[Collins] RE: {Collins} My 30L1's are so happy with 572B's
ROD J MURRAY
rodmurray1246 at msn.com
Wed May 11 13:31:19 EDT 2005
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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