[TenTec] Care and Feeding of Centurions

Bob McGraw - K4TAX RMcGraw at Blomand.net
Sun Feb 2 16:10:13 EST 2014

Well from experience, many fans have a "lifetime warranty".  Now from my 
take, when the fan fails that is the end of its life and thus the end of the 
warranty.  Same for "lifetime lubrication" in my thinking.

Why did the fan become noisy?  Likely due to bearing wear, thus due to lack 
of lubrication.  I just finished a SB-220 in which the fan was squalling 
like a Banshee.  Cleaning and a couple of drops of oil will keep it alive 
for a few more years.

>From experience with broadcast transmitters from the '40's to current day 
power amps, proper cleaning and lubrication is the key to keeping things 
running.  For example, loosing cooling is certain death to either of those 
items.  Of course many BC transmitters have air flow sensors and switches 
that will shut things down when the cooling fails.

Interestingly, we hams insist on amps to which the fans make little to no 
noise.  So since these do not usually have airflow sensing, and hopefully 
they are very quiet or we are wearing headphones, how do we know we've lost 
cooling?  Usually when smoke comes out of the box.

ASSUME ???      Don't ever do this!  Break it down to 3 syllables:   3 
letters      1 letter      2 letters   Now what do you have?

Bob, K4TAX

----- Original Message ----- 
From: "Mike Pagel, K9UW" <k9uw at wi-net.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Sunday, February 02, 2014 2:50 PM
Subject: Re: [TenTec] Care and Feeding of Centurions

> QST published an article called "Amplifier Care and Maintenance" in 
> September of 2003 and it is available (as a PDF) to members on their web 
> site.  The article includes a flow chart for diagnosing problems.
> My Centurion is ~1992 vintage and I bought it used.  To date, I've 
> replaced several components.  The tubes were first (after dropping one of 
> them while unpacking the amp the day it arrived!).  The original fan 
> became noisy so it was replaced.  A couple of years ago, operator error 
> resulted in a damaged variable capacitor (Tuning), which I replaced with 
> guidance from Jim Rogers at TenTec.  Jim provided superb support to this 
> appliance operator, and I was able to handle the job without shipping the 
> amp back to TenTec for service.
> For some reason, Bob, I had assumed those fans were not to be lubricated. 
> Guess I'd better get in there.....
> 73, de Mike, K9UW
> Amherst, WI
> -----Original Message----- 
> From: Bob McGraw - K4TAX
> Sent: Sunday, February 02, 2014 2:03 PM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Care and Feeding of Centurions
> First, disconnect the power.   The voltage in this unit will KILL YOU!
> Once a year, remove the case and covers.  Be sure the HV shorting 
> strap/bar
> is in tact and does short the HV supply.  This is when the unit is being
> serviced and out of the case.
> Clean the fan blades, add one drop of 3 IN 1 oil to the shaft bearings.
> Take care not to bend any of the fan blades.    Clean any dust from inside
> the case using one of the "computer type" compressed dusters.  Look for 
> any
> discolored connections, discolored areas on the PC boards and, specially 
> at
> the base of the tube sockets.  If any exists, replacement or repair is
> needed.
> Put everything back in place and do install ALL of the screws.  The amp is
> ready for another year of working DX.
> Proper tuning and loading and proper drive is the key to success for long
> amp and tube life.
> 73
> Bob, K4TAX
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