>Of course Rich it works very well, especially on this old chestnut! It
>reminds me of the re-runs we have on BBC TV in the UK.
>
>Still I must admit without you having a dig at Tom when he surfaces, I would
>begin to worry.
When Tom finally admits that AC circuit analysis is valid for vhf
suppressors, that more than 20w is needed to boil gold from a 50g grid,
and when he admits that Ni-Cr alloys have more R as freq increases, then
the party is winding down.
Have phun
>As I approach middle age, it's nice to know that some things
>in life are dependable :-)
>
>Conrad
>
>-----Original Message-----
>From: 2 [mailto:2@vc.net]
>Sent: 02 March 2003 17:36
>To: conrad@g0ruz.net
>Subject: RE: [Amps] AL-80B questions
>
>
>Conrad -- Does your Delete button work?
>
>>Here we go again (GROANNNNNNNNNNNNNNNN.............)
>>
>>Conrad G0RUZ
>>
>>-----Original Message-----
>>From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
>>Behalf Of 2
>>Sent: 02 March 2003 12:30
>>To: Tom Rauch; AMPS
>>Subject: Re: [Amps] AL-80B questions
>>
>>
>>
>>
>>>
>>>>
>>>> 1: Does this sound like a symptom of parasitic oscillations?
>>>> I thought the 3-500Z was pretty rugged with respect to faults.
>>>
>>>Parasitics, even assuming they would occur, can't cause tube failures
>>unless
>>>you see some solid evidence of excessive current on meters.
>>>
>>A jump to 250mA of ZSAC is not a clue?
>>
>>>I don't know what time period you are talking about, but I've had several
>>>Amperex 3-500Z's fail in my own equipment. Amperex, like all foreign tube
>>>companies, is a bit difficult to work with. My last conversations with
>>>Amperex were only through Richardsons Electronics(who owns Amperex), and
>>>involved 3-500Z grid-to-filament shorts.
>>>
>>>I had four 3-500Z tubes in a test fixture cycling only the filament
>>>off-and-on once every minute, and within a day two tubes failed. In a week
>>>they were all bad. All of them failed because the center of the filament
>>>helice moved over and touched the grid.
>>>
>>>My conclusion is the repeated thermal cycling of the filament, and a
>>>material or assembly flaw in the tube, caused the helice to move the few
>>>thousands of an inch required to cause a short.
>>>
>>It takes more movement than this to short a 3-500Z.
>>
>>>> 2: Does anyone know of any problems with recently built Amperex bottles?
>>>
>>>Absolutely there are.
>>>
>>But Tom Rauch is apparently the only person on this planet who is
>>convinced of this.
>>
>>>> 3: I'll probably help him install the parasitic supressor kit somethime
>>>>this week. Are there any other things to look for or suggested
>>corrections
>>>>to this thing that would make it less prone to eating another tube?
>>>
>>>Put a dead-chicken leg over the cabinet, and say a prayer instead. It will
>>>be more effective.
>>>
>>The recognized amplifier expert plays the Ad Hominem Card.
>>
>>>Seriously, ask him how much often he cycles the amp on and off. Also be
>>sure
>>>voltages are set correctly on the power transformer taps, and that there
>is
>>>no error in filament voltage. Ameritron's transformer vendor, Schumacher,
>>>moved to Mexico about a year or so ago and transformer quality was
>suddenly
>>>horrible. Bad connections were the least of the problems (it looked like
>>>they soldered transformers with a hot rock), there were also some build
>>>problems in transformers.
>>
>>Say what ?
>>>
>>>I'd assume Ameritron measured filament voltage at the tube, but they might
>>>not have measured it correctly or with a good meter.
>>
>>So is Tom Rauch still employed by Martin F. Jue ?
>>
>>> The quality of
>>>technical people is dropping like a rock as time passes. I'd re-measure
>the
>>>filament voltage, especially in light of the nature of tube failures.
>>>
>>Grid-fil shorts from too much filament V ?
>>
>>>Make sure your friend isn't needlessly cycling the filament off-and-on,
>>>since the failures are on-and-off cycle related in tests I have done. I
>>knew
>>>a guy who ate 3CX1200D7's in a Henry like pop-corn because he cycled the
>>>filament off and on about ten times a day. He'd get about two months on a
>>>tube.
>>>
>>The 3cx1200D7 has no spec on fil inrush current.
>>
>>>Remember you are dealing with a white-hot filament
>>
>>1830 degrees K is hardly white hot.
>>
>>>that has one common
>>>mechanical support point *at the very bottom*.
>>
>>There's a ceramic support at the top of the filament.
>>
>>>The filament is about 2-3
>>>inches long when wound in a tight helice, and is thousands of an inch from
>>>the grid. Even if the tube is built properly, it isn't a good idea to
>>>heat-cycle the filament needlessly.
>>>
>>>Ask him how often he turns it on and off BEFORE you tell him anything
>else,
>>>and see if it is abnormal. Also be sure he knows to keep operating grid
>>>current below 125-150mA on carrier.
>>>
>>Eimac has no such advice in the specs.
>>
>>>73 Tom
>>
>>- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
>>www.vcnet.com/measures.
>>end
>>
>>_______________________________________________
>>Amps mailing list
>>Amps@contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>>_______________________________________________
>>Amps mailing list
>>Amps@contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>>
>
>
>- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
>www.vcnet.com/measures.
>end
>
>
>
>
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
end
|