Date: Mon, 5 Dec 2016 17:25:04 -0600
From: Mike Waters <mikewate@gmail.com>
To: "amps@contesting.com" <amps@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
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