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Author Topic: What affects - if any does storage have on an AMP?  (Read 2908 times)
WB9TEV
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Posts: 60




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« on: December 07, 2004, 07:09:07 PM »

I recently have bought a 2 1/2 years old Ameritron 811H. It has been stored for 2 of the 2 1/2 years since it was originally purchased by the first owner. Is there any chance that just the act of storing the amp would cause any problems? I know it has been stored inside a bag/box for almost 2 yrs but stored inside the house actually in a closet. high and dry. i also assume the bag obviously would not be air tight just wrapped to keep dust  out.  My thoughts are that nromal storage of store stock or manufacturer's stock might sit that long from time built to time sold. Anyway, either way is there also some thing I should do or maybe better said NOT do when I first re-start this amp?

It is in perfect cosmetic condition and was perfect functionally when stored.. I assume it should be still ok..

any thoughts..
Thanks
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W5HTW
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« Reply #1 on: December 07, 2004, 07:18:57 PM »

For that period of time, there would not likely be any bad effects.  Over a period of a dozen or so years, electrolytic caps tend to dry.  The other factor is an accumulation of dust, which is probably not too likely since this unit was stored in a plastic bag.  I would say you're safe to go.  I would, though, fire it up without drive for perhaps an hour, before applying drive.  Listen for problems such as fizzling or arcing, but I doubt you'll have any.  And, of course, before firing it up or plugging it in, I'd give it a reasonably good visual, to be sure no wires are dangling loose.  That, though, would depend partly upon why it was stored.

Ed
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W6TH
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« Reply #2 on: December 07, 2004, 07:44:58 PM »



If you have any doubts and want to be sure, just do the following different ways.

Use a variac and bring the voltage up slowly.

If no variac, Go inside the amp and change wires to 220 volts ac and try turning on amp with 110 volts ac.

You may also put a 60 or 100 watt bulb in series with the line cord amp.

Lastly you can plug in the amp if it is set for 110 volts ac and put the voltmeter of the amp on voltage, turn amp on for just one second very quickly and turn it off.. Watch the voltmeter go to full voltage and then watch it slowly drop down as you turn off the power. Do this several times and if nothing snaps or pops, I would say all is ok to run your amp.  Run it for a 15 or 30 minute idle and then go and put it into operation.

.:
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W7DJM
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« Reply #3 on: December 07, 2004, 09:15:12 PM »

It would not hurt a thing to leave the amplifier turned on, in standby (unkeyed) for an hour or so.  This will help "burn" any gas out of the tubes.
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AE6RV
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« Reply #4 on: December 09, 2004, 06:08:46 PM »

I've gotten a few vintage radios lately, and one problem with them is mold and mildew.  Storage for just a few years shouldn't be a problem, unless it's outside or basement storage.  But, if it stinks, it's got a potential problem with all that high voltage in an amp.  Deal with that using soap and water and maybe even alcohol before you try to fire it up.

Bob
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WB9TEV
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« Reply #5 on: December 11, 2004, 02:39:49 AM »

Well I received the amp looks really clean inside and out.. checked it all out very close.. one of the tbe tubes appears to have a blackened in the lower glass at one spot above the base. Does that mean anything important at this stage.

second question.. I decided to do the quick switch on and off to see what happens.. man that was exciting.. flip switch on and amp lights came on kinda loud spark and smell of sometign burnt. also it took such a chunk of inital power it caused my computers to reboot that are on the same line.. swichted it all off right away pulled plug and took case off again.. did not see anything that might indicate anything burnt etc.. still looks clean.. and all compnonets look good
sooo being a brut for punishment I put the case back on and hit the switch again. this time all seemed ok.. at least for about 3 to 4 secs then a small pop and i  could see a little arc at the vents near the 4 tubes. switched it off.. seemed ok so switched it back on (I know I know).. anyway this time all was fine.. had on now abt 1 hr no problems  voltage reads a little lower then my other 811H on same line this one reads 1600 and the other reads 1800..

anyway decide to try a small load into it works fine at least it appears to.. now more questions.. It appears using the same exciter and antenna I can not get quite the output that the other  811H gets.. where on the other I get 600 + on 20 meter with 40 to 50 watts drive seems this amp only want to do about 450 to 500  or so.. can that be an indication that the blackened tube (or one of the tubes) are bad??  How canyou check a tube all filiaments do light

one more questions since I have the other 811H what problems would I be causing if I swapped the 4 tubes from the other amp to this one? I thought that may tell me if a new set of tubes would help with the  lower output of this amp. OR mayve this lower output is just the lower HV I get between the two

Also.. any ideas about the start up problems stated above?? it is running fine right now stil showing only about 1600 volts but I have tested it on 3 bands seems just fine just a little lacking in power output..
thanks for any suggestions.. I would like to hear opinions about swapping the 4 811A form the know good amp to ths one for a test..
thanks
Dan
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WB9TEV
Member

Posts: 60




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« Reply #6 on: December 11, 2004, 02:44:21 AM »

Little more update/info..
i found what I thikn the reason for the lower HV voltage between the two amps (the one I just got) is wired from the factory 120 volts default and I get 1600 volts the amp that I get more power out of is wired for 100 volts at the transformer and gives me 1850 to 1900 volts. Could this be the difference in output or the blackened tube?? I still wonder what trouble i get into by swapping out the 811a between the two. actually I believe the older amp wired for 100 volts and giving me 1850 to 1900 volts might actually be the one that should be changed to prevent early death to the tubes.. manual says nominal 1700 volts///
anyway you guys are the experts I am most concerned about he startup spark, large power surge  and smell but might that be due to sitting 2 yrs..It runs just fine now and seems to have power out but not as much as the other older amp tapped at the 100 volts)


any and all ideas are appreciated.. thanks
Dan
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K7KBN
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« Reply #7 on: December 11, 2004, 08:47:25 AM »

The blackened area you mentioned inside the glass on "one" of the tubes is probably the residue from the "getter".

When tubes are/were assembled, the manufacturer had to be sure that all the air was out of the envelope (that's why they're called "vacuum tubes", after all!)  However, good vacuums are quite hard to come by.  What they did was to put a small amount of flash powder, or a piece of wire connected to the base pins.  When the envelope was sealed, they'd put power to the wire/powder, which would flare up and "burn up" all of the remaining oxygen inside the envelope.  The visible result of this is the black smudge you'll see in virtually all vacuum tubes.
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73
Pat K7KBN
CWO4 USNR Ret.
K0JKJ
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Posts: 25




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« Reply #8 on: December 11, 2004, 11:29:53 AM »

Well let's see 600/4 = 150 per tube. Amp A has 4 good tubes and 600 watts+ out, amp B has 450 watts out and X? number of good tubes. Perhaps three and one that arced over?.

I had this problem with a AL-811 of mine. One tube was arcing over and when it didn't the output power was low. The arc didn't start out until I replaced a troublesome Plate current switch/ voltage switch.

Note that running an amp wired for 100 Vac on 120 Vacmeans that not only is the plate voltage ~ 20% higher so is the filament voltage. This is not a good thing for tube life.

As for swapping the tubes this might help with isolating the problem.

I'd also look for burned components in the sparky.

All electronics runs on smoke! When the smoke gets out of electronics they quit working so it must be true that they run on smoke ;-)
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