[TenTec] Model 238C Tuner Questions

[Bob McGraw - K4TAX]

I sure agree with Steve on this one.  All of my baluns are 1:1 current 
baluns and most are rated at 5KW even though I only run 1200 watts or so.  I 
do not use the internal balun in the 238 series of tuners.  Same for a 
couple of other non Tentec tuners rated for "legal limit" power.

Yes adjusting the feedline length will do marvels for making the matching 
easy on all bands with one antenna.  In many cases, adding or removing 3 to 
5 ft of feedline is all that's needed to make things work very nicely.

73
Bob, K4TAX


----- Original Message ----- 
From: "Steve Hunt" <steve at karinya.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Tuesday, October 16, 2012 3:27 PM
Subject: Re: [TenTec] Model 238C Tuner Questions


> It might or might not be a high impedance load for the tuner, depending on 
> the length of the ladderline. For example, an 80m half-wave dipole used on 
> 40m will have a feedpoint impedance of 4000 Ohms or so; feed that through 
> an electrical quarter-wave (or odd multiple) of ladderline, and the tuner 
> will see a load of about 40 Ohms. With careful choice of feedline length 
> you can usually avoid impedances that are either outside its matching 
> range, produce high losses, or create excessively high voltages.
>
> After some tests on losses and current balance, I now feed my 
> doublet/ladderline combination from my 238 tuner using an external 1:1 
> current balun rather than the internal 4:1 voltage balun.
>
> Steve G3TXQ
>
>
>
>
>
>
> On 16/10/2012 20:56, Rick - DJ0IP / NJ0IP wrote:
>> Bob,
>>
>> I agree with you but let me play devil's advocate...
>>
>> There are those who say a center-fed dipole, say for 80m, fed with 
>> openwire,
>> with have a high impedance on its even harmonic - a couple thousand Ohms.
>> Doesn't this result in excessive power loss in the matchbox?
>>
>
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