The Statesman (202-T) Wide-Band AM-FM Multiplex Tuner Preamp

Discussion in 'Fisher' started by dcgillespie, Jul 21, 2017.

  1. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    THE FISHER MPX-50 SUB-CHASSIS

    A big thanks to AKer Vendo81 for sending me the (truly) rarely seen MPX-50 sub-chassis that came with his 100-T tuner/preamp for analysis! This is the unit that was without a doubt specifically designed -- even if it was at the 11th hour -- to be retro-fitted (retro-fitted because the units themselves were never designed for this type of sub-chassis) into the Crosby designed Fisher units that were initially offered with a blank plate, awaiting the final FCC decision as to format and commencement date. In all of my years, this is the only MPX-50 unit I've ever seen even in pics, let alone physically on the bench. They must truly be one of, if not the rarest of Fisher items produced.

    Like all of Fisher's MPX sub-chassis units, the MPX-50 also operates on the time division principle. And while the design of the unit is very similar to the more common sub-chassis units, it is also notably different in one important aspect.

    At issue is how Fisher engineered the sub-chassis to revert to true mono operation (L+R signals out of both channels of the adapter), since once the adapter was installed, Channel A was then permanently receiving the Channel A output of the adapter for any FM setting of any type on the Input Selector switch. Being able to receive any FM station in mono mode is important both back in the day and today, since all stations did not immediately converted to FM Stereo MPX operation once the decision was handed down, and being able to listen to noisy MPX broadcasts in mono is desirable when the noise becomes excessive. As well, there are still a number of news/sports/talk stations today that broadcast in mono to increase their reach.

    Allowing FM mono stations to play through the typical Fisher MPX sub-chassis allows the ring demodulators to try and work backwards and become modulators during that time, which produces distortion in the output. The answer Fisher adopted for this is to select the adaptor for stereo stations only, while selecting the output of the mono de-emphasis network that is sourced right off the ratio detector transformer to listen to mono stations. This is how all Fisher Wide-Band units are designed. Sometimes the switching is done automatically, sometimes it must be done manually, but the capability is there for that reason. In the Crosby based tuner/preamps however, there's no automatic function, and the selector switch doesn't allow for such switching, so the adapter itself much be electronically switched between stereo and mono operation -- and done so with no more than the grounding (or not) of a single switch terminal on the Input Selector switch, based on its setting. Since I indicated that there was just no good way to do that with the typical Fisher sub-chassis, it was of interest to find out just how in fact they dealt with this issue. If there was some easy way to modify the typical adapters to achieve the required switching that I wasn't aware of, without the need for (at least) an audio control relay, I was certainly interested in finding out what it was.

    First up then, are the similarities between the MPX-50, and the other Fisher sub-chassis units:

    1.The MPX-50 employs two 12AT7 and one 12AX7 tubes, just like the WX sub-chassis does.

    2. The MPX-50 employs the same 19 kHz and 38 kHz transformers as to Fisher's other sub-chassis units.

    3. The tubes in the MPX-50 all perform the same basic functions as they do in the other sub-chassis units, with only very minor alterations in some of the parts values associated with the tubes.

    4. The alignment instructions would be the same between the MPX-50, and the other Fisher sub-chassis units.

    5. The MPX-50 is the same physical size and structure as the other sub-chassis units.

    So what are the differences?

    1. There is no indicator output on the MPX-50, which is as would be expected, since there is no provisions for a stereo indicator on either of the stereo tuner/preamp offerings.

    2. The MPX-50 requires only one source of B+, about 185 vdc. The other source of the commonly seen dual B+ requirement for the other sub-chassis units is not used in this unit.

    3. The de-emphasis tailoring is split up into two separate parts of the signal path, with one network before the matrix output stage, and the customary networks similar to those seen after the matrix stage in the other sub-chassis units.

