[Amps] large tubes in VHF service, tetrode p. suppressors

[John Lyles]

I built 5 kW class C power amplifiers using the 4CX5000A and 4CX3000A on 
108 MHz broadcast. Both were used in the industry for years (RCA) but 
were terrible compared to the short Eimac 4CX3500A. They were all spec'd 
to run at 110 MHz, but there is noticable difference in the lead 
inductance in these tubes.
73
John
K5PRO


> With a spectrum analyzer its rather easy to spot a parasitic and then design 
> whats needed. Many of the big triodes are extremely stable. Tetrodes respond 
> well to grid suppressors, adequate screen bypassing and with a Carborundum 
> style plate suppressor.
> 
> I cant say what these big tubes are like on VHF but Id be tempted to build a 
> rather big cavity for 6M to get around the output C problem. I believe that 
> is used on the FM and TV frequencies.
> 
> Is it worth the bother?
> 
> Carl
> KM1H