[Collins] RE: {Collins} My 30L1's are so happy with 572B's

[joel hallas]

Interesting. I use 811As in my Ten Tec Centaur, and am working my way 
toward the bottom of my stock. Are there some brands of 572Bs better 
than others? The Centaur tubes are horizontal as in the 30L-1, not sure 
if that makes a difference.

Thanks much!

Joel, W1ZR

ROD J MURRAY wrote:

> I agree with Yves.  The transfer curves (gm) of a 572B are just about 
> identical to an 811A.  Your 30L-1 "sees" no difference between these 
> tubes.  It puts out no more power, it draws no more current from the 
> power supply, it's transparent to the amp.   If however your line 
> voltage is higher than normal, or your antenna is somewhat mismatched 
> or you didn't tune up the amp well enough, the 572B's will survive 
> whereas the 811'a will start to glow this bright cherry red.  The 
> plates can get so hot that you melt a big hole in them.  I've seen it 
> many times.  Don't think of the 572B's as being a "more powerful" tube 
> than an 811A (although they can be when installed in an amp with a 
> higher plate voltage), think of it as being a more heavy duty tube 
> than an 811A.
>
> I use 572B's just because I don't like having to replace tubes.
>
> 73'
>
> rod (K1ROD)
>
>> From: "Yves Pautard" <wn4i at access4less.net>
>> Reply-To: wn4i at access4less.net
>> To: <collins at mailman.qth.net>
>> CC: "collins at listserve.com" <Collins at listserve.com>
>> Subject: {Collins} My 30L1's are so happy with 572B's Date: Wed, 11 
>> May 2005 05:55:49 -0400
>>
>> DONT expect any more power from 572B's ( yes you still need 4 )
>> ...I dont agree at all with you ...the 572B are the same as 811A's
>> execepted  they can take 2700 volts or more  and the plate is very 
>> strong
>> made of Graphit
>> You have nothing to do to use 572B's ...like I do since 1983 with no 
>> Problem
>> what's oever ......same plate current ,  same bias ,  same output  
>> because
>> the 30L1 can only supply about 1900-2000 VDC ...( with a good voltage
>> doubler power supply using BIGGER capacitors like in my in kit ...still
>> available )
>> They have been made to replace the fragile 811A's ....but also usable 
>> with
>> more plate voltage .....if you have a chance to use them on  
>> 2700-3000 Volts
>> amplifiers.
>> YES never move a 30L1 when it is ON .
>> Alway make sure the hot side ( BLACK wire ) of the power cord is 
>> going to
>> the tips of the fuse holders .....some ealier 30L1's comes reverse 
>> from the
>> factory. (DANGER)
>> You will never found any holes in the middle of the plates like in the
>> 811-A's
>> 73
>> Yves Wn4i......            wn4i at arrl.net
>>
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>
>
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