>I do not agree that the 1200 is better than the 1500 and here is why. The
>1500 has only 50 watts of filament wattage verses the 1200 at 150 watts.
>The 1500 does not need a neutralizing capacitor at the tube, the 1200 does
and will
>oscilate if that little neutralizing circuit changes for some reason.
** The "neutralizing" circuit in later production Al-1200s reportedly
makes the tube more prone to oscillate at the AL-1200's VHF anode
resonance than earlier models which do not have "neutralization". A
possible reason for this is that a neutralization circuit can not
simultaneously neutralize at both VHF and HF, plus - perfect
out-of-phase cancellation at 14MHz becomes positive feedback at 100MHz.
, Heath and Gonset found this out the hard way in the Warrior and the
GSB-201. {the well-intended but not well thought-out "neutralization"
circuit originally appeared in the RCA tube manual}
>The 1200 wants more than 100 watts drive for full output, the 1500 needs 65
watts for
>1500 watts output. They cost about the same, depending on where you buy
>them. I have been using 8877's for over 30 years now without one failure!!
Some guy's
>cry about the 25 watt grid, what about the 4 watt grid in the 3CX800A7??? I
>have worked on several 1200's because they blew the tubes!! Nuff said?
>
** Did they grid-filament short?
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|