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Author Topic: Tube Linear - Best Practive  (Read 5198 times)
G0MGX
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« on: October 06, 2012, 08:21:44 AM »

Hi Guys

I've just taken ownership of my first (non-homebrew) linear. It's made by a German company Alpin and details are here:

http://www.alpinamplifier.com/index.php?option=com_content&view=article&id=2&Itemid=9

This amp looks very, very much like the ACOM 1000 to me.....

My question is over best practice on leaving this amp in stand-by mode. Are there any downsides - I'm not thinking power consumption - but more tube life et cetera associated with having this switched on all the time when I am in the shack? Already (quite predictably) I have found I have wanted the amplifier when it's turned off and the 2 mins 30 sec warm up time seems like a week when you are listening to a gap in the DX calls!

I'd appreciate any thoughts on the best way to operate and run an amp like this one.

Thanks!

Mark. G0MGX
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NA0AA
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« Reply #1 on: October 06, 2012, 09:02:38 AM »

Well, speaking generally, if you need it, turn it on.

It's sure not an instant warm up, keeping that in mind, I guess you balance how often you switch it on - If you end up turning it on every time you operate anyway, why not reduce the stress on yourself and just turn it on at the start of your operating session and be ready when you need it.

From what I understand, tube life is considered as filament on time, so yes, technically you are putting hours on your tube any time you have the amp on, driving it or not. 

BTW, given what some of those tubes cost, I can appreciate your concern. 

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KD0UN
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« Reply #2 on: October 06, 2012, 09:08:14 AM »

That review is written in some kind of foreign language.
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W8JI
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« Reply #3 on: October 06, 2012, 09:12:24 AM »

Most of the wear and tear in commercial broadcast comes from hours of use slow deterioration.

Most of the wear and tear in amateur use comes from frequent large temperature changes and thermal abuse.

In plain English, commercial service is by filament hours. Amateur service is by abuse and wide thermal cycles. It is explained here:

http://www.w8ji.com/filament_voltage_life.htm

Obviously there is a very difficult to define balance between the two extremes. As often as I see amplifiers, and with all the unprejudiced raw data at my disposal, I couldn't begin to predict the best compromise.

I sure would not cycle my amplifier filaments more than two or three times a day, if I could help it.
« Last Edit: October 06, 2012, 09:15:42 AM by W8JI » Logged
W9GB
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« Reply #4 on: October 06, 2012, 10:25:04 AM »

One parameter always forgotten, is that broadcast stations stay on one frequency (assigned).
SO, the Antenna System and the Transmitter are Tuned and Loaded for optimal results.
The best broadcast engineers (who watched the meters) could quickly see changes in the antenna system or tube performance.

The biggest headache for a broadcast engineer, historically, has been the golden screwdrivers (disk jockeys, announcers, station mgr.) in the audio chain!!

Amateur radio's frequency agility leads to abuse, especially when the operator is impatient.
« Last Edit: October 06, 2012, 10:27:50 AM by W9GB » Logged
K0ZN
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« Reply #5 on: October 06, 2012, 02:39:02 PM »


Tom pretty much nailed it.  If hams use their amplifiers they are abusing them !! (by heating up cold components when they turn them on!) (chuckle.....).

Ya bought, it so USE it !!   

Most of the wear in a car engine occurs when you start it up cold.....but we still drive them and they last a long time. Ditto amps..... with CAREFUL tuning
and proper operation the odds are you will get many, many years out of it problem free.  From what I have seen over the years, the biggest killer of ham equipment
is ham operators !!!  .... it is NOT thermal cycles or filament hours !!

73,  K0ZN
 
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G3RZP
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« Reply #6 on: October 07, 2012, 04:24:55 AM »

Depending on how old you are and what your life expectancy is, it could be worth getting a spare valve and swapping them around every two years.
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KC4MOP
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« Reply #7 on: October 11, 2012, 03:53:56 PM »

Depending on how old you are and what your life expectancy is, it could be worth getting a spare valve and swapping them around every two years.
Under Amateur use and hopefully careful tuning, a typical Power tube, the big guys, ceramic, 4-400's or 3-500's should last many years.
The 572's etc and 811's are easily used up in a short time. Usually from overloads and careless tuning, and the tubes operating out of their limits.
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G3RZP
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« Reply #8 on: October 12, 2012, 02:20:03 AM »

The point is that if you are fairly young and figuring on keeping the amp for years, a spare tube now is a lot cheaper than an 'unobtainium' one in 15 years time.
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PA3GOS
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« Reply #9 on: October 15, 2012, 03:33:49 PM »

That review is written in some kind of foreign language.

Thanks for letting me know. I read the review and then your post. Suddenly it occurred to me I had been reading German...
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W8JI
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« Reply #10 on: October 15, 2012, 04:36:33 PM »

Under Amateur use and hopefully careful tuning, a typical Power tube, the big guys, ceramic, 4-400's or 3-500's should last many years.
The 572's etc and 811's are easily used up in a short time. Usually from overloads and careless tuning, and the tubes operating out of their limits.

I wouldn't trust a 3-500Z for long life any more, nor would I trust a new 4-400A. Emission life is now unpredictable on anything from China.
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N4CR
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« Reply #11 on: October 15, 2012, 11:48:33 PM »

I wouldn't trust a 3-500Z for long life any more, nor would I trust a new 4-400A. Emission life is now unpredictable on anything from China.

So, what does the amplifier of the future look like?

Parallel stages of power FETs?
« Last Edit: October 16, 2012, 12:04:32 AM by N4CR » Logged

73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
WX7G
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« Reply #12 on: October 16, 2012, 12:30:58 AM »

The amateur amplifier of the "future" is solid state has been around for at least a couple of decades with the Ameritron ALS-600 being a good example.

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N4CR
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« Reply #13 on: October 16, 2012, 12:38:41 AM »

That's a long ways from 1500 watts. Legal limit transistor amplifiers are expensive and don't have as good of IMD figures as tube amps did 50 years ago. Is that what we're all going to end up with?
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73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
WX7G
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« Reply #14 on: October 16, 2012, 06:50:17 AM »

The next Ameritron solid state amp up the line from the ALS-600 is the ALS-1300. It runs 1200 watts with an IMD3 of -38 dBc.

Compare this to the AL-82 tube amp with an IMD of -34 dB, the AL-80 at -35 dBc, the AL-1200 at -34 dBc, or the AL-1500 at -36 dBc. None of these tubes amps can beat the IMD3 performance of the ALS-1300 solid state amp.

If you want a legal limit solid state amp there is the Prometheus DX1200L1.



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