[TenTec] 160 meters, ten ted 238 tuner, part two

[Bob McGraw - K4TAX]

I normally use a home brew balanced tuner that I built for my balanced wire 
antennas.

In order the check my sanity on the topic, I switched my 160M antenna, being 
some 256 ft of #12 wire being center fed with balanced feed.  The antenna is 
configured as somewhat of an inverted V with the center at 50 ft and the 
ends at about 25 ft.  The balanced feedline is connected direct to the 
balanced output of the Tentec 238 tuner with the required jumper in place on 
the rear.  Thus I am using the internal balun of the 238 tuner.

To tune across the entire 160M band and attain a 1.2:1 or better SWR does 
require connection of a 500pf capacitor to the External Capacitor terminal 
to ground.  Your installation may require a 1000pf as originally supplied. 
At the low end of the band {1.800 MHz} the switch is at #5 on the High Z 
position.  To tune the upper end of the band {2.000 MHz} the switch is at #3 
on the High Z position.  I checked 4 additional frequencies and found there 
was no issue in attaining a 1:1 match at any of the points checked.   At 
1.900 MHz the switch is on #4 position and the variable C at about 50%. 
With this configuration the tuning C seems somewhat broad in range with the 
2:1 SWR points being some 40 KHz above and below the center frequency.  I 
noted very little change in inductance value is required to tune the entire 
band.  Inductance value is about 60% of maximum.

I did note that the SWR indication on the OMNI VII did show about a 1.3:1 
indication while the indication on the Antenna Analyzer shows a 1.1:1 match. 
At the same time an external SWR bridge shows anywhere between a 1.1:1 to a 
1.3:1 match.  It seems at this point between the 3 instruments or 
measurement means, I'm splitting hairs so to speak.

Don't know if this will shed any light on the topic but it sure seems like 
the suspect system should work with the 238 tuner and internal balun.

73
Bob, K4TAX







----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Thursday, October 31, 2013 12:17 PM
Subject: Re: [TenTec] 160 meters, ten ted 238 tuner, part two


> Having gone back and reviewed some 30 or so e-mail exchanges on this 
> topic, it is my conclusion that the length of the wire should be OK and 
> the type and length of the feed-line should be OK.    Further, this 
> configuration should be relatively easy for most all external tuners to 
> affect a good match, all bands, from 160M - 10M.  There is something yet 
> to be discovered in, with, or related to the installation that is the 
> cause of this issue.
>
> The fact that the 253 Automatic tuner finds a match, somewhat affirms that 
> the wire length. antenna position and the feed-line type/length is not the 
> issue.
>
> 73
> Bob, K4TAX
>
>
>
> ----- Original Message ----- 
> From: "Mike Bryce" <prosolar at sssnet.com>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Wednesday, October 30, 2013 2:11 PM
> Subject: [TenTec] 160 meters, ten ted 238 tuner, part two
>
>
> Well gang,
>
> It’s great being able to move again and once more I’m in the shack.
>
> I did some interesting testing with my doublet.
>
> here’s a recap
>
> 132 feet on each side fed with 180 ish feet of 600 ohm open line. That 
> goes to an external 1:1 balun feed with three feet of LMR400 to the 
> coupler.
>
> A palstar coupler and the Ten Tec 238 coupler were unable to find a match.
>
> So I added 15 feet to both ends.
>
> No joy.
>
> I added about 10 feet of wire inside the shack and strung it across the 
> ceiling. Looks like hell, but it’s up there
>
> The palstar will find a solution at 1.890 now, but the swr is around 2.7:1
>
> The 238, not so much. I did get it to tune, but the SWR slowly increased 
> (I plan on modifying the coupler with the high voltage doorknob caps)
>
> Now, here’s the odd part.
>
> I have a Ten Tec 253 AUTOMATIC tuner. That tuner found a solution for the 
> 160 meter band from one end to the other.
>
> Happy days!
>
> But, using the same tuner, it can’t find a solution on 30 meters.
>
> But the 238 and the palstar will tune it flat.
>
> I don’t mind changing antennas, but swapping out couplers to operate from 
> one band to the other kinda sucks.
>
>
> Mike WB8VGE
>
>
>
> Knowledge is knowing a tomato is a fruit; Wisdom is not putting it in a 
> fruit salad.
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