[Amps] Stock up on tubes?

[Jim Thomson]

Date: Mon, 5 Dec 2016 17:25:04 -0600
From: Mike Waters <mikewate at gmail.com>
To: "amps at contesting.com" <amps at contesting.com>
Subject: Re: [Amps] Stock up on tubes?

Good answers.

Question on #2 below: Is the power transformer in the SB-220 conservatively
rated, as the one in the SB-200 is?

Some hams have replaced the 572-Bs with GI-7BTs, and the SB-200's
transformer handled the ~50% increase in power output. And I do believe
that the SB-220's is considerably beefier than the Drake L-4B's.

Just curious.

73, Mike
www.w0btu.com

##  The SB-220  plate  xfmr is rated at 500 VA  CCS. Dont even think
about running a SB-220 at 1500 w on CW..or even 1 kw.   Back in the mid 70s, folks,
esp contesters were replacing the plate xfmr in their SB-220s.   Back then
a replacement from Heath was a meager $35.00 

##  The xfmr in the L4B is rated at  850VA  CCS.   Its good, but dont operate it
on 50 hz, it will run blazing hot. 

##  IMO,  replacing the  3-500Zs in a SB-220  with a single 8877, would be
a huge wasted effort.   Everything from the cooling to tuned inputs, to
bandswitch to PI net output + TR relays and also B+ supply would have to 
be replaced.... IE: the entire amp.  

Jim   VE7RF