>
>
>
>Does anyone have access to a schematic diagram/Manual for the ole
>Hallicrafters HT-33B amplifier? OR, need a diagram for the final amp tube,
>4CX1500B that sits in the amp. Am about to rebuild this old one and get up
>to the 21st century standard. Trying to salvage as much as possible from
>the original parts. Looking to rebuild using the original metering
>circuitry, convert to grouned-grid...
The 4CX1500B can not safely be operated in g-g. The grid diss. rating is
1w max. However, the tube works quite well in Class AB1 grid driven
config. provided that the grid is terminated with 50 ohms, the grid is
not driven into the grid current region, the screen is equipped with a
c.400v zener-string shunt regulator (biased through a resistor from the
anode supply), and the anode is supplied with c. 3000v. . However, 100w
is Way too much drive, so having an exciter with a Pout adj. is useful.
Adding c. 5 ohms of cathode nfb resistance adds about 15v-pk of g-k
feedback, makes the tube harder to overdrive and a bit more linear.
- As I recall, the HT33 used a choke filter hv supply. If this is the
case, and you plan to use the amplifier for ssb, it is important to
convert to a resonant-choke filter.
- later, Mark
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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