    4. The big one is -- relative to the question of this discussion -- that the beauty and symmetry of the dual balanced 38 kHz ring demodulators -- as used in Fisher's other sub-chassis units -- is scrapped for two single diodes -- one to demodulate the L-R, and the other the -L+R signals accordingly. Additionally, since no coupling caps are used coming of off the 38 kHz oscillator, these two diodes (after appropriate isolating resistors) see B+ voltage levels applied to their anodes, and therefore have their cathodes returned to B+ as well for AC ground, rather than actual ground as is typical of the other sub-chassis units. The result of this configuration is that if a 470K resistor is connected between the output side of the 1 uF composite signal coupling cap and ground, then the two diodes become back biased and cease to conduct. Without any conduction there can be no demodulation of any 38 kHz signals present, meaning that the outputs will only contain L+R information or FM mono signals, regardless of the type of broadcast received. And because the voltage source is great enough that produces the back bias for the diodes, the L+R audio signal that is present is not strong enough to cause the demodulators to attempt modulation, so the mono audio output is clean. It's definitely a neat little solution -- but of course one that required a complete redesign of the demodulator section.

    So which approach is best? I plan to power up this unit to give Vendo a status report on it so he'll know how to proceed with it when restoration time comes. Typically however, the best separation numbers that most dual diode designs can approach is about 30 db, which is short of what the elegant balanced approach of the other sub-chassis can produce. To be fair however, whether you can hear that difference or not is certainly debatable. That would suggest that if you have an MPX-50 for a Crosby unit, it should certainly perform well. On the other hand, if you don't have an MPX-50, or you want the best possible performance, then it's doubtful that an MPX-50 -- even if you could find one -- will match the excellent performance that the WX chassis can produce in a tuner setting.

    That leaves two last points to touch on:

    1. The design of the MPX-50 is so similar to the other sub-chassis units when it comes to the design's frequency and phase response, that no doubt an MPX-50 would also benefit from the installation of the later ratio detector transformer. However, this has not been tested. I do not have any units here using the older RD transformer, but the MPX-50 can certainly be tested on a unit that has the newer transformer installed, and therefore compared to the performance of a WX sub-chassis that way. I hope to get to that in the next few days.

    2. Fisher clearly decided to punt on the idea of modifying the eye tube circuit so that it could also act as a stereo indicator, so the action of the eye tube does not change in either of these units when a MPX-50 is installed.

    More as the info is generated. No pics this time, since Vendo has already provided pics of the unit he sent.

    Dave
     
    Last edited: Jul 30, 2017
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  2. vendo81

    vendo81 AK Subscriber Subscriber

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    Very interesting Dave and thanks for the write up! Looking forward to your test results.

    This MPX-50 actually came out of my 202-T. My 100-T has a MPX-65 installed. The manual I have shows the MPX-50 installation instructions for the 100-T, 202-T and the FM-100 tuner and specific instructions on operation once installed.
     
  3. vendo81

    vendo81 AK Subscriber Subscriber

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    That's great info Larry. I have several post 1962 console tuner/preamp combos so I'll remove what I need.
     
  4. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Thanks for the correction, Vendo. Any data as to how well this unit performs however is going to have to wait, as this sucker don't work. The tubes I installed all light up and draw appropriate B+ current, and the 38 kHz oscillator even puts out a healthy signal as well, but it won't lock onto the MPX pilot signal to save itself. Therefore, no L R separation. The coupling caps aren't leaking either, so something is clearly amiss. The 1 uF composite coupling cap is intermittent and certainly needs to be replaced, but that wouldn't impact the the no-trigger condition being displayed.

    So, a little detective work is in order. Hopefully, I will be able to start on that tonight........

    Dave
     
  5. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    OK then. Three bad components combined with someone trying to fiddle with the adapter's alignment to make it work in spite of the bad components will virtually always guarantee an adapter that won't work under any circumstances. Such was the case at hand. Bad components included:

    1. The 1 uF composite signal cap was intermittent, with a very high power factor.

    2. The Left Channel output coupling cap was also intermittent, which if these types of caps are going to fail, this is how they will. Rarely if ever do they leak any DC through them. They just go intermittent, which can be triggered by simply tapping them with a pencil.......

