[TenTec] 238B Tuner problems

[Bill Miner]

Natan and All,

The small wheel on the roller inductor comes from Ten-Tec with some black 
conductive lubricant.  If you do not replace the lubricant after cleaning 
you may experience problems from wear later on.

F Y I  even though I have been licensed just as long and love boat anchor 
equipment I do NOT use a pencil to check for RF and have not done so since I 
last had on old ARC-5 transmitter on the air.  Safety First!

73,  Bill
----- Original Message ----- 
From: "Natan Huffman" <W6XR at Frontiernet.net>
To: "'Discussion of Ten-Tec Equipment'" <tentec at contesting.com>
Sent: Wednesday, July 14, 2010 4:38 PM
Subject: [TenTec] 238B Tuner problems


> Dear Friends,
>
> Today, I resolved a problem encountered with my Ten Tec 238B antenna 
> tuner.
> A week ago, my 238 started to misbehave and presented with what appeared 
> as
> an "open" in the tuner.  No discernable flash over had taken place as the
> problem appeared spontaneously without any noise, smell or any indication
> trouble was brewing.  The VSWR meter stopped working and no RF was getting
> through to my Array Solutions Power Master residing after the tuner in the
> RF chain.
>
> This morning a telephone call to John at mother Ten Tec ended up with
> instructions to send it home to be subjected to proper trouble shooting,
> however, to do that would involve being off the air for longer than what I
> wanted to be.  Therefore one last attempt to ascertain the problem and at
> Ten Tec Johns suggestion, I inspected all the wafers on the switches 
> inside.
> All the tabs were there and none showed wear at all.  Finally, I became
> suspicious of just where the RF was going because using my #2 lead pencil 
> I
> could see it certainly was not getting to the output SO239 as it should. 
> It
> was easy to draw a spark up to the roller at the variable inductor but no
> spark at all anywhere on the body of the inductor.  The wire wrapping 
> around
> the inductor body was void of any corrosion or flash indication.
>
> Having nothing to loose, I grabbed the can of contact cleaner and doused
> both the wheel and all the wire on the inductor form.  While still damp, a
> cotton cloth was used to wipe off the excess contact cleaner.  My 
> suspicion
> was confirmed as after the cleaning of the inductor and its little wheel,
> all was well.  It became easy to get a 100 watt spark with the lead pencil
> on the body of the inductor, the VSWR meter started working and the Power
> Master showed RF just the way it should.  A few hours post, the 238 is 
> doing
> everything it used to do prior to becoming symptomatic.
>
> I suppose the moral here is to clean the inductor and its little wheel
> because even if it looks clean, enough crud does form to insulate the 
> wheel
> from the wire on the form.  Perhaps others have found this same problem
> before.  It's very nice to avoid a trip to mother Ten Tec and its 
> associated
> cost and inconvenience.  Using a wooden lead pencil for RF sniffing is 
> only
> allowed if you are into boat anchors and have been licensed over 40 years.
> A mechanical pencil's use can be downright dangerous so only use a wooden
> #2!
>
> 73
>
> Natan W6XR
> Freeville, NY
>
>
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