[TenTec] Antenna Tuner 238

[Bob McGraw - K4TAX]

Tony:

Further to my earlier comments.  First, I suggest doing a simple DC 
resistance check across the traps.  One or both may have failed, more likely 
in making connection between the 40M and the 80M section thus providing what 
looks like an open circuit or very short antenna to the tuner on 75M.  A 
close inspection of the connections should show any problems.

Since you indicated no problems on 40M and 20M then we should presume, using 
a coax feedline, the connections at the feed point are good.  If SWR, with 
the tuner in bypass position, is less than 2:1 then we can assume the coax 
and feed connections are good.

These traps are basically a type of resistance wire that has a resonant 
frequency that is quite broad.  However, due to the Q of the traps, the 
antenna will have a low SWR on 75M only across about 60 to 70 kHz. {Comment: 
putting resistance in an antenna is somewhat like using a dummy load 
although it looks like a broadband antenna to the transmitter.}

Also the DX-CC antenna has a gas discharge tube at the feed point.  That 
point on 75M will be somewhat of a high voltage point and the SEP may fire 
or have failed thus looking like a short to the feedline and tuner.  Perhaps 
you are using a balanced feedline and not coax feed.  The installation 
states that the SEP must be removed if used with a balanced feed for 75M.

73
Bob, K4TAX


----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
To: <tony at ammocomp.com>
Sent: Tuesday, January 22, 2008 6:01 PM
Subject: Re: [TenTec] Antenna Tuner 238


> Tony:
>
> What type problem are you having?  With the tuner in bypass mode, what 
> does the SWR direct to the antenna look like?  Also, what does the SWR 
> look like on 40M and 20M when the tuner is in bypass mode.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- 
> From: "Tony Dangelo" <tony at ammocomp.com>
> To: <tentec at contesting.com>
> Sent: Tuesday, January 22, 2008 4:26 PM
> Subject: [TenTec] Antenna Tuner 238
>
>
>> Hello to all,
>>
>> I am having a hard time with the 238 tuner and an alpha delta DX
>> CC antenna while trying to tune on 75 meters only.  I have no problems
>> with the tuner on 40 meters and or 20 meters I suspect the traps are the
>> culprits which are causing some discomfort for the 238.
>>
>> Am I missing something?
>>
>> 73,
>>
>> Tony - KB1PSX
>>
>>
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>