    3. The 20 uF 250 volt cap housed in the mini electrolytic can measured 32 uF on conventional cap testing equipment. But when the same test is conducted at 50 kHz on the cap, it measured open, which lead to all manner of strange problems noted.

    The resulting alignment was further out than simply left field -- it wasn't even near the ball park.

    So, with the 1 uF composite cap and .047 Left Channel output coupling cap replaced, and a 10 uF 450 volt cap I had handy tacked in across the mini can cap to effect its replacement, an alignment could be performed in normal fashion, producing results that are typical of dual demodulator diode designs. A series of pics will show this best:

    BELOW: Except for the can cap, the defective components have been removed, and new ones installed. The cap temporarily tacked in placed replaces the mini can cap uniquely used with this model sub-chassis. An alignment could then be performed uneventfully.
    SAM_2176.JPG
    BELOW: All connected up for alignment and testing. You can see the new composite and output coupling caps installed as well.
    SAM_2168.JPG
    BELOW: Separation R to L was 29 db, but with a notable amount of 38 kHz sub-carrier energy leaking through the unbalanced demodulator circuits, particularly in the Left Channel, represented by the line through the middle of the waveform.
    SAM_2171.JPG
    BELOW: Separation L to R was 27 db, now with the right Channel representing the line through the middle of the waveform.
    SAM_2172.JPG
    BELOW: Finally, what this whole exercise is about. The designated terminal is grounded, resulting in balanced mono operation from each channel's output, as evidenced by the absence of the center line. Both channels now display the same output, with the waveform of one channel appearing on top of the other in this view. Note however, the baggage that comes along for the ride. In my earlier musings, I had thought that the demodulator diodes might be able to kill most of the residual 38 kHz energy when they were reversed biased in mono operation -- but the balance of the circuit is such as to still allow some energy to leak through as can be seen. This is the very concern I had with trying to trigger a conventional WX and MPX-65 sub-chassis into a mono mode of operation, and clearly the reason that Fisher chose to take the mono audio from its own de-emphasis network connected right to the ratio detector transformer. The FM mono audio is as clean as it gets at that point.
    SAM_2174.JPG
    BELOW. Testing is complete, with the mysteries of Fisher's Crosby hiccup finally sorted out. The MPX-50 certainly served a purpose for those three Crosby based models that slipped through before production was halted (Statesman/202-T, Coronet/100-T, FM-100), but compromises were surely made to do it. If you compare the separation performance pics of this adapter -- which is being driven directly by the MPX generator (always an ideal scenario) -- to those produced by the modified Wideband Statesman/202-T of this thread posted earlier -- in which the signal are broadcast into that unit -- the improved performance of the WX chassis is obvious. The MPX-50 sub-chassis can certainly fill a need, but I would suggest that for the best performance, the extra effort of installing a WX sub-chassis in a Crosby based unit is well worth it.
    SAM_2175.JPG

    Dave
     
    Last edited: Jul 31, 2017
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  6. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    The MPX-50 was apparently FISHER's 1st attempt at internal GE/ZENITH type MPX boards as I can't find anything earlier for this type and style of MPX. So rather than wait until they built a MPX unit that would demodulate the signals at 35db or better (WX and later)without the 38mHz hash, Fisher came out with the MPX 50 as a stop-gap measure. As it apparently lasted only 1 year or less Vendo's got a very rare gem.

    Very nice job Dave. It boggles the mind, the stuff that goes on in your lab, which directly helps us understand and keep these old girls running.

    Larry
     
  7. gadget73

    gadget73 junk junkie Subscriber

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    Been there, done that. Gotta love it when the "fix" just causes more work than if it had been diagnosed correctly the first time. I don't know why people love to turn screws, but wow does it mess things up.
     
