I stated somewhere, probably more than once, that my interests include early radios up to 1942 and later Hi-Fi from around 1955 to 1979.

Why, you may ask, do I exclude the decade between 1945 and 1955? Cabinets, those rectangular, featureless cubes with doors that degraded further with the "blond", yellow and whitewashed finishes that continued into the 60s.

The problem, for me, is two fold.  First, these designs tend to hog floor space. Second, unless you design a room around them, these consoles don't fit well with most décor. Or even more simply put, they are just not to my taste. I know that my feelings are not universal, but demand and prices over the years do indicate considerable sympathy. I will have to concede that after considerable resistance, a 3 channel Motorola has been added to the display - and I kind of' like it.

 Unfortunately there were some great radios hidden inside of those cabinets. Scott and Meissner were just two of the high end manufacturers that followed this trend. They had to. It was the style of the time.

Fisher consoles are often stripped of their tuners to be installed in cabinets like those that became popular in the 60s and 70s. I suppose that this is preferable to losing the whole console to the land fill, but, one day (maybe today) the original cabinet will be missed.

So when recently I was given a number of these late 40s, upper-end radios, I simply stashed them in the parts room and moved on to the good stuff.  I suppose that fate and my desire to preserve history collided when it became necessary to clear out the parts room - or put a warning sign on the door - Enter at Your Own Risk!

Among these radios was the Scott 510 discussed below and a Scott 800 that I have not addressed yet. But the ones that interested me most were the Meissners. There was quite a collection - none were complete and none had a cabinet.

First there was the 2961 amp - REAL radio candy from 1947! I just could not ignore this PS/amp with push-pull parallel 6L6GA output tubes. Turns out the 6L6s are wired for triode operation which reduces the power output considerably (as compared to pentode operation). This amp/dual power supply was the heart of a 2961 tube radio - I wish that I had the rest of it.

Since I had neither the original 2961 receiver nor the amps for the 9-1093-7 and 9-1093, I built an adaptor to use them in combination as well as with a 9-1091C receiver (later).

At this point I will confess that the original configuration of the 9-1093 had only (ONLY!) 24 tubes, but what the heck. Here is a video. The original coaxial speaker and OP transformer are also missing so I had to adapt -

Meissner 9-1093-7 and 2961   (26 tubes)

The 1093-7 chassis was in the best shape of all of them with the black finish and red lettered labels remarkably intact. Yet it also needed the most work.

Along with the standard restuffing of paper and electrolytic capacitors, this unit also had about half of the carbon resistors way out of tolerance. I was able to replace all of the resistors with NOS carbon comp resistor from my parts inventory. This kept the bottom side of the chassis looking original as well as the top side.

During the parts replacement all eyelets are cleaned and the original mechanical contact is restored prior to soldering. This keep the eyelets and contact strips from "bulking up" with old solder and the old component wire ends also maintaining the original look and reducing the chance of intermittent contacts.

You might note the -7 on this model number. This one is the only reference to that suffix that I have found. The other version is just 9-1093. I have one of each and there are at least 3 very significant differences.

The -7 version has an on-board preamp tube for phono mounted at the end of the FM circuit and inside of the area that shields the last IF, 2 limiters and the discriminator. The other version has a hole/cover in the chassis but uses a separate pre-amp module with 6V and B+ coming from the main chassis. Interesting that the pre-amp must be plugged in in both cases to an RCA input connector.

The -7 version also has the nice black paint and the controls are mounted directly to the front of the chassis rather than being spaced back several inches in the other version.

Meissner 9-1091C

This is another AM FM (mono) chassis from about the same period. It has somewhat more versatility as compared to the 9-1093 since it has it's own power supply and push-pull 6J5s capable of driving almost any amplifier. But, it still does require a separate amplifier chassis. This radio has 17 tubes including a 6U5 eye tube to display signal strength. Like the 9-1093, AM and FM reception and audio quality are very good.

This 2961 amp uses push-pull-parallel 6L6GA wired as Triodes. It has 2 rectifiers. The 5Y3G supplies B+ for the tuner chassis and a 5V4G provides B+ for this chassis.  There is a separate filament transformer.

One of the features of this amp that is notable is the socketed filter capacitors, one for each of the B+ supplies. These caps use a 4 pin socket like the one used for an 80 or 2A3 tube. They are secured by a clamp. This sure would have made servicing the filters easier. They could have been changed out every couple of years to avoid failures.

This collection of Meissner radios also includes a Signal-Shifter EX ( low power CW transmitter ) and a much smaller kit radio. I will post any updates on those as I get to them.

It seems that many radios were sold as kits or replacement chassis for a cabinet that a customer already owned. This is consistent with the company's other offerings of  quality OEM and replacement parts. Some were sold under the name Maguire. You might want to do more research under the name Thordarson-Meissner / Mt. Carmel, Illinois. Thordarson is still in business. (Thanks Ron)

To conclude, this series of radios, especially the large chassis with FM, were very high quality only lacking the chrome to be compared with the very high end radios of the time. If you happen upon one of these radios and have never heard of, or seen one, you are not alone. If the price is right, you might want to add it to your collection.

