[Amps] AL-811 Tube Swap

[Jim Thomson]

Date: Wed, 28 Apr 2021 09:25:01 -0700
From: Richard Solomon <dickw1ksz at gmail.com>
To: Amplifiers <Amps at contesting.com>

<I have an old AL-811 on the Test Bench
<I use when I need a little more starch for
<test purposes.

<I thought about replacing the 811's with
<572B's.

<Any pitfalls on that idea ?

<Tnx, Dick, W1KSZ

###   572Bs  would be the ticket.
Per  W8JI, the 811s  dont have enough anode diss  for modes like
RTTY,   FT-8,  Data, FM,  or  AM .  The UN modulated  CXR on  AM has lousy eff, like  25%.
Do the maths, and the anode diss is  TRIPLE the  UN-Modulated CXR. 

##  The issue is the 811s,   not the  HV supply, cooling etc. 

##  572Bs   would solve those issues. 

Jim   VE7RF