  8. vendo81

    vendo81 AK Subscriber Subscriber

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    Great job Dave! Your skills along with your lab is first rate :beerchug: Must have been fascinating times back when FM went through the choice for a stereo decoder...but hectic for the engineers of the time. The MPX-50, although not perfect, surely fit the need for the 3 units mentioned. This out of the way gave the Fisher engineers time to design a proper MPX unit, and to add correct changes into the tuner designs to work as they should.

    When I get the chance to rebuild the 202-T it's great to know the MPX-50 will be plug and play :) Thank you for your work!
     
  9. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Thanks Larry -- After close scrutiny, it appears that there is a serial number on the unit -- which makes sense, since it was almost surely produced as a separate item for sale and never installed in anything at the factory. Serial number 10836A, with the "10" appearing to be part of the original silk screening on the unit, and the "836A" being ink stamped on separately at a later time. Like the 1800, could they have possibly made a single run of 1000 units and then called it quits? To use your term, these things are rarer than hens teeth.........way, way rarer. With the number of 1800s that have ultimately turned up (at Steve's house anyway), you'd think that if there was a run of 1000 made of these, then there'd be more of these critters out there. Of course, they had to sell to be out there. Who knows, maybe the excess was just tossed in the dumpster at some point in time........

    Dave
     
  10. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    MPX-50 EPILOGUE

    The last little detail to chase down was the fact that while the Fisher alignment procedures for the WX and MPX-65 sub-chassis can largely be used as written for the MPX-50 (requiring only minor detail changes), the question remained as to whether the unit -- once so aligned -- would be closely aligned to the optimum separation control setting as would be required when installed and operating in a non Wide Band tuner. That is, when bench aligning a WX or MPX-65 (i.e., driving them directly from the MPX generator) according to the published instructions for those sub-chassis, the separation control will then be very nearly if not at an optimum setting for any Fisher Wide-Band tuner or receiver after installation -- provided of course that the basic tuner section is correctly aligned as well. So the question is, would the MPX-50 so aligned then also result in its Separation Control being very nearly at an optimum setting for a non Wide-Band tuner installation? Theory says it would not be.

    The Separation control is actually controlling the amount of L-R information that appears in the L and R stereo channels, as having precisely the right amount produces maximum separation between the channels. In the FM Stereo MPX signal broadcast by the station, the L-R information exists in the band of frequencies between 23 kHz and 53kHz. In Wide-Band equipment, these frequencies pass through the Ratio Detector stage basically un-attenuated, which typically results in the optimum setting of the MPX separation control in WX or MPX-65 decoders being set in the classic 5:00 to 7:00 range (based on the control stop being located at 12:00).

    In non Wide-Band equipment however, HF response though the Ratio Detector stage is more restricted, resulting in some attenuation of the L-R information. In theory then, in a non wide-Band tuner, the optimum setting of the separation control would be one that allows for more L-R information to appear so as to re-establish a proper matrix balance, since less L-R information is getting through the Ratio Detector to begin with.

    To see if this fact holds true, I connected the aligned MPX-50 to a non-Wide Band tuner, so that its bench aligned Separation Control setting could be checked with broadcast MPX signals. I don't have any Fisher non Wide-Band equipment here to check it with, but I do have a venerable Eico HFT-90 tuner. This tuner had been freshly aligned, and operates perfectly. It has the requisite Multiplex output jack, and being offered during the same time as Fisher's non Wide-Band gear was (i.e., pre- FM Stereo MPX), it was marketed as a "Broad-Band" FM tuner that was multiplex ready, which is an equally appropriate description of Fisher's non Wide Band gear as well.

    With this tuner, it was found that the optimum setting for the MPX-50's Separation Control came in at a 3:00 setting, which is a setting that would in fact favor much more L-R information being added to the individual channel outputs. Previously, when aligned using Fisher bench alignment procedures, the optimum setting of this control came in within the classic adjustment range at a 5:30 setting. As a double check, I broke out my Scott 335 self powered MPX adapter, finding that it too -- when connected to the Eico Broad Band tuner -- had an optimum separation control setting that would indicate notably more L-R information being added to each channel's output, versus that control's setting on these two adapters when optimum performance was achieved while being driven either directly by the MPX generator, or when connected to a Wide-Band tuner.

