The MEISSNER 150B Story
The Meissner 150B is a Classic WWII transmitter. It was built for the US Army under a 1943 contract. My unit is serial number 500. It is obscenely large and heavy for a 150 watt tabletop rig, weighing in at 305 lbs for just the transmitter and another 40 lbs for the exciter. The TX is 40 inches wide, 20 inches deep and 14 inches high. The transmitter consists of a single 813 modulated by a pair of 811's. There are separate plate supplies for the final and the modulator as well as a LV supply for the speech amp. The HV power supplies use 866 mercury vapor rectifiers. This radio has LOTS of iron in it - 18 transformers/chokes. The frequency coverage is from 1.5 MHz up to 12.5 MHz. The grid input circuit is band switched but the final uses plug in coils as well as plug in mica "padding" capacitors. The exciter unit uses plug in coils and consists of a 6F6 oscillator and a 6V6 amplifier. It has a self-contained power supply with voltage regulators. There is considerable drift for the first hour or 2, so I have been using my Fluke 6011A generator as a signal source for all of my big rigs except the T368. I feed about 3.5 volts from the generator to the grid of the 6L6 and now my "Signal Drifter" is as stable as a rock. The speech amp consists of a 6J5 audio amplifier which is transformer coupled to a pair of 6V6's in push-pull which in turn drive the grids of the 811A modulator tubes.
The story of how I came to own this old girl is as interesting as the rig itself. This was truly a "hamfest special". While cruising the tailgate area at the Berryville, VA hamfest one year, I came across this behemoth of a transmitter sitting in the rear of a van, and I must say that my first impression was something like "what an ugly piece of crap, and it's, well, it's HUGE" It was grungy dirty, it's paint was worn, the glass was broken out of the plate meter and the needle was bent at an odd angle....and did I say it was HUGE? A previous owner had TVI proofed it with tomato soup cans soldered over the meters. It was in total disarray and looked as though it hadn't been used in a long time. And all for a 150 watt rig? Well, the owner wanted a goodly sum for it and I surely didn't need it and, that was that - or so I thought.
It was late in the day and things were winding down at the fester with a lot of sellers pulling up stakes and heading home. I was checking out some test gear near the main prize drum when the Meissner's owner came by and asked those around if they knew of anyone who would be interested in his transmitter for FREE. I told him he should have it announced on the pa system, which he did, and I proceeded to look for bargains before heading home myself. I was making my last sweep when I came by the van with the Meissner and I asked the fellow if he had any takers and he replied " no, and said that he didn't have anywhere to keep the rig when he got home and it would have to sit outside. Well, I just couldn't let that happen and I thought to myself that the transmitter had some nice looking parts in it, so why not. With the help of a John Deere Gator and 3 helpers we got the thing to the parking area and into the little Tercel wagon that I had at the time. Now my physical struggling with this monster had just begun.
If you are getting tired of reading and just want to see the pictures
For obvious reasons it stayed in the back of the wagon (my wife's work car - and NO she wasn't happy) for almost a week until I could talk 3 co-workers into coming out to the house one day at lunchtime and help me get it out of the vehicle and onto a furniture moving cart that I bought for the purpose. Now I was able to push it around the garage all by myself but I knew that sooner or later it had to come out of it's cabinet. By this time the thing was starting to grow on me and I thought that it would make for a very interesting restoration project and a very cool rig if and when I got it finished. I bought another little wheeled cart and with that and a rope-pulley-sling arrangement I was able to remove it from the cabinet, restore it, and then put it all back together without any more physical help of any kind - that is until it came time to move it down to the basement shack. I got my same 3 helpers for that job, a job that proved to be more difficult than it looked since there are no handles or hand holds of any kind on this rig and all 4 of us had to try and share the weight as we went down the somewhat narrow flight of steps to the basement.
It took about 3 months of evening and weekend work to get it finished. I completely dismantled it and worked on one section at a time. The 150B is divided up into 5 main sections. The cabinet of course, the front panel with the wiring harness and the 3 component decks - the final, the modulator, and the power supply/control deck. Since this baby was so hard to work on and I didn't want to have to take it apart for a long time, I replaced every part that I could. All capacitors that weren't oil filled units, and all resistors that weren't wire-wound and in good shape were replaced. I removed all of the TVI suppression bypass caps and of course the meter "soup cans". I was able to lug the modulator/speech amp down to the basement bench and power it up from a bench HV supply, so it was there that I reworked and tested the audio section right up to the 811 grids. I removed the carbon microphone transformer and in it's place installed a high quality UTC line to grid transformer (liberated from a defunct RCA compressor amp) as I planned to use my station "audio rack" with this rig. I installed a small switch on the mod deck to allow plug and play use of a D104 plugged into the front panel jack if I so desired. One of the weak points of this rig was the 866 sockets that were recessed below the chassis - the holes were not large enough and they would eventually arc to the chassis, ruining the sockets. I had to replace all 4 of them with new E F Johnson sockets and then using a dremel tool, I enlarged all 4 holes in the chassis - which seemed as though it was made of heavy boiler plate. The other weak point that all 150B's seemed to share was the modulation transformer and mine had already been replaced with a UTC CVM-3. Back up in the garage, the front panel was stripped and repainted and the cabinet was refinished. The chassis's were cleaned and touched up. This same restoration was performed on the Signal Shifter exciter. The exciter didn't come with it's cabinet but I was able to find a suitable Meissner cabinet on Ebay, which was a bit rough, but after refinishing to match the newly painted transmitter cabinet, it looked good.
Reassembly began in October and it was already beginning to get cold out in the garage in the evening. The rig went back together with the expected physical effort due to it's size and weight. Initial testing looked good. I wanted to use the original design 866A rectifiers for the "visual effect" and I ended up replacing all 4, and so far they have been well behaved. The rig does have time delay relays to prevent the application of HV until the mercury vaporizes. The rig came on line with a good carrier and making 200 watts out to the Bird 43 was no problem. I did have to prop the rig up on jack-stands to make some final changes under the speech amp deck - it was like working under a car!!
This 60+ year old transmitter now proudly sits on it's own special table down in the main W3NP wireless room - the radio shack, that is. Rescued from it's unwanted ugly duckling status at the hamfest, it has become one of my all-time favorite transmitters. It is stable, a pleasure to operate, and it always seems to receive good reports on the air.