Old HB transmitters coming my way

[Opcom]

But it's really HOT outside these days..

These were built by Dennis Brady (SK) in the black crinkle rackmount style with vintage parts, and he left them to me so they would be  cared for and used. So it's time to disassemble the racks and move them to my place.

I'll post more transmitter insides as I am able to. Should have much better pics once at my place and with a real camera, I hope to get them back on the air at some point. They were in daily use until Dennis got ill.

One is the single 250TH transmitter, the other is the push-pull 808 transmitter. There are a total of 5 transmitters, each was put on one band. One's on 30M.

The modulator not shown has been through several iterations, but now uses 808s into a BC-610 mod transformer. The speech amp, driver, RF oscillators and drivers are all tube type, though he was using DDS units instead of crystals at times. There was no slopbuckit, just CW and AM.

Just thought these would be nice to see.

[KL7OF]

Thanks for posting....more please when you get a chance....Steve

[WD5JKO]

Thanks Patrick...

I had talked to Dennis many times when he had that 808 transmitter on the air.

Just wondering if the Colonel Tucker Tx is still operational?

A group will be on every Saturday at 11 am local on 7160.

It has been at least 5 years since I heard you on the air! We miss you.

Jim
Wd5JKO

[W3SLK]

Try to hook up with Duane, KK4AM. He is 'owner/operator' of Cactus Ridge RV Park just south of San Antonio. I have been prompting him to get a wire up in the air and modulate the aether again. I'm sure he would be interested in a rig if you plan to sell any. East AMer from wayback!

[Opcom]

Thanks Patrick...

I had talked to Dennis many times when he had that 808 transmitter on the air.

Just wondering if the Colonel Tucker Tx is still operational?

A group will be on every Saturday at 11 am local on 7160.

It has been at least 5 years since I heard you on the air! We miss you.

Jim
Wd5JKO

I fired the Colonel up and ran some plate current a month ago - -seems to be in order. It has been a very long time. I guess most of my free time has been consumed with my parents' estate, which should be closing this month. Lots of last minute hoops to jump, popped up by the title co. I understand that is normal. Dennis's estate has been a long time delayed but now that the sale is done I just have to get those TX and their support parts/gear to my place. No telling when they might get on the air. I have to do a major cleaning out of parts and stuff in my shack so I can rack them all up in 'proper' racks later. Guess I have had to put hobbies aside. Also, the sewer line, water heater, washer, and dryer have all had to be replaced in the last three years, as well as some major vehicle repairs to keep the Honda Odyssey on the road. Also, the ladder line came off the dipole in a big wind storm though and I have to get it re-attached. so much has been going on but i hope to get caught up this year.

[Opcom]

Try to hook up with Duane, KK4AM. He is 'owner/operator' of Cactus Ridge RV Park just south of San Antonio. I have been prompting him to get a wire up in the air and modulate the aether again. I'm sure he would be interested in a rig if you plan to sell any. East AMer from wayback!

Anything's possible, if I can catch my breath long enough. I don't want to sell them. It was actually an inheritance.

[Opcom]

Cleaning the 'leftovers' out of the back yard shed today. LOL people missed some hidden goodies there, but the heat was bad those days and only about 80% was sold from there.

I had do go through boxes and tubs of items, determining what to put in the recycle pile and what to keep, These little gems showed up.

The capacitor looks like a '30s item. Despite it being a 'USA' company, it was made in Germany.

The transformer is a microwave oven filament transformer. Pretty scarce these days. Hope it can be modded/rewound to supply 5V@6.5A for an 8020.

[Opcom]

xfmr

[Opcom]

There are 5 racks of transmitter there. Each has to be dealt with, units removed if need to put in  a cabinet-type rack for transport, etc. Not going to keep the 'relay' style racks. It's very hot so I can only work a few hours in the mornings.

1st rack:
PP 3C24 amplifier, three Heath HP-23 power supplies to run the exciters: 2 Millen and one HB 838-1625 (which has a remote plate current meter, and an interesting home made shield made of two tin cans around the 1625, with windows cut in it to observe the 1625 plate). That exciter did duty for several amplifiers and there is a switch box externally to connect it to any of 4(?) amplifiers.

838-1625 exciter:

[Opcom]

Three Heath HP-23 power supplies.
These were to run a Heathkit transmitter, so they have plenty of power for an exciter. The 800V outputs are in use for the 807 and 1625 plates. They also have 6.3 and 12.6 volt heater outputs.

[Opcom]

Two Millen 90800 exciters:
Might have been modded a little but not much. Dennis used DDS VFOs to get frequencies if a crystal wasn't on hand. There's a separate amp not shown that gives crystal-level output for driving the exciters in lieu of an actual plug-in crystal. The exciters have 6F6s installed in place of 6L6s, to drive the 807s.
The inside pictures are of just one of them.

[Opcom]

Push Pull 3C24 amplifier:

Works on 20/17/15M with the coils present (there are many coils for these amps and I'm trying to get all of them together.) Has its own power supply. The plate modulator can serve all these amps and will be shown later when I get to that rack.

All these amps are built after the articles of Frank C. Jones. Not copies, but the same principles.

[Opcom]

Push Pull 808 amplifier:

has own power supply and controller (relays. no fancy stuff, just simple stuff that works) in same rack. All the previous stuff except the Millen exciters was in a small relay-style desk rack sitting on top of this rack. It all counts as 'one rack' for this project. 808's no slouch. I believe this one is on 80M.