    The bottom line of what this exercise shows then, is that while the Fisher bench alignment procedures produce a Separation Control setting that is very nearly ideal when any of their adapters are then installed into/used with a Wide-Band tuner, they do not result in an optimum Separation Control setting for the adapter when installed into a non Wide-Band tuner. And this is what concerned me. Therefore, after bench alignment, the final Separation Control setting for any adapter installed in/used with any non Wide-Band equipment must be established by broadcasting multiplex test signals into the actual tuner being used. Fisher procedures have you do this when aligning their Wide-Band band equipment as well. But in that case, any touch-up of the Separation Control's setting -- if even required -- is literally just that, a very slight touch-up. When used with non-Wide Band equipment however, the optimum setting of this control is distinctly different from that which a straight bench alignment produces, making the setting by broadcast test signals mandatory. In the case of Vendo's MPX-50 then, by using the Eico Broad-Band tuner to drive the adapter and determine the optimum installed Separation Control setting, the adaptor should then be as close to plug and play for re-installation into his 202-T as possible when he gets it back. Of course, if he converts his 202-T to Wide-Band performance, all of this becomes moot, and the 5:30 setting becomes optimum again for his particular adapter.

    We'll wrap all of this up in the final post.

    Dave
     

    Attached Files:

  11. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    In pondering all of this, the conclusions drawn include:

    1. All GE/Zenith based MPX adapters of any type, from any manufacturer, require Wide-Band tuner performance for optimum stereo performance, because that's what the GE/Zenith system inherently requires to deliver that level of performance.

    2. Virtually any vintage tuner/receiver of quality offered as a Wide-Band design then will invariably include its own internal MPX adapter, since it is the Wide-Band operation/designation that supports optimum stereo performance from the approved FM Stereo MPX system.

    3. It is safe to assume that virtually all add-on, add-later, out-board, stand-alone type adapters (i.e, any adapter that is not built into a tuner/receiver at the time it is manufactured) are necessarily working with non Wide-Band tuners, because it's highly doubtful that anybody produced a Wide-Band mono FM tuner -- even those that include a multiplex output jack. Why would they? There was simply no need to manufacture one with the response requirements that the GE/Zenith system had until that system was finally approved. As offered in #2, when Wide-Band tuners were produced, they invariably included a built-in MPX adapter.

    4. The stereo performance from virtually any tuner requiring the use of an outboard/add-on/add-later/etc MPX adapter then will invariably be compromised compared to that of a Wide-Band tuner with factory MPX circuitry built in.

    5. Because of the inherent disadvantage that a tuner requiring the use of an outboard (etc) MPX adapter starts out with then, it is important that the Separation Control of the adapter be set when the particular tuner/adapter combo are set up as a pair, this to maximize all available performance. If an outboard MPX adapter is only bench aligned and not had its final adjustment made while operating in or with the set it is operating with, it's performance will be further disadvantaged on top of the basic disadvantage of not being used with a Wide-Band tuner in the first place. These potential double whammy disadvantages make the accuracy of the Separation Control setting in such scenarios more crucial than in Wide-Band units with factory built-in MPX circuits, as any deviation from the optimum setting causes stereo performance to fall off sharply. Best possible performance with a non Wide-Band tuner/outboard adapter combination seems to approach ~24 db of separation. That being said however, while this level of separation is well off the mark of that which a Wide-Band tuner/adapter can produce, a non wide-Band tuner/adapter combo that achieves this level of separation still delivers satisfying stereo sound, so their restoration is still a very worthwhile goal.

    With that, a few final pics to close the thread out........

