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
>
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|