[ADXA] BIC Failure

[w5znjoel at gmail.com]

I’m sure glad you clarified that was a BIC lighter failure, not a “Butt in Chair” failure. I first feared you had experienced a physical mishap!!!  😊

 

ZN

 

From: adxa-bounces at mailman.qth.net <adxa-bounces at mailman.qth.net> On Behalf Of Dennis Schaefer
Sent: Friday, January 19, 2024 1:54 PM
To: ADXA <ADXA at mailman.qth.net>
Subject: [ADXA] BIC Failure

 

I learned a long time ago that you need the proper test equipment.  I have a Bird wattmeter, a Fluke VOM, etc, but I came up with a need for something I didn't have.  

 

811A tubes are finicky and you can't push them too hard, particularly on digital modes.  I don't use my AL-811 on digital modes at all, but have been tempted, mainly with the VU4 who could hear very few due to a high noise level.  

 

Tom Rauch is the designer of this amp, and gives expert advice.  He said many were sent out with inadequate fans, causing a lot of 811A's to melt down.  He's correct, because a local here (not John or George or Charles) has done it a few times.  When an 811A melts the plate, it often results in a grid-to-plate short, which is, well.....less than optimum and sometimes exciting and expensive.

 

According to Tom, there is one way to check the fan.  Put a BIC lighter one foot from the air outlet, and if the lighter blows out, your fan is OK.  I didn't have a standard lighter, so I tried the larger BIC lighter I use for my charcoal grill.  The flame danced around but didn't go out.

 

$1.72 later, I had the proper test equipment - a bog-standard BIC lighter.  The amp blew it out every time.  Now I am confident my fan is OK and if I burn up a tube it will be from improper tuning.  I know if I buy three 572B's, I will have adequate cooling for them.  

 

Could I afford to just get a good amp?   Yes - a Mercury would be nice and an Acom or OM would be fine.  I just want to do it this way for awhile, mainly because people say it can't or shouldn't be done.  

 

So the test equipment BIC yielded good results but only with some effort.  The personal BIC is anxiously waiting for Clipperton.

 

73,

Dennis/RZ/still at 1446 but expecting 1450 by the end of the weekend.

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