The AM Forum

I just came across a nice old rack mounted Remington Rand ultrasonic generator.

It's got a nice Stancor Plate transformer feeding a pair of 866s, choke and oil caps; and an 18-30 khz exciter driving a pair of 810s into an output transformer. I have no idea what the output impedance of transformer is.

I occurred to me that it would be a great start for a KW transmitter since it has the power supply, the 810s (maybe for the modulator) and a nice 4ft tall rack cabinet that is just begging for black wrinkle paint. I may be able to adapt the exciter (or at least the chassis and sockets) for 80-10 meters. The power supply and the 810 with the output transformer is on the lower deck, with the exciter and controls on the upper deck.

The owner wants $150 for the rig but I can probably get it for $100, since he's had it for years and quoted me $85 for it about 8 years ago. I figure the rack cabinet and iron is worth that.

The output current meter is calibrated up to 15 amps so I figure that the transformer output is pretty low Z.

Does anyone have any info on such a rig? I've drawn a blank on Google.

I'll try for some pictures tomorrow. I'm going to take a VOM to the iron before I buy it

Any ideas?

Some of the "Low-fers" might be interested in that 18-30 kHz generator and output transformer.

I'm on my way over to check it out a little further.

It looks like the exciter is tunable in two or three ranges and uses a pair of metal 6L6s to drive the 810s which seem to be in push-pull into the (large) output transformer. There is a tuning card in the back of the exciter with settings from 18-30 kc.

I won't tear anything up until people have a chance to check in and see if it can be used more or less as is.

It's been sitting in the surplus place for at least the last 12 years.

Pictures soon.

Greg

Suunds like it is really wanting to modulate a 4-125 through 4-400 final

I had a Raytheon 10 KHz magnetostrictive element driver (ultrasonic device) that I bought at a gov't auction many years ago, it had a crummy UTC S46 plate tranny, but had a pair of 813 and their filament trannys. After gutting it, I used the chassis and tubes/sockets for my modulator design for Johnson 500. The PS chassis was not reusable, yet.

John
K5PRO

I checked the secondaries on the power and mod transformers and they checked out fine.

I was wrong about the manufacturer though, the machine was licensed to Remington Rand but built by Sheffield Cavitron;probably in the 1950s or 60s.

I did get pictures...the thumbnails are clickable for for full size...

(http://img530.imageshack.us/img530/2750/img4090kf6.th.jpg) (http://img530.imageshack.us/my.php?image=img4090kf6.jpg)

(http://img519.imageshack.us/img519/1640/img4096op8.th.jpg) (http://img519.imageshack.us/my.php?image=img4096op8.jpg)

(http://img186.imageshack.us/img186/6881/img4088cq9.th.jpg) (http://img186.imageshack.us/my.php?image=img4088cq9.jpg)

(http://img186.imageshack.us/img186/9777/img4084jv4.th.jpg) (http://img186.imageshack.us/my.php?image=img4084jv4.jpg)

(http://img212.imageshack.us/img212/486/img4098vq9.th.jpg) (http://img212.imageshack.us/my.php?image=img4098vq9.jpg)

(http://img212.imageshack.us/img212/5813/img4087aj4.th.jpg) (http://img212.imageshack.us/my.php?image=img4087aj4.jpg)

Well, I couldn't resist, I bought the Ultrasonic Generator for $100 and will pick it up later this week; I did pull the 866s and 810s for safekeeping.

Now I've got to start designing a Buzzardly AM transmitter to use the existing parts and cabinet (which is on castors, has handles and is vented on the sides)!

Does anyone have any idea what impedance the secondary would be to feed the toolhead on this thing? My guess is that it would be fairly low, since the output meter is calibrated up to 15 amps.

How much audio can I expect with a pair of 810s for modulators?

Depending on the transducer, they could have series resonated it. So it could be low Z or high, hard to say. You can measure the transformers, but they are probably not wideband devices down to audio. My Raytheon had light transformers that looked like hypersil strapped iron. They didn't have the lamination structure one would expect for power and LF audio.

Pair 810s, 300-400 watts of clean audio, as much as 500 when HV is up.

With the proper transducer and some soapy water you can clean ur removable choppers   ;D

Lots of neat parts there and only a mite dusty.

Self cleaning probablility?

Chinese Dragon?

I did the basic clean up and pulled the exciter section out to get a better look at it. It's got a 5U4 in the power supply and a pair of 6L6s that seem to be both oscillator and driver.

(http://img375.imageshack.us/img375/3826/img4110jj8.th.jpg) (http://img375.imageshack.us/my.php?image=img4110jj8.jpg)

(http://img375.imageshack.us/img375/8515/img4113yl0.th.jpg) (http://img375.imageshack.us/my.php?image=img4113yl0.jpg)

(http://img212.imageshack.us/img212/530/img4128mz0.th.jpg) (http://img212.imageshack.us/my.php?image=img4128mz0.jpg)

(http://img519.imageshack.us/img519/1640/img4096op8.th.jpg) (http://img519.imageshack.us/my.php?image=img4096op8.jpg)

It's all high quality, industrial grade parts and really clean underneath. Now I just have to figure out how to use the panel and chassis for  a transmitter.

The power supply and 810s/output transformer are built onto the the base of the cabinet and not attached to the front panel. Everything is on the surface. All the power switching and drive is cabled up to the bias chassis and connected by plug to the exciter.

(http://img375.imageshack.us/img375/6018/img4121ci3.th.jpg) (http://img375.imageshack.us/my.php?image=img4121ci3.jpg)

(http://img375.imageshack.us/img375/4559/img4116ic7.th.jpg) (http://img375.imageshack.us/my.php?image=img4116ic7.jpg)

This is the schematic for the complete lower section, you couldn't get away with lead lengths like this at normal radio frequencies. The grids are connected to the drivers by about three feet of wire. You don't see selenium rectifiers much these days either.

(http://img212.imageshack.us/img212/7922/img4129fq4.th.jpg) (http://img212.imageshack.us/my.php?image=img4129fq4.jpg)

This is going to take some thought.

I think you are going to have to put some sort of choke at the input of the PS filter.  The 866's may flash over with cap input filters.

Al  VTP

This is the circuit that was there, not what I'm planning.

I believe that's why they put those 1K/50watt resistors in series with the input cap. That puts 500 ohms in series with the cap, not something I've seen before, but it obviously worked OK. I'm not sure why they didn't just go with a choke input filter.

I looked up the transformer and it's good for 3550 volts CT @ 500 ma CCS/625 ma ICAS and weighs 65 lbs; worth the price of the whole thing. There are a couple of nice driver transformers for the modulator in there too, a couple of nice high test filament transformers, and a nice 1,100 v CT @ 175 ma transformer in the exciter; not to mention the tubes, sockets and rack cabinet (which will need a nice coat of black wrinkle)!

Now I've just got to find a design that uses the stuff to it's best advantage.

The output transformer, just replace it with a good modulation iron. I may have something for you, like a 600 watt stancor multitap A3899. it was used with a pair of 810s.  You'd want a reactor with it, to get the DC off the secondary.
You can run 2500 volts on 810s (with suitable bias of course) and get 400-500 watts of hifi audio out of them. Then you need a BIG RF stage. Your P8029 is set up for 1500 volts DC as a CT full wave with choke input. If you can get something more stout, you'd do better. I have a P8031 that will do 1750 at the same 500 mA, if that is any help. Gotta go right now, will be offline for about a week. 73
John
K5PRO