Lately in my quest to make my stereo system more tube based I've been looking for a tuner. I ended up buying a Fisher AM-FM simulcast stereo tuner that looks like a simple project. I bought it because I've read that the AM sections of simulcast tuners tend to have better audio quality than most others.

I plan to add an outboard FM-MPX decoder to the mono FM tuner in the Fisher...I want to go with a tube based unit obviously, I want to spend as little as I can, and I want to get decent performance out of it.

That said there is an RCA RK295B FM-MPX adapter on the bay I'm considering buying. http://www.ebay.com/itm/Vintage-RCA-FM-Multiplex-Unit-w-Power-Supply-LQQK-w-12AX7-/281492697990?pt=Vintage_Electronics_R2&hash=item418a45b386
What I'd like to know is: does anyone here have any opinion on the performance of it relative to other decoders out there, and should I wait for something better to show up?

If I wanted to be really cheap I think I might be able to salvage a hybrid MPX decoder out of a gutted Silvertone tuner chassis I have (although it may be a single board tuner design which could complicate things).

That one on ebay right now looks like it's going to meet yer requirements....
You can always put all the tubes in it, make it work, and sell it for more, if
some other one comes along that you want more than this one....

.

If you can find a Fisher MPX-100 or MPX-200 cheap enough then go for those. they are built like tanks and work well

I wound up buying another one of the same RCA chassis with shipping that was much cheaper (lopped 1/3 off the total price of the other one). I figure if the 12AX7 is good I probably have at least the cost before shipping right there.

I'll keep an eye open for the Fisher units, and if I find a good one, then I'll just re-sell the RCA.

Another source is from gutted consoles. Some had outboard units. i got one from an audiokarma member who posted about a magnavox console amp he was converting and posted some pix that showed the tuner and mpx. chassis in the background. i plan to put it in my Motorola SK-77. Currently Im using a Heathkit unit, but I eventually want to use that with another tube tuner for my stereo. The Heathkit unit sounds good, plus you can find manuals for them.

I use a Scott 335 with my McIntosh MR-55, and they sound great together. Also have two Heathkit AC-11's, and they do a good job with a Dynatuner FM-1, and a Meissner oldie.
Good luck in your quest!! :yes:
Kevin

I have two Sherwood S-2200 tuners that have a 4 inch square covered opening on the chassis all ready with a receptacle for the MPX adapter (audio connex, filament power, B+ ,etc.) No luck finding one:thumbsdn:. Oddly, these Sherwoods have separate tuning for AM with wide and narrow filters, so they may have been used for those AM-FM stereo simulcasts.:scratch2:

I once had an all-tube Harmon Kardon F500x tuner with the optional on-board decoder, which was rare on a 1962 model. I still have the matching sweetheart of an amp (H-K A300), but the tuner given to a friend long ago:sigh:.

I suppose, by the time stereo decoders became integrated as standard on new receivers around 1963, nobody would bother with the mpx decoders to refit the older mono units, especially with solid state taking over.