Nipper-

Time to clean out the parts room. And, what to do with the Victor Micro-synchronous receiver chassis? It was very rough and over the 5 or 6 years it had been there, not very useful. I guess that I had just kept it for the top cover. I had always thought that it would have been nice if the heavy, stamped covers were more visible inside of the RE-XX cabinets,

Well, the chassis is gone but Nipper has been polished and mounted  (that sounds wrong ). I'll set him on top of the "Talking Machine" display.

Probably the best way to add quality programing to your old radio collection is with a low-powered, local transmitter broadcasting personally selected content.

Such devices have become inexpensive and, to some extent, reliable. Issues with these transmitters are usually associated with noise, interference and modulation levels/quality. There are at least two instances where using a Part 95 transmitter is not the best solution.  First, those people with only one or two radios might not want the additional expense and the associated hardware for their small collection/display. More significant for us "serious" collectors is the inherent mediocre audio quality and it's reproduction on a very high end radio like a Scott, McMurdo Silver or any of the high tube count radios of the 1930's to the 1970's. It is difficult to get the performance that these radios are capable of without quality input.

Many of these high-end radios came with phonographs or at least a phonograph input that can be used with modern source equipment. The most significant drawback associated with using your MP3 device as an input is the relatively small signal voltage that they generate for audio output.

The other significant compatibility issue is that even the mightiest, 25 tube (or more) hi-fi system built prior to 1955 was only single channel (mono) reproduction. So even with a quality phono input, the question is  - "So where do I plug-in this other cable". Using a "Y" adaptor that ties your right and left stereo channels together (with no isolation) is usually a bad idea and might even damage some devices.

The simplest solution in many cases is to build a matching transformer/cable using 2 small output transformers. This will provide isolation for the R and L channels of the MP3 device along with a voltage boost - and less than great frequency response. This is still a good choice if you have a phono input or can manufacture one.


What we have here is completely different.

First a little background: Mentioned below - and still lacking the story it deserves - is a collection of radios/chassis/parts donated to the cause in early summer of this year. Among these was a Scott 510. All of the components were there including the cabinet which was the typical, rectangular, late 40's box with a couple of doors - not my favorite design. This cabinet was originally finished in the white-washed color that was popular in the 1950's. Along with the yellow-ish finishes of the same period, also, not a favorite. The overall delaminated, banged up, falling apart condition contributed to the decision to not restore.

The receiver chassis used in the 510 is good, maybe even very good, but certainly not consistent with the quality and leading edge design of earlier Scott models. So, I scrapped that chassis too.

The remaining chassis is the chrome-plated power supply/audio amp seen in the first picture, above.

This is a nice unit using a 6SN7GT driver and push-pull 6L6s for output. And look at the size of that audio-output transformer (8 ohms only). The published frequency response is 30 to 20k hz at +/- 1 db.

http://www.nostalgiaair.org/Resources/592/M0016592.htm

It was built with a dual power supply using both a 5y3GT and a 25Z6GT as rectifiers. The 25Z6 was no longer necessary since it only supplied the receiver chassis. There was also a nice large choke (underside of chassis) that was now no longer needed. Having recapped the unit, I decided that it would be nice to incorporate this choke into the amp's power supply. So I reduced the value of R48 from 375 ohms to about 275 ohms and installed the choke between the first and second filter caps.

Testing the amp using input from my Samsung phone, I found the output to be way too low to be satisfying. There was just not enough voltage out of the phone to drive the 6SN7 grids (in parallel). The extra, now unused rectifier socket was also screaming - "stick a tube here". So I did.

The objective was the same as stated above, to provide isolation, voltage gain and combine (mix) right and left channels. Since I had plenty of power supply overhead - lacking the need to power the receiver chassis, the obvious solution was the addition of a 6SL7gt stage prior to the 6SN7 driver.

So how is this done? Easy. Just look in the index of your RCA tube manual under the chapter on Resistance Coupled amplifiers. WHAT? You don't have a tube manual - don't tell anybody and get one here:

http://bama.edebris.com/manuals/tubesandvalves/

The directions are pretty simple. Pick your B+ voltage and desired characteristics from table 5 (I was using RCA 25 from 1966) and dig out the few additional parts that are needed. The drawing and specs are for a single triode. Your are just going to need to double this up for the 2 triodes in the 6SL7. The plates of both triodes will be tied together and feed the grid of the 6SN7 through a coupling cap also speced in the chart. Note that you could probably use a single cathode resistor/bypass cap, but I used 2, one for each cathode.

Most applications are going to need an additional tube socket and a person could use a 12AX7 but I already had a socket - given that it would probably be better further from the rectifier but that would require another hole and the 6SL7 that I chose had the aquadag coating which resulted in ALLMOST no hum. Rolling a few other tubes into this position resulted in some hum. I might add a shield - or not.

The test results were plenty of gain, good frequency response and little or no noise.

I also upgraded the 6L6s to 6L6GCs so that I could play with higher B+. As it is, B+ is running at about 380V. I added 2 shielded cables with RCA jacks to the back of the chassis. You might want to add a coupling cap of around .01uf to each input to the grids of the 6SL7 to provide some safety for your device should one of the grids fail and crash into the plate resulting in B+ going to your phone/device. Otherwise, isolation is good as is the mixing of right and left channels.