[Amps] 8877 Plate Voltage

[Steve Bookout]

I second that!

I've been running one @4200, or so, since '85 with no issues.

22 watts in gives me 1500 out.  A 3 db pad sure would make it less touchy, when tuning.

73 de Steve, NR4M



On Jun 30, 2012, at 18:50, "Jim W7RY" <jimw7ry at gmail.com> wrote:

> It will be VERY EASY to drive at this voltage.  Probably around 25 watts for 
> 1500 out if it’s a good tube. I'm thinking of putting a 3 or 4 dB attenuator 
> into the input to get the drive up to around 70 watts or so. Mine runs 4100 
> volts no load.
> 
> 73 and good luck!
> Jim W7RY
> 
> 
> -----Original Message----- 
> From: Charles Bibb
> Sent: Saturday, June 30, 2012 2:33 PM
> To: amps at contesting.com
> Subject: [Amps] 8877 Plate Voltage
> 
> 
> Starting a new project.
> 
> I'm collecting parts for a new HB 8877 amp.  One really nice part
> that I've recently acquired is a massive transformer for the HV
> supply.  This transformer came out of a commercial FM transmitter
> that ran an 8877 at 1 kw continuous duty.
> 
> While that power supply used a choke-input filter in the HV supply, I
> want to run the higher voltage obtained by a cap.-input filter. With
> a cap.-input filter, however, the HV supply will be a tad over
> 4150VDC, using the "best" primary taps available. Can wire for
> higher, but not any lower.
> 
> My question(s) is/are:  How critical is Eimac's "absolute maximum
> ratings" as far as plate voltage is concerned.  I know that under
> load, with acceptably regulation, the plate voltage will be about
> where I want it at 3800V.  Is the slightly-too-high potential on the
> anode under no-load a problem? Or, should I just not worry about it
> and "let 'er rip, tator chip".
> 
> Anyone have experience here?
> 
> 73,
> Charles - K5ZK
> 
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