The extra / external cap is used across the capacitor bank, starting at
position #4 and #5. Both on the Low and High Z sides. I find the text is
incorrect, the schematic is correct. Yes a .01 is way too much C by a
factor of 10x.
If you have a means to do so, what is the natural resonant frequency of the
antenna? I use my MFJ-259 as a grid dip meter effect to find the resonant
frequency. I'm not speaking of some frequency where the SWR is 1:1 or such.
I take a different approach to antennas. I first start with a resonant
antenna at the desired frequency, then adjust the height of the antenna to
attain the desired feed point impedance. I saw Jim Brown, K9YC mentioned
this in his earlier post as he used different coax impedance lines dependant
on the height of the antenna. I am not one to "prune" the length of the
antenna for some SWR value. Now in cases I know we can't get the antenna at
different heights specially as we get to 160M and to some extent 80M. In
these cases, the typical height above ground does bring the center Z to 20
to 30 ohms. Nothing wrong with this. With low loss coax or a balanced
feed, just let the tuner deal with it. That's what it is supposed to do. I
find having a resonant wire is more effective and easier to effect a good
match.
73
Bob, K4TAX
----- Original Message -----
From: "Mike Bryce" <prosolar@sssnet.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, October 12, 2013 9:17 AM
Subject: Re: [TenTec] Antenna is up, but the coupler doesn't like 160 meters
bob and the group
I didn't have the .001 in a voltage rating that would live so I used a
.01, and yeah, I know that's way too much C
for the instructions, it looks like the extra c is only used in position 5
on the low z side of the switch.
Now, all that being said, NONE of the antenna couplers will find a
solution to the tuning of the band
the best I can get is around 1.995 and it's high there about 2:1 or so
of course everything is grounded.
I'm going to drop the wire down and measure it from the center to the ends
and see what I have.
I did some looking around the 'net last night and read that adding a 1/8
wavelength should correct the problem, however, that's 33' of open wire
and simply not doable. What in the world do you do with it?
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
o|||||||o
A man with one clock knows what time it is. A man with two clocks is never
sure.
On Oct 12, 2013, at 8:47 AM, Bob McGraw - K4TAX wrote:
Are you using any extra C connected to the rear terminals of the tuner?
Likely needed if the high Z switch is in #5 position. The extra C is
1000 pf @ 500 V as provided by Tentec.
I use 256 ft of wire {natural resonance measured to be 1.85 MHz}, center
fed with 450 ohm window line, about 65 ft, connected direct to the center
feed point of the antenna and direct to the 1:1 W2FMY current balun at
the operating position. The balun is connected to the Tentec 238 tuner
via about 1 ft of RG-213. To get to the low end of 160M I do have to
connect the extra C to the rear terminal of the tuner.
This arrangement will work all bands, all frequencies 160M - 10M,
attaining a 1.5:1 match or better. Center of the antenna is at 50 ft
configured as an inverted V with the ends about 25 ft above the ground.
73
Bob, K4TAX
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