[TenTec] Request for Assistance

Bob McGraw K4TAX rmcgraw at blomand.net
Thu Oct 22 22:15:19 EDT 2020 

Tnx. 

Bob, K4TAX


Sent from my iPhone

>> On Oct 22, 2020, at 8:01 PM, Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
> I hope it gets posted to the site. I was notified it was held due to too many recipients.  
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>>> On Oct 22, 2020, at 7:51 PM, Matt Harper <mharper2240 at gmail.com> wrote:
>> 
>> Excellent.  Thank you Bob.  Much appreciated!
>> 
>> I hope our paths cross again.
>> 
>> All the best,
>> 
>> Matt, K4KIU 
>> 
>>> On Thu, Oct 22, 2020 at 8:45 PM Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
>>> I’ve posted to the Tentec group.  Factually, this is a small issue to resolve.  I’ve applied my repair approach to AM broadcast transmitters as far back as 1960.   
>>> 
>>> The biggest issue is to figure out what caused the flash over and determine how to prevent this from occurring again.   I also touched on that in my earlier response. 
>>> 
>>> Bob, K4TAX
>>> 
>>> 
>>> Sent from my iPhone
>>> 
>>>>> On Oct 22, 2020, at 5:02 PM, Matt Harper <mharper2240 at gmail.com> wrote:
>>>> 
>>> 
>>>> Hi Bob,
>>>> 
>>>> Very helpful.  Thank you. 
>>>> 
>>>> It's helpful that you've had good success with the repair process that you described.  Have you had any further communications with David on this topic?  That would be good to know since I'll be talking with David on Tuesday for our regular sked,  If you'd like to join us, you're very welcome to do that.  
>>>> 
>>>> 73's and thanks again for sharing your knowledge on this topic.  For the record, I have a Ten-Tec Orion II and really like it. No problems with the Orion whatsoever!
>>>> 
>>>> Matt, K4KIU  
>>>> 
>>>> Matt Harper
>>>> (804) 399-3422
>>>> mharper2240 at gmail.com
>>>> 
>>>> 
>>>>> On Thu, Oct 22, 2020 at 5:39 PM Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
>>>>> Matt et al:
>>>>> 
>>>>> I doubt that Tentec would have a direct replacement.   You might send an e-mail to SERVICE at Tentec.Com and ask for availability and price.  
>>>>> 
>>>>> From my take, the capacitor arced over thus resulting in burning one or two plates.  From experience, they can be repaired using the method I earlier outlined.   I've done it successfully several times.   On my Centurion and other amps that use air dielectric variables. 
>>>>> 
>>>>> As to replacing it with an new one, there is no assurance that the same thing won't occur with a new one.   After all, what caused it to happen in the first place?   These things don't wear out.   However, if they flash over, damage occurs and this damage can be repaired. 
>>>>> 
>>>>> Just my take and experience on the issue. 
>>>>> 
>>>>> 73
>>>>> 
>>>>> Bob, K4TAX
>>>>> 
>>>>> 
>>>>> 
>>>>> On 10/22/2020 12:15 PM, Matt Harper wrote:
>>>>>> Hi Jerry,
>>>>>> 
>>>>>> Thank you for your research, message and overall help!  All much appreciated (along with the manual for the amplifier).  After a number of years of good service,  it would seem like replacing the capacitor would be the best solution, if possible.  However, Bob’s excellent suggested approach to repairing the current one may be the best and/or only way to go.
>>>>>> 
>>>>>> Thanks again!
>>>>>> 
>>>>>> Matt, K4KIU 
>>>>>> 
>>>>>> On Thu, Oct 22, 2020 at 12:11 PM <ni4f at earthlink.net> wrote:
>>>>>>> Hi Matt.  David posted a message to the Ten-tec reflector on 15 October posing the question to the reflector:
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> > Good morning all,
>>>>>>> 
>>>>>>> > > I have an excellent condition Centurion that I purchased in 2015 from a
>>>>>>> 
>>>>>>> > Ham
>>>>>>> 
>>>>>>> > > in Marietta GA
>>>>>>> 
>>>>>>> > > ( NK9R) and he purchased it in 2001 from another ham and then sent it
>>>>>>> 
>>>>>>> > into
>>>>>>> 
>>>>>>> > > Ten-Tec for a QSK installation and a new fan.
>>>>>>> 
>>>>>>> > > The 422 has been working faultlessly for years until last week. I got a
>>>>>>> 
>>>>>>> > > buzzing sound of 20m. So I stopped using it. I got a similar buzzing
>>>>>>> 
>>>>>>> > sound
>>>>>>> 
>>>>>>> > > at 40m.
>>>>>>> 
>>>>>>> > > Nothing has changed, all grounding and bonding in place( I'm in Ecuador
>>>>>>> 
>>>>>>> > and
>>>>>>> 
>>>>>>> > > have been operating with the same coax, 4" copper flashing for a ground
>>>>>>> 
>>>>>>> > and
>>>>>>> 
>>>>>>> > > bonding)
>>>>>>> 
>>>>>>> > > I opened up the cover and found on the stationary plates and the rotor
>>>>>>> 
>>>>>>> > > plates small pitting and some small melting.
>>>>>>> 
>>>>>>> > > *What would cause this?*
>>>>>>> 
>>>>>>> > >
>>>>>>> 
>>>>>>> > > *I'm looking for an option on cleaning the plates. Can/should this be
>>>>>>> 
>>>>>>> > > done?( short term)*
>>>>>>> 
>>>>>>> > > *(Long term)Where can I purchase a Tuning Air Capacitor to replace this
>>>>>>> 
>>>>>>> > > one? I was trying to find the uf and voltage rating, but I can't seem to