    BELOW: The HH Scott 335 MPX adapter and Eico HFT-90 tuner used to double check the behavior of the MPX-50, and to mimic the non Wide-Band characteristics of the Ratio Detector transformer in the 202-T. The Eico was my maternal grandfather's that he purchased new as a factory built unit in 1960. The toggle switch he added allowed him to turn his system on or off when he wanted to play records without turning on the tuner.
    View attachment 978538
    BELOW: For reference, the performance of the 335 when receiving a L only multiplex signal broadcast to the Eico. The 335's Separation Control has been set to the optimum setting for use with this tuner. In this pic, the sub-channel filter of the 335 has been turned on to clean up a small amount of 38 kHz artifacts that remains in the resulting audio when the filter is turned off. Separation is about 24.5 db, and audible stereo performance is enjoyable. All scope shots depict a L only display.
    View attachment 978544
    BELOW: A classic setting of the Stereo Separation Control (about 5:30), as shown on the WX sub-chassis of my 202-T after it was converted to Wide-Band operation. The separation performance it displayed was shown earlier in this thread.
    View attachment 978549
    BELOW: The final setting of the Stereo Separation Control on the MPX-50, when connected to the Eico tuner and set for optimum performance.
    View attachment 978554
    BELOW: Which produced this separation performance. Note that other than the 38 kHz artifacts that appear in the output, the separation performance of the MPX-50 is not all that different from that of the 335 -- which is a fully balanced dual ring diode demodulator design. The biggest advantage of the fully balanced demodulator design then is not so much in the separation performance it produces, as it is in eliminating 38 kHz junk in the output. To be fair, the MPX-50 would not display this much junk when installed in one of the units it was intended for, as the shielded cabling within the unit would act to attenuate some of the 38 kHz artifacts. Separation is just shy of 24.0 db, and audible stereo performance is enjoyable.
    View attachment 978556
    BELOW: To show how important it is to set the Separation Control on outboard adapters when connected to the non Wide Band tuner it is to operate with, here is the performance of the MPX-50 when connected to the Eico tuner, after the MPX-50 has had a bench alignment only. Separation is just under 10 db, with it very hard to tell if there is any audible separation at all.
    View attachment 978564
    BELOW: Conversely, if the MPX-50's Separation Control is optimized for use with the Eico tuner, and then bench checked (directly driven from the generator) for proper operation, it sure looks like it needs adjustment to me! Separation is 10 db.
    View attachment 978570

    But it doesn't need adjustment at all. What you're seeing between the last two pics versus the first pic in the three pic scope sequence is the effects of the L-R sidebands passing through a non Wide-Band ratio detector transformer, and how much the Separation Control needs to be adjusted away from the absolute ideal setting to account for the transformer loss, and produce the first (optimized) pic of the sequence. To be fair, there is still some loss of the stereo sideband information even when passing through a Wide-Band ratio detector transformer. But it is greatly reduced from that produced by a non Wide-Band transformer, to the point that it allowed Fisher to use a simple R/C coupling network between the generator and their WX, MPX-65, etc sub-chassis, that would then allow a bench alignment of the Separation Control to closely mimic that required when installed in a set.

    With that, this horse is just about beat to death. But Fisher FM Stereo MPX performance is so darn good when it's right, that it's a shame when it's not right. For those going after the pre-FM Stereo MPX Fisher gear then, you've got two choices: Make the best of its non Wide-Band stereo performance as just discussed, or convert to Wide-Band performance for the best stereo presentation.

    Happy multiplexing!

    Dave

    Edit: Oops. If you cut the text in half to accommodate size, for some reason the pics don't follow properly. Oh well. If you look at the pics from left to right, top to bottom, they will follow the text in this post. Or, just click on the attachment and you can see them that way, too.
     
    Last edited: Aug 3, 2017
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  12. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

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    Great thread Dave and bet your glad now I mentioned this tuner 5 weeks ago. great learning experience for us all.
     
  13. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Absolutely! What amazes me is that for a unit that had a service manual that went to the top of the 30000 range, you just don't see that many of them. Besides mine, I know of only two others -- both owned by AKers. One is up in the NE (I believe) that I worked on, and the other is Vendo's that this MPX-50 came from. Oh, and I think I saw one once on the auction site. I'm sure there are others -- but none I'm aware of.........

