[Amps] 1200 vs 1500 triodes

[Joe Isabella]

Thanks for an excellent post, Dave.  I've had my RF Parts branded 3-500ZGs almost a year now
running AM @ 300 to 400W carrier on 40 & 75m and haven't had a single hiccup.  I also run SSB &
CW, on many other bands with a 75/40/20m dipole antenna and letting the amp load it (Where I run
AM, the ant is a good match).  I get a good dip in the plate and grid current is okay (less than
250mA @ full output).  I'm certainly interested in how these tubes age -- however, the RF Parts
3-500ZG has a full 1 year warranty and a prorated second year -- you should have been able to get
two new ones from them for the price of one (at 18 months into the warranty).

Joe,
N3JI

> My experiences with the Chinese 3-500Zs has been questionable - a set of RF 
> Parts house band tubes shorted out in my Henry 2K-3 (3300V no-load) after 
> only 18 months, and this is in an amp which is only used on 80M.  The 
> previous Eimacs lasted 20 years...
> 
> Like they say, your mileage may vary.
> 
> 73,
> 
> Dave/K8CC
> 
> 
> 
> At 08:52 AM 10/24/03 -0600, John T. M. Lyles wrote:
> >I vote for the 3CX1500A7/8877-based amplifier also. I helped design an FM 
> >broadcast amplifier using it in 1983, and it easily produced 1500 watts of 
> >CW output class C at 108 MHz. Last year I converted a RF Power Products 
> >plasma generator from 13.56 to ~4-5 MHz for a scientific application. It 
> >had a questionable old tube in it, as it was pulled from another 
> >experiement in a different lab. When I finished, it fired up immediately 
> >at 1200 watts without a burp, no 'gas', no 'oscillations', very stable.
> >
> >That tube has a myrad of applications, and even though expensive, it is a 
> >good part. There have been periods (as with many tubes) where the mfr had 
> >a production glitch. However, based on the limited application of the 
> >3CX1200 in ham amps, and the domination of commercial and 
> >scientific/medical/military apps for the 8877, the answer is fairly obvious.
> >John
> >K5PRO
> 
> 
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