>>>>>>> 
>>>>>>> > > find it in the manual? Looking in the wrong schematic.*
>>>>>>> 
>>>>>>> > > Any help would be appreciated.
>>>>>>> 
>>>>>>> > > Thx
>>>>>>> 
>>>>>>> > > *David-*
>>>>>>> 
>>>>>>> > > *HC5DX*
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> FIRST RESPONSE WAS FROM A TEN-TEC GERU K4KAX THE SAME DAY
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> > David:
>>>>>>> 
>>>>>>> > 
>>>>>>> 
>>>>>>> > The buzz is the result of arcing between the plates of the capacitor.
>>>>>>> 
>>>>>>> > This typically is the result of the amplifier being too lightly loaded
>>>>>>> 
>>>>>>> > resulting in excessive RF voltage in the output network.   Or perhaps
>>>>>>> 
>>>>>>> > the SWR is high.   In either case, the voltage in the PA tank was
>>>>>>> 
>>>>>>> > excessively high resulting in the arc.   Grounding has nothing to do
>>>>>>> 
>>>>>>> > with the issue but all equipment should be bonded to a common point for
>>>>>>> 
>>>>>>> > safety reasons.
>>>>>>> 
>>>>>>> > 
>>>>>>> 
>>>>>>> > You can remove the capacitor and disassemble it.  Then using a file,
>>>>>>> 
>>>>>>> > carefully file away the rough areas of the affected plates. Then finish
>>>>>>> 
>>>>>>> > smoothing them with fine steel wool.   The plates are very soft and can
>>>>>>> 
>>>>>>> > be damaged by excessive force.  I suggest laying each plate on a flat
>>>>>>> 
>>>>>>> > surface when you are working on it, applying a downward force.  Then
>>>>>>> 
>>>>>>> > reassemble and install the capacitor.
>>>>>>> 
>>>>>>> > 
>>>>>>> 
>>>>>>> > I suggest you check your SWR on your antenna system.  Any value of 3:1
>>>>>>> 
>>>>>>> > or greater is not suitable for the amplifier.  Address and correct the
>>>>>>> 
>>>>>>> > antenna system.    Also when tuning the amplifier be sure to TUNE and
>>>>>>> 
>>>>>>> > LOAD the amplifier correctly always adjusting for maximum output.  Then
>>>>>>> 
>>>>>>> > reduce drive to the desired operating power, but DO NOT change any
>>>>>>> 
>>>>>>> > tuning or loading.
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> THEN DAVID POSED ANOTHER MESSAGE AS FOLLOWS
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> Hola Bob,
>>>>>>> 
>>>>>>> Thx for the comeback and suggestions.
>>>>>>> 
>>>>>>> SWR is 1.3.1
>>>>>>> 
>>>>>>> I found this on RF Parts, do you think if will work?
>>>>>>> 
>>>>>>> https://www.rfparts.com/73-1100-49.html
>>>>>>> 
>>>>>>> *David-*
>>>>>>> 
>>>>>>> *HC5DX*
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> DON’T KNOW IF BOB ANSWERED HIM OFF LINE OR NOT.  I HAVE COPIED BOB K4TAX ON THIS EMAIL
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> 73, JERRY NI4F
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> From: Matt Harper <mharper2240 at gmail.com> 
>>>>>>> Sent: Thursday, October 22, 2020 11:04 AM
>>>>>>> To: ni4f at earthlink.net
>>>>>>> Cc: Barry Gold <n9bs at embarqmail.com>; Bobr1919 at hotmail.com; Calvin <k1cal at bellsouth.net>; K8kas1 at aol.com; bernsteinmarty at gmail.com; robertriley4180 at att.net; voila1 at optonline.net; w3frg1 at gmail.com; w4vr at verizon.net; wc1t at arrl.net; wf8i at hotmail.com
>>>>>>> Subject: Request for Assistance
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> Good Morning All,
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> My friend David, HC5DX near Cuenca, Ecuador is having a problem with his Ten-Tec Centurion amplifier.  Here are the specifics from him that I copied from another email.  This was from a noted he sent to Palstar.
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> “My Ten-Tec Centurion Amplifier arced the other day on three Stator plates and 4 rotor plates.
>>>>>>> 
>>>>>>> Do you sell the plates( if not would you know where I can purchase them?) or would you sell the entire capacitor?”
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> Palstar either hasn’t replied or they can’t help him.  
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> Do any of you know where he can get an exact replacement for this capacitor?  After several COVID-related failed attempts to visit him, I have a trip planned to Cuenca on November 11.  It too may get delayed, but it’s still on as of now.  If I go then, I could take ithe part with me.
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> Any ideas you have would be appreciated!
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> Thanks and 73’s,
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> Matt,  K4KIU 
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>>   
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>>  
>>>>>>> 
>>>>>>> --
>>>>>>> 
>>>>>>> Matt Harper
>>>>>>> (804) 399-3422
>>>>>>> mharper2240 at gmail.com
>>>>>>> 
>>>>>> -- 
>>>>>> Matt Harper
>>>>>> (804) 399-3422
>>>>>> mharper2240 at gmail.com
>> -- 
>> Matt Harper
>> (804) 399-3422
>> mharper2240 at gmail.com

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