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Re: [TenTec] Centurion & Tubes

To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Subject: Re: [TenTec] Centurion & Tubes
From: <Rick@dj0ip.de>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 4 Aug 2018 06:34:18 +0200
List-post: <mailto:tentec@contesting.com>
Well I bought my first transistorized amp about 25 years ago (ALS-600).
But I had a problem with it in contests.

When operating CQWW DX contest in late November, portable in the mountains
of Liechtenstein (HB0), with snow, ice and wind, the antenna blowing in the
wind tended to have a wandering SWR, up and down.
This would cause the amp to trigger to FAULT.  PITA when contesting.

So I went back to tube amps, buying 5 more tube amps after that (4 with
3-500z and the Centaur).
No more problems with FAULT.

About two years ago I decided to dump every piece of equipment which I can
no longer comfortably carry!
I bought a used ICOM IC-2KL.

I have interfacing problems with the IC-2KL and my Eagle, because the Eagle,
like all Ten-Tec amps does not have ALC feedback to the amp.
Bad decision by Ten-Tec!

This is only on SSB.  I have to run the Eagle at 25 to 30 watts, otherwise
the FAULT triggers on voice peaks.
Output is about 350 watts.

On CW I use external time-sequence keying and just run the Eagle at 30 to 40
watts.  
Works just fine like that.
I can run 500w all day long!
This is good enuff for my current (retired from contesting) needs.

73,
Rick, DJ0IP
(Nr. Frankfurt, Germany)

-----Original Message-----
From: TenTec <tentec-bounces@contesting.com> On Behalf Of Mcelmer1
Sent: 04 August 2018 06:22
To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Centurion & Tubes

Rick,

Transistor amps were the future at least 10 years ago - good choice on your
part. I and several friends have had excellent performance and service life
with 3-500, 4CX1000A, 572B etc. Yes, occasionally one gets a lemon. A friend
bought a NOS Eimac a few years ago - failed less than 5 days after he
installed it.

Auf Wiedersehen,

Mike
W8TRN
----- Original Message -----
From: <Rick@dj0ip.de>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Sent: Friday, August 03, 2018 21:36
Subject: Re: [TenTec] Centurion & Tubes


>I put my 25 year old NOS into my AL-80A and let it cook for a while, then 
>slowly applied power.
> I slowly ran the output power up until about 400w out.
> It increasingly was showing a light blue inside.
> Then pop, boom, BANG.  Blew the fuse in the house.
>
> I sold the amp, and sold the tube for 20 bucks.
> Now I run a transistorized amp.
>
> 73,
> Rick, DJ0IP
> (Nr. Frankfurt, Germany)
>
> -----Original Message-----
> From: TenTec <tentec-bounces@contesting.com> On Behalf Of Stan Gammons
> Sent: 04 August 2018 04:28
> To: tentec@contesting.com
> Subject: Re: [TenTec] Centurion & Tubes
>
> Hi Bob,
>
> The 3-500 is subject to going gassy.  IF and that's a big if, I put the 
> old Eimac 3-500 in the amp (best I can read the date code on it, it was 
> made in 1979); I'll bring the amp up with a variac.  The variac I have is 
> 110/120 volts, so I'd have to re-wire the amp since it's wired for
> 220 volts.  Yes, when a tube flashes over; it's fireworks for sure!
>
>
> 73
>
> Stan
> KM4HQE
>
> On 08/03/2018 09:08 PM, Bob McGraw K4TAX wrote:
>> A comment on 3-500 type tubes.  These types of tubes have an extremely
>> high vacuum.   NOS units are subject to air leakage into the envelope
>> around the pin seals.  The coated anode in the 3-500Z and 3-500ZG
>> serves as the getter to burn the extraneous air out of the envelope.
>> It is a very incorrect belief of many hams that having the filament on
>> for a few hours will burn the air out. This is not true with this type
>> of tube thus having only the filament on serves no useful purpose.
>> The only correct way to burn the air out is to have the tube
>> operational and with enough voltage and current to cause the anode to
>> show color.   It is this heat and chemical action of the anode coating
>> that removes the extraneous air from the envelope.
>>
>> Other smaller tubes may have a getter that is ignited by external
>> microwave energy.  Once the getter is ignited, it is consumed, and any
>> leakage from that point forward will only deteriorate the tube.
>> Again, having the filament on for some hours does no good in this regard.
>>
>> External anode tubes, such as the 3CXxxx and 4CXxxx types, are
>> different designs and thus running the heater will remove any remnants
>> of air leakage as the getter is part of the cathode coating.
>>
>> If you intend to prepare a 3-500ZG or such, a filament supply, an
>> adjustable bias supply, and an adjustable HV supply, with proper
>> metering for each supply is the correct way to static burn in this
>> type tube.  The values are adjusted such that anode does show color.
>>    Just putting the tube in an amplifier and hitting the switch will
>> most likely produce a flash, bang, pop and the smoke may then exit the
>> box.
>>
>> 73
>>
>> Bob, K4TAX
>>
>>
>> On 8/3/2018 8:30 PM, Stan Gammons wrote:
>>> I think most/all of the 3-500's are made in China now.  One can still
>>> find some Eimac's that may still be good after all these years.  The
>>> near 40 year old one I have may still be good.  Need to put it in my
>>> L-4B some times and see. This is what we get for outsourcing so much
>>> of our manufacturing to China.  I've said for many years that that
>>> was a bad idea. At one time Amperex tubes were made in France.  Don't
>>> know if that's still the case.  I'm thinking no.  Maybe we can talk
>>> CPI/Eimac into making 3-500's here again? Probably not, but might be
>>> worth a try.
>>>
>>> 73
>>>
>>> Stan
>>> KM4HQE
>>>
>>>
>>> On 08/03/2018 08:12 PM, Bob McGraw K4TAX wrote:
>>>> Yes, thanks to the new tariffs we can expect tube prices to go
>>>> through the roof.   Most tubes are made in China and branded under a
>>>> US company.   a.k.a. RF Parts.
>>>>
>>>> Bob, K4TAX
>>>>
>>>>
>>>> Sent from my iPhone
>>>>
>>>>> On Aug 3, 2018, at 5:03 PM, Carter <k8vt@ameritech.net> wrote:
>>>>>
>>>>>> On 8/3/2018 4:45 PM, Greg S via TenTec wrote:
>>>>>> There will be a price increase SOON. RF Parts apparently will no
>>>>>> longer be importing Chinese tubes.
>>>>> Hmmm...bad news, as I thought China was the *only* one making
>>>>> 3-500s. If not China, who else?
>>>>>
>>>>> Carter
>>>>> K8VT
>>>>> _______________________________________________
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>>>>>
>>>>
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