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MF-300 & Remote Control Acquired

When I took the cover off of the RK-20 a piece of foam rubber that had turned hard and crumbling with age fell out. I will have to look to see where it was in the receiver. I think I spotted some evidence of an adhesive on one side of the foam. If I can find another surface with the adhesive on it I should be able to see how it was positioned. I believe it was there either to prevent vibration or to keep a part from being jostled about during shipment. There is one physically very large film type capacitor in the back end of the receiver that looks like it could vibrate in shipping to the point that it could develop metal fatigue in its leads. Fortunately this one does not exhibit that sort of fault for now.

Joe
 
I wonder how critical that battery voltage is. Typical lithium is 3.7 volts, or you could stack up 3 1.5v coin cells to get 4.5v. Depending on the sizing you may be able to stack the coin cells in the original slot, maybe with the addition of a spacer to make it fit without mods to the control.
 
I get jealous whenever I look at progress! Maybe I won't hold out for the MF320.

A friend here in my area (who I got my TFM1000 and R200B from) had one of these a while back that he had a local go through - he said the tuning motor set up was pretty entertaining to watch and listen to once it was working.
 
Gadget and Matt;

I doubt that 4.5V would cause any problems with the remote hand unit. That's only about a 14% difference so it should not cause any problem with the functionality of the hand unit. Getting the hand unit operational and checking the power supply portion of the ultrasonic receiver will be first tasks. There is some corrosion on the battery contacts in the hand unit. Those will need to be cleaned. I am thinking a stack of button type cells that can produce 4.5V will be a good approach. They could be stacked together and a piece of heat shrink placed around them and shrunk over the group to hold them together. Where there is a will there is a way.

I need to research and see if Fisher applied for a patent on this remote system. For the receiver to be able to determine which direction the user rotates the hand unit while depressing one of the hand unit buttons would involve some interesting design approaches. Just looking inside the remote receiver I believe it was manufactured in Germany. I need to look closer at the components. My thought is that the transducers in the hand unit and the receiver have to have a way of communicating signal polarity.

The rear connectors with white nylon shells are made by Amp corp. I believe. I need to find a source of male and female shells and contacts so I can make inter-connect cables for connection to/from the tuner chassis. I also need to see how the remote unit is powered. Does its AC cord plug into the tuner's accessory AC socket or do the Amp connectorized cables bring AC power to it?

More later!

Joe
 
Joe; That AMP connector on the right looks suspiciously like a 4 contact connector for most phonographs of the period. You could start there and see. I've seen that 3 pin connector on the left somewhere, but can't remember where tho. Maybe on a console......

A mercury switch could determine direction, which I think I see in the middle of the remote.
 
After a first look at the MF-300 tuner unit here are the things I noticed:

MF 300 First Glance
The MF-300 is Serial Number 10176A. The top of the chassis and the rear apron has very little of the tube ID and V numbers remaining on it. It has been cleaned with something that removed almost all of the lettering.

There is only one 3-conductor cable connector on the back of the MF-300 tuner. There is one AC socket. There are Tune-O-Matic Sensitivity, Right and Left Channel Volume controls on the back of the tuner.

The Front Controls are:
Top Left; Stereo Filter – On Off
Top Right; Tuning

Lower Left; Selector – Mono, Automatic, Stereo
Left Center; Muting – Off, Normal, Max

Center; Tune-O-Matic - <-- -->

Right Center; AFC – Off, Normal, Low
Lower Right; Antenna – AC Off, Normal, Local

Since there is only one 3-conductor cable receptacle on the back of the tuner I conclude it carries only the tune up lead, ground lead and tune down lead coming from either the RK-10 Wired Remote or the RK-20 Ultrasonic Remote. There are Audio In and Audio Out for both Left and Right channels on the RK-20. I believe when the RK-20 is used to control volume that the user is expected to set the MF-300 rear chassis volume controls at maximum and then use the remote to control the volume going to a preamp or integrated amplifier. The volume control inside the RK-20 is a continuously variable control, resistance value unknown at this time.

I connected the tuner to power and turned it on. The dial lights up well and the dial pointer lamp is still good. It appears to be one of the grain-of-wheat type lamps that are very small. I assume it is a 6-8VAC lamp operating from the filament winding of the power transformer. There are two red lamps on the dial face that light continuously when not operating the tune up or down feature. I think one will wink out to indicate tuning direction and then turn back on when the tuning search has finished (TBD).

Joe
 
Larry;

I agree. I looked at the connectors I removed from the 690-T and see that they are the same style, just had more contacts. One question I have is do the male contacts engage with a female contact in the mating connector, or are two male contacts used in each mating connector shell and one just brushes against its mate on one side?