    Dave
     
  14. vendo81

    vendo81 AK Subscriber Subscriber

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    Not a lot of them out there Dave. I watch the auction site and haven't seen one for quite some time. Just service manuals and an occasional brochure. I did see one locally on craigslist a few weeks ago in the Central California area but it had sold very quickly the first day. They really are a special pre/tuner.
     
  15. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Thanks Vendo -- coming from you, that really confirms my suspicions -- as in, not a lot out there. So the question is, where did they all go? I would surely hate to think that they were simply trashed due to being a Crosby intended unit....... Fisher has a fairly long running tuner/pre line during the mono years I believe, but other than the Coronet/100-T and Statesman/202-T that was it for the stereo years, and both rather short lived with the wrong stereo MPX format at that. Could you just imagine -- what if they had gone on to make a tuner/pre made up of an R-200/400CX-2 combo in limited quantities as well? No telling what that would be worth today!!

    Dave
     
  16. vendo81

    vendo81 AK Subscriber Subscriber

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    My only guess as to why there's not a lot of 202-T pre/tuners out there would be the original asking price compared to the 100-T that was produced at the same time. I have a mail order catalog around here somewhere and noticed a photo and write up on the 100-T, but just a listing of the 202-T with no photo and very brief description. I'd think if you invested in a 202-T you would surely buy the MPX-50 but you just don't see them in any examples found.
    Dave, I hope you realize how fortunate you are to have such a nice example of a 202-T. It's not common and such an exceptional preamp and tuner combo. Your restoration expertise and MPX upgrade give you a true one of a kind collectors item. I personally find this era as being the best looking Fisher's as well.
    Yes a R-200/400cx2 would really be something! I really like my R-200 as I do listen to AM on a regular basis. My tuner tech/good friend has had every Fisher made but chose the R-200 as his keeper when he sold most of his collection off.
    I've been reading on the TFM1000 and it looks like a great solid state tuner. I've passed on a couple of those locally, mostly because they are solid state and didn't work but now will pick one up when I see one.
     
    Last edited: Aug 4, 2017
  17. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Understand, but again, the service manuals indicate that the 202-T was in fact manufactured into the 30000 range. Where'd they all go? Heck we know of more 1800 receivers than we do 202-Ts, and by all indications, they only made 1000 (if that) of those!!

    I am very aware that the 202-T I got was my Fisher "find" that we all hope to have. I'm so appreciative to Al for making me aware of it. I had mentioned to him some time ago about the 202-T I had worked on some years ago and how neat I thought it was. He was looking for a preamp only and found the 202-T; mentioning it to me in considering it for his own needs. After discussion, he graciously gave me permission to pursue it, which took no thought at all. He then found a neat little Hafler type preamp that suit his needs perfectly. A real win-win. Now if Mac would only get the glass manufactured for his tuner/pre that the shipper broke. What a sad story that was........

    Dave
     
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  18. vendo81

    vendo81 AK Subscriber Subscriber

    Messages:
    1,495
    Location:
    California
    The fact that they were manufactured up into the 30,000 range is a real mystery as I just can't see people throwing loads of these out :dunno:
    They really are scarce while the Cornet/101-T is fairly common. Most 101-T models I see were from consoles. I wonder how many Statesman consoles were sold that year. Mine is a stand alone unit so they weren't just put in consoles.
     
    Last edited: Aug 4, 2017
  19. Westy56

    Westy56 A symphony of paradox

    Messages:
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    Location:
    Abq, NM
    Here's a couple with the console that one came out of. :thumbsup:

    [​IMG]
     
  20. vendo81

    vendo81 AK Subscriber Subscriber

    Messages:
    1,495
    Location:
    California
    I do remember seeing these. I wasn't sure if they were 100-T's or 202-T's. Very nice :thumbsup:
     

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