HT-33
4CX300A (Pair) Amplifier
The first HT-32A
exciter/transmitter
was acquired on E-bay recently (April 2001) from Pittsburg,PA. I bid on
it
was the highest bidder but it didn't make the reserve. I then bid on the HT-33 amplifier and won it, the same
seller had both items, and offered me the exciter at the last bid price since I was taking the amplifier, and he
really wanted to get rid of both units. When I first saw the units up close in Pittsburg (We drove down) I was
amazed that I even bid on them they were saturated with years of dust, and I figured I would be getting them
in shape for the next six months. Boy was I wrong!
A few pictures of the rig as I got it.
was the highest bidder but it didn't make the reserve. I then bid on the HT-33 amplifier and won it, the same
seller had both items, and offered me the exciter at the last bid price since I was taking the amplifier, and he
really wanted to get rid of both units. When I first saw the units up close in Pittsburg (We drove down) I was
amazed that I even bid on them they were saturated with years of dust, and I figured I would be getting them
in shape for the next six months. Boy was I wrong!
A few pictures of the rig as I got it.
The inside was dusty and dirty, and I
thought, this is REALLY
going to be a challenge.
I removed the cabinet, and the
fan and set them aside for repainting. My trusty light weight paint
brush was
used to clean as much of the loose dirt/dust from the top-side of the rig.
As an aside, I have to say two things. First the BAMA site at K4XL was very helpful in getting the right tubes
in the right places. The manual there helped an awful lot. I wanted a real Hallicrafters repro so I contacted AL
NI4Q, and ordered the original manual repro for the HT-33, which I will add here is different from the HT-33A
and the HT-33B manuals and radios. If you end up with an HT-33, be sure to get the right manual. Alvins E-mail
address is ni4q@juno.com and a VERY good guy to work with, with high quality reproductions on most ham
equipment.
I checked all the voltages and also the operation at the aux connector on the back for full operation of the Bias-relay
inside the unit. This connection requires just a contact closure, in order to operate the bias relay in the amp.
All I can say is they did some real neat planning in this unit, and the functionality is first rate. I was very happy
with the output power from the unit, in the AM mode with 2.5 watts out of the Attenuator (HB) the carrier
power is 350 watts. The Attenuator is a 9 DB job made from 2 watt resistors, I checked that the power out
of the exciter and through the attenuator is around 2.5 watts with my 50 watt bird slug for HF use.
Understand this, if you have one of these units matched up to the HT-32(*), the exciter must be tuned for the
correct power output (into 50 ohms) per the manual. Any excess drive has to be taken care of in the in-line
attenuator (very important). Ah, yes and a blower is advisable for the case of the attenuator as well, I use
a 12 volt fan removed from a PC computer power supply.
Well the HV switching relay gave up the ghost, finally, and I replaced it with an open frame type with 20 amp
contact ratings. While I had the unit out of the case I put in a brand new set (NOS) of 4CX300A Eimac tubes.
The unit is alive and well and hanging out on 40 meters and 20 meters at 7290 and 14.286, see you there.
used to clean as much of the loose dirt/dust from the top-side of the rig.
As an aside, I have to say two things. First the BAMA site at K4XL was very helpful in getting the right tubes
in the right places. The manual there helped an awful lot. I wanted a real Hallicrafters repro so I contacted AL
NI4Q, and ordered the original manual repro for the HT-33, which I will add here is different from the HT-33A
and the HT-33B manuals and radios. If you end up with an HT-33, be sure to get the right manual. Alvins E-mail
address is ni4q@juno.com and a VERY good guy to work with, with high quality reproductions on most ham
equipment.
I checked all the voltages and also the operation at the aux connector on the back for full operation of the Bias-relay
inside the unit. This connection requires just a contact closure, in order to operate the bias relay in the amp.
All I can say is they did some real neat planning in this unit, and the functionality is first rate. I was very happy
with the output power from the unit, in the AM mode with 2.5 watts out of the Attenuator (HB) the carrier
power is 350 watts. The Attenuator is a 9 DB job made from 2 watt resistors, I checked that the power out
of the exciter and through the attenuator is around 2.5 watts with my 50 watt bird slug for HF use.
Understand this, if you have one of these units matched up to the HT-32(*), the exciter must be tuned for the
correct power output (into 50 ohms) per the manual. Any excess drive has to be taken care of in the in-line
attenuator (very important). Ah, yes and a blower is advisable for the case of the attenuator as well, I use
a 12 volt fan removed from a PC computer power supply.
Well the HV switching relay gave up the ghost, finally, and I replaced it with an open frame type with 20 amp
contact ratings. While I had the unit out of the case I put in a brand new set (NOS) of 4CX300A Eimac tubes.
The unit is alive and well and hanging out on 40 meters and 20 meters at 7290 and 14.286, see you there.
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