Thanks Bob.
73,
Marsh, KA5M
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Bob McGraw
- K4TAX
Sent: Tuesday, October 15, 2013 5:58 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Antenna is up, but the coupler doesn't like 160 meters
Very good analysis.
73
Bob, K4TAX
----- Original Message -----
From: "Marsh Stewart" <marsh@ka5m.net>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Sent: Tuesday, October 15, 2013 9:33 AM
Subject: Re: [TenTec] Antenna is up, but the coupler doesn't like 160 meters
> Mike,
>
> Modeling your doublet with EZNEC+ ver 5.0.59 and making 3 assumptions:
> 1. The antenna is in a straight line
> 2. Each end slopes down from 50 ft to 10 ft above the ground
> 3. Freq 1.830 MHz
> EZNEC calculates the feedpoint impedance to be 15.44 +j44.89
>
> Using TLW with a load of 15.44 +j44.89 on the antenna end and 170 feet of
> 600-ohm open-wire ladder line, the impedance at the station end would be
> about 45.31 -j764.71 or about 766 ohms at -87 degrees.
>
> Your actual measured impedances will vary from the calculated values due
> to
> unknown variables such as nearby objects, house wiring, etc.
>
> With a 1:1 balun (common mode choke) a high-pass L "antenna tuner" would
> need about 32.75 uH of inductance and about 118.1 pF of capacitance. The
> voltage across the inductor would be 5703 volts, and the voltage across
> the
> capacitor would be 5716 volts.
>
> My Ten-Tec 238C "antenna tuner" has an 18uH inductor and the variable
> capacitor has a voltage rating of 3500 volts. It is advertised to match at
> least an SWR of 10:1 any phase angle. You are asking your "antenna tuner"
> to
> match about a 34:1 SWR at a phase angle of -87 degrees.
>
> Of course your antenna / transmission system CAN be matched to 50 ohms at
> 1.830 MHz, but a commercial "standard antenna tuner" might not do it.
>
> There are others with considerable technical knowledge and years of
> real-world experience that regularly read and respond to posts on this
> reflector. Perhaps they will offer more insight on this interesting
> real-world application.
>
> 73,
> Marsh, KA5M
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Mike
> Bryce
> Sent: Monday, October 14, 2013 5:57 PM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Antenna is up, but the coupler doesn't like 160
> meters
>
> 131 on each side
>
> Mike Bryce, WB8VGE
>
>
>
> On Oct 14, 2013, at 6:54 PM, Marsh Stewart wrote:
>
>> Mike,
>>
>> About how long is each side of the doublet? (You may have already given
> this
>> info in a previous post but I do not have it.)
>>
>> Marsh, KA5M
>>
>> -----Original Message-----
>> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Mike
> Bryce
>> Sent: Monday, October 14, 2013 4:53 PM
>> To: Discussion of Ten-Tec Equipment
>> Subject: Re: [TenTec] Antenna is up, but the coupler doesn't like 160
> meters
>>
>> Jim,
>>
>>
>> The antenna is a doublet up 50 feet inverted vee style.
>>
>> It is feed with about 170 ish feet of 600 ohm open line.
>>
>> None of the couplers can find a tuning solution
>>
>>
>> All other bands work fine
>>
>>
>> Sent from my iPad at Aultman hospital.
>>
>> Mike wb8vge
>>
>>> On Oct 14, 2013, at 11:09 AM, Jim GM <jim.gmforum@gmail.com> wrote:
>>>
>>> Hi Mike, WB8VGE
>>>
>>> Hope your surgery goes well for you.
>>>
>>> I have gone and still going thru issues with my inverted L on 160M like
>>>
>>> your having.
>>>
>>>
>>> How long is your antenna? Is it a dipole or Folded dipole? I did not
>>> see on your post the answers to these questions.
>>>
>>>
>>> How high do you have it?
>>>
>>>
>>> Your going to find or have found that the tuner you have and other
>>> tuners will not work on 160M. They just cannot handle a near 50 ohm
>>> match or less no matter what they claim. All they want is your money.
>>>
>>> So you need to add additional matching out side the shack with coils
>>> and homemade capacitors made from coax cable, thats if you have a
>>> limited junk box like I do.
>>>
>>> Any ways the external matching will aid your tuner in the shack to take
>>> care of the rest.
>>>
>>> It will take some time and it is not a quick fix.
>>>
>>>
>>> --
>>> Jim K9TF
>>> _______________________________________________
>>>
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