(that's all for rack 1)

[Opcom]

Rack #2:

This was an old style 'relay rack' but modernly made of thick aluminum as would be in use today. It's the kind that can tip over if not bolted to the floor or seriously weighted down.

This rack would never tip over with the 150 Lb HB power supply in the bottom of it. All the weight's at the back. The Millen 90881 amplifier is just above the power supply. Higher-up light weight front-mount rack shelves were bolted into the rack and used as places for relay boxes, RF routing switch boxes, VFO+buffer, and coils storage for some of the HF bands.

I only got a pic of the lower area of this rack, just the amp and power supply. Some of the coils are also shown. So far most of these amps are using the BC-610 size coils and on the inputs, the smaller coils that plug into a 5 pin pillar base socket like an 807.

[Opcom]

Here's the Millen 90881 amp.

It's on 20M and running T-40s. There are a few spares and TZ-40s with it, and it'll use other tubes as well.

The close-up with the small coil is the input circuit.

[Opcom]

top of Millen amp to show the plate wiring and neutralizing cap setup. The box on the right is a shield Dennis made, from some other cover, to go over the input coil.

[Opcom]

The power supply! It looks messier than it really is. Just crowded! It supplies beside the plate voltage, bias, filament a control voltage, and has soft start, hi/lo B+, and HV keying relay built in. It, or the plate section anyway, looks much bigger than the Millen would need.

Some specs and guesses observed from it:

Plate section:
 -Basler plate transformer: C 36560 ?, 10488.001 ?
 -Semiconductor Bridge rectifier.
 -Choke: 8-35H swinging, 300-400mA?
 -Filter Capacitor: 4uF / 3000V oil
 -Bleeder esistor 100K
 -Inrush limiter: ceramic cone heater element.

Filament transformer: 7.5VCT for two T-40s.

Other transformer unknown.
Variac, unknown function.

Bias section:
Bias transformer 410VCT, FWCT semiconductor bias supply, choke input type,,10uF filter capacitor, electrolytic, 2200 Ohm resistor: bleeder or grid leak bias function?

[Opcom]

This nice little switch was also attached to the same rack (#2). It was to select whether the exciter drove the Millen or 808 amplifier.  

The anode is from an 808. Found it between racks. 

It has little nodules or granules on the inside of the plate. The material is Tantalum, so it's supposed to be very high-temperature. Wonder if it was arced-over or what happened there to ruin the tube.

[Opcom]

The next 2 racks #3 and #4 don't need any disassembly to move them, just disconnection. Each one has its own power supply and amplifier. One is the 250TH, the other not sure if it's been shown yet, maybe the 808 amp. But once they are away from the row of metal, better pictures should be available. Probably tomorrow.

[Opcom]

Rack 3:

The 808 amp - says HK-54 on the front, may have had those 20 years ago.

There are better pictures of it. The cross neutralization wiring is interesting.

The power supply was originally a commercial negative 750V unit, but has been converted to about 2KV and a lower setting, maybe half.  

Notice the yellow tag in the grid compartment.

[Opcom]

Rack 4:

The 250TH amp. Better pictures now that it's out. Can't see much of the power supply. Dennis liked everything covered for safety reasons and I don't blame him.

[Opcom]

Finally this last picture of the 250TH chamber. I like this one best. It reminds me of a comfortable old room.

[Opcom]

Rack 5:
The audio rack turned out to be very time-consuming because the entire back side of it where all the weight was, had been supported by a single thin leg, and the back of the enclosed section could not be removed without removing the leg at which point it would have tipped over backwards. It was difficult to move it because of the weight, without the leg wanting to bend. Granted it was built to last and would never need to be moved once built, but the risk of tipping over is why I don't like the old style relay rack. Everything had to come out the front, but I had to access the back to do it.

I thought it was one big modulator, but it turned out there is one speech amp and two modulators with each their own filament, bias, and keep-alive supplies. One plugs a low-Z cable from the speech amp into the desired modulator.

One modulator is for the 808 amp, and one is for the 250TH amp. Therefore, they are quite different in power output.

Both use a pair of 808 tubes. The modulator for the 808 amplifier uses an ART-13 modulation transformer and the modulator for the 250TH uses a BC-610 modulatio transformer. Each modulator 'steals' plate voltage from the associated transmitter. AM/CW function ceramic switch is at the modulator for each combination. Each modulator has its own set of meters. The speech amp has just one level meter for itself.

These equipments were built in a modular fashion, each having a power supplly chassis and a modulator tubes chassis. All of these simply 'sat' on rack-shelves so they could be slid out once the stuff in back was disconnected. The modulation transformer for the larger modulator is outboard of the chassis, at the bottom and all the way to the back of the enclosure. The smaller modulator is built breadboard-style, and the little ART-13 transformer fits nicely on that board. Can post some good pics tomorrow.

[W3SLK]

OPCOM said:

Both use a pair of 808 tubes. The modulator for the 808 amplifier uses an ART-13 modulation transformer and the modulator for the 250TH uses a BC-610 modulatio transformer. Each modulator 'steals' plate voltage from the associated transmitter. AM/CW function ceramic switch is at the modulator for each combination. Each modulator has its own set of meters. The speech amp has just one level meter for itself.

Those 808's are one of the most buzzardly tubes I have seen! I hope you can get this all up and running. It would be kewl to hear both of these rigs on the air.

[Opcom]

I hope to get it up and running as well. For now, when it arrives here next week, it has to be stored until more space can be made in the operating area.