[Amps] Triode Amps

[Kim Elmore]

I’m an admitted B+ junkie. I modified an AL-80A power supply and output circuit for about 3.6 kV B+ under load and got about 800 W out (depending on the band). Cooling is a serious issue with the glass tubes. 

I used the lower voltage primary on my AL-1200 to get 3.6 kV under load (added another capacitor to the HV PSU filter string as well), at the fan speed to maximum, and it makes 1.5 kW easily on all bands with less drive. I had to add some padders to the load capacitor because of the output impedance change. 

I have not run RTTY with it at 1.5 kW as I’m not confident the cooling capacity is up to it. 

Kim N5OP

> On Dec 2, 2021, at 3:19 PM, Tim Duffy <k3lr at k3lr.com> wrote:
> 
> My favorite triode for 1500 watts all day is a single 8877. 4KV and 30 watts
> drive.
> 
> Used 8877s exist and are more than capable for long lives. Some of the 8877s
> at K3LR have date codes from the 70s... still going strong
> 
> 73
> Tim K3LR
> 
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Peter Voelpel
> Sent: Thursday, December 2, 2021 4:16 PM
> To: 'Kim Elmore'; amps at contesting.com
> Subject: Re: [Amps] Triode Amps
> 
> Eimac specifies 890W for a single tube at 3.5KV plate voltage and 740W at
> 3kV.
> 
> 73
> Peter, DJ7WW
> 
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Kim Elmore
> 
> 
> The 3-500Z is an excellent tube, but 1500 W isn't reasonably available 
> out of a pair, even at increased plate voltage
> 
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