On the rear of the RK-20 remote receiver, there is one male connector shell with 3 male contacts that is to interface with the male connector shell with 3-male contacts on the back of the MF-300 chassis. Both of these would require a female connector shell with contacts inside. The rear of the RK-20 there is one other multi-contact Amp female shell connector which has 4 contacts inside and it states it is for connection to an RK-15 Wired Control. I have not seen anything yet that describes an RK-15. The MF-300 brochure mentions an RK-10 Wire Remote.
MF-300 Front Panel web.jpg MF-300 Chassis web 01.jpg
Do any of you know the Amp series of connectors involved? As Larry mentioned they are the same type and contact size as were used on mating record changers that Fisher used in their console radio-phonographs.

A question about the knobs - all the ones on this unit have no dashes on the knob brights. Is this correct or do they need the knob brights with the dashes except for the tuning knob? Each knob except the tuning knob does have a pointer ridge on the outside molded plastic.

Joe
 
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Joe if the metal connections inside the shell are round it's a female to male. If they have a flat on them then its' a male to male sliding connection like the 49A and 59A speaker connections.

I think the Rk15 is a typo. All of the FISHER remotes I've seen have an ending ZERO on their model #'s

My FM100 has the knobs with the raised pointer on it. No dashes. At this point I'd rather have the dashes on them so I can see what's what. I'd say personal preference now.
 
Larry;

I think you are correct. There does not seem to be an RK-15 and the brochure for the MF-300 only speaks of an RK-10 wired remote. I noticed in a copy of the Fisher 1964 Brochure that the President model was available with the MF-300 and the Wireless Remote so likely a few of those luxurious consoles were sold with that option. They also had a Living Theatre III which also appears to have been offered with a wireless remote that also permitted channel change on the TV section plus on-off and audio level control.

The contacts are definitely flat sided, so they must be the male to male sliding contact type. On this type of connector system, one connector shell has contact compartment divider walls and the mating shell does not. These do tend to be very durable connectors. I may have to remove one contact from the plug I removed from the 690-T chassis to get the dimensions of the contact. That will help me identify the exact model connector shell and contacts used.

The knobs appear to be similar to the ones Fisher began to use on their solid state models, but still having the small ridges on the knob for a good grip. The pointer can be felt, but like you, I like the presence of the dash on the knob bright to indicate the position of the control at a distance.

Joe
 
Here is a tube layout diagram of the MF-300 starting from the layout diagram of the FM-200-B tuner which is very similar with changes and additions.
MF-300 Tube Layout.jpg
Joe
 
Sooooo, V13 is now a single triode tube as the muting oscillator....

V9 must be the receiver for the remote.......

V10 must be the Stereo Beacon and Motor control?

Dave
 
Dave;

I think you are correct about V13. V10 may be as you suggest, I am not sure at this time. I have some service information on the MF-300 coming from a fellow member of the FM Tuner Group of Yahoo. As soon as I get that I can verify the function of the various tubes better. My understanding so far is that V9 is part of a detector for the motor driven tuning so that it stops at the right time as it reaches a good signal.

I have a discussion going with a friend in SF about this unit and both of us are wondering what happened to the Fisher documentation of older products after Avery Fisher sold his company to Emerson and successors? Did the documents get thrown away?

Joe
 
No. Best understanding is that they were burned in a fire in a warehouse in California connected with the the company that bought Fisher from Avery. Ping Larry. He will know far more than me about it.

Dave
 
Hi Joe. Congratulations! I'm happy to see you got him to split them up. Very nice units. It will be interesting to read your comments on the tuner and remote.
The MF 300 I use daily came out of a 1963 President console. The console included the RK20. The only difference I've noticed between it and my other RK20 is the lettering on the face plate. Looks like Fisher did that with most items in the President console. Also the hand held has different colored graphics.
 
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You are right that it is a simple 3 wire plug that goes between them.
My 1st remote was working when I bought it but the battery was dead after the hand held unit sat for a couple years unused. The Person In Denmark I bought my first remote from had put a self made battery into it. It looked like he used several small watch type batteries attached together. Once the battery was dead, and since I rarely used the remote I didn't look into what would work so it will be nice to see what you come up with.

RK20 Remotes.jpg
 
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Joe, from your photos it looks like your RK20 was sold as an accessory to the MF300 and not from a President console. The console version has different lettering on the face and the hand held remote has red where yours is brown in color. I'll dig out the 2 remotes and add photos.

President RK-20

Pres RK20.jpg

I have manuals for the four wire RK-15 wire remote control adapter, MF300 standard and President version, the RK-20 and other accessories somewhere in my files.
RK-15.jpg

The RK-15 looks exactly like a red hand held but with a very,very long cable attached.
 
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Well, I'll be a sumbitch! The RK-15 Exists!

Joe; My understanding is that after Sