right at all;
>>> there
>>> is a lot of inductive reactance and the resistive part starts at 125 
>>> ohms
>>> and climbs steeply from 1.7 MHz. No on-the-air results yet.
>>>
>>>
>>>
>>> I'm wondering if this is right or not - measurements indicate the DIY
>>> transformer is much worse than the T16-6 in terms of presenting a good
>>> match.
>>>
>>>
>>>
>>> This would not be the first case of theory saying it won't work but
>>> practice
>>> says it will - just looking for a reality check here. Seems to me like
>>> the
>>> core material is all wrong...
>>>
>>>
>>>
>>> -Tony, K1KP
>>>
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
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>>>
>>>
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