[Boatanchors] Mercury Rectifiers

[Jim Wiley]

Of course, the other "fix" is to replace the 866 tubes with 3B28 types.  
No mercury vapor problems, no long preheat required, etc.  3B28 tubes 
are Xenon filled, and don't glow nearly as much as 866s do (they do 
glow, just faintly), but they are a whole lot more forgiving.  And, if a 
bit of heresy may be permitted,  a couple of diode stacks from otherwise 
defunct microwave ovens will make a tidy replacement, give a bit more 
B+, save some cabinet heat, and some electricity (no filament 
transformer), and are "instant on".  I guess it depends on whether a 
person cares how something looks, or how it works.    Each to his or her 
own.   I replaced the 866 tubes in my old Heathkit "Warrior" amplifier 
(4 X 811A), first  with 3B28s and then later with diode stacks - and 
never looked back.


- Jim, KL7CC



Nick England wrote:
> I sent John a copy of the relevant pages in the RCA Transmitting Tubes
> manual TT-4 which has a very good discussion of the topic. RCA says
> Preheat and Condition.
> Summary -
> Preheat with normal filament voltage at least 30 minutes with no anode voltage.
> Let cool and condense.
> Then Condition at normal filament voltage and apply 1/6 normal anode
> voltage (after the usual mandatory recommended warm-up period) for 5
> minutes. Gradually increase the anode voltage over 30 minutes. If a
> flashover occurs during this process, reduce anode voltage until
> flashover ceases, maintain this reduced voltage for a few minutes,
> then resume the treatment.
>
> http://www.we0h.us/Amateur_Radio_stuff/Books/RCA-TT-4-Transmitting-Tube-Manual.pdf
>
> cheers,
> Nick K4NYW
>
> On Mon, Apr 23, 2012 at 11:31 AM, J. Forster <jfor at quikus.com> wrote:
>   
>> Hi,
>>
>> Is there an issue with Mercury pooling in rectifiers, like the 866, in
>> long term storage that would cause them to blow over more easily?
>>
>> If so, is there a fix?
>>
>> Best,
>>
>> -John
>>
>>     
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