Burning in an amp

[capten]

I have just acquired a Dentron 160-10L amp with 4 576B Cetron tubes that appear to be in good shape
The unit has been sitting idle for at least a year or so without transmitting,
Is there a recommended procedure to "break it in" before use?
Once it is up and running, how hard can it be run in the first few hours to ensure that the tubes are hot enough for the getter to do its job - full power , half power, etc? I will use an oil filled dummy load, so extended use should not be a problem.
Thanks

 

[capten]

Edit - tubes are 572B not 576B

 

[LtDoc]

Start off with low power/drive and gradually increase it to it's normal maximums. Average warm-up time for typical 572 tubes isn't that long, a couple of minutes should get them to where they should be. How do you tell if the warm up time is long enough? The thing just doesn't get any hotter is one way of judging. How do you measure that heat change? Not having any sophisticated thermometers, I use my hand. That's close enough.
Don't expect 'perfect' numbers, you'll probably never see them (even if the thing wasn't 20 years old). Those 'numbers' ought to be fairly 'close' in a general sort of way though. I also wouldn't 'push' that amplifier too hard until you've got a general idea of what it's capable of. The typical 'gain' from that 'pushing' is never going to make any significant differences in how you're heard. It only lowers the life expectancy of the amplifier.
Nothing 'new' in this, just common sense. Oh well...
- 'Doc

 

[prcguy]

If your amp has 572Bs then its a 160-10M and the only difference is the L version was sold with 811A tubes and the 572Bs are direct plug in replacements with higher plate dissipation.

572Bs have directly heated cathodes and warm up time is only a couple of seconds then their ready for full power. Tubes like the 811A and 3-500Z are also directly heated and once tuned to a frequency the amps can be treated almost like a solid state amp where if you need it in the middle of a QSO you just turn it on and have instant power. They are also very rugged but keep an eye on the plates and avoid heating them past a dull red color during tune up.

Your amp is probably well over 30yrs old and usually the electrolytic HV caps would be questionable but if its been used in the last year it should not be a problem. If you want to be kind to the electrolytics you can power the amp up using a variac with the HV on turning it up very slowly and let it sit for awhile at 1/4, then 1/2 then 3/4 voltage and that can help the electrolytics reform the insulation layer without punching holes in them from internal arcing.

Usually this is best done with a large series resistor ((50k ohm) between the rectifiers and caps with full voltage applied and a current meter to monitor for any glitches. This is a bit dangerous in your amp due to the level of HV so a variac is safe and easier.
prcguy

 

[alex2x572b]

hi
i have been using some 572b from china seems a bit hit and miss
2 tubes seem ok
1 tube have some internal arcing
i burnt them in for 9 hours then very slowly drove them to make sure they would be ok
"you can buy those tubes of the company in china driectly if you need such things

[ solicitation to buy edited out by the moderator ]

cheers alex vk3tzu