Thanks for the suggestion Carl.
The original diodes are 1N4148 as indicated on the schematic. Since these were
so plentiful in my spares I replaced the pair of diodes in the 229A circuit
before my original posting. Unfortunately that wasn't the problem
73,
Rick
VE7TK
Website: http://www.ve7tk.com
>________________________________
> From: Carl Moreschi <n4py2@earthlink.net>
>To: Rick W <ve7tk@yahoo.ca>; Discussion of Ten-Tec Equipment
><tentec@contesting.com>
>Sent: Sunday, July 1, 2012 10:04:09 AM
>Subject: Re: [TenTec] 229A SWR Circuit - UPDATE
>
>Also, I believe most diodes in watt meters are germanium. If they ever
>failed and were replaced with silicon diodes, that can mess up
>calibration badly.
>
>Carl Moreschi N4PY
>121 Little Bell Dr.
>Hays, NC 28635
>www.n4py.com
>
>On 7/1/2012 12:44 PM, Rick W wrote:
>> I hung my DVM off the 200uA meter plug and it is completely within specs.
>> Fully adjustable and it seems to be working. So it looks like the Korean
>> made 229A meter has failed.
>>
>> I'll have to do some thinking on a replacement.
>>
>> Thanks for the bandwidth.
>>
>>
>> 73,
>> Rick
>> VE7TK
>>
>>
>> Website: http://www.ve7tk.com
>>
>>
>>> ________________________________
>>> From: Rick W<ve7tk@yahoo.ca>
>>> To: Ten-Tec Reflector<tentec@contesting.com>
>>> Sent: Sunday, July 1, 2012 8:39:29 AM
>>> Subject: 229A SWR Circuit
>>>
>>>
>>> I have recently acquired a 229A tuner. It needed a few repairs - mainly
>>> mechanical - but otherwise seems in good shape. I've replaced the dial
>>> elastic cord and it tunes smoothly and consistently.
>>>
>>>
>>> I am having a problem with the SWR / Power measurement circuitry. I can't
>>> get the meter to full scale and power measurements are way off.
>>> Calibration is impossible.
>>>
>>>
>>> The meter is moving - albeit nowhere near the correct deflection.
>>>
>>>
>>> My guess is that the SWR circuit in the 229A is similar to the current
>>> 238. Is there any history of problems with this circuit. Any reports of:
>>> 1. meter movement failure;
>>> 2. leaky capacitors; or
>>> 3. open or out of tolerence resistors?
>>> This is a pretty simple circuit and virtually all the parts (less the
>>>meter) are likely in my junk box. If there's a history of a part failure I'd
>>>like to start there.
>>>
>>>
>>> Thanks.
>>>
>>>
>>> 73,
>>> Rick
>>> VE7TK
>>>
>>>
>>> Website: http://www.ve7tk.com
>>>
>>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
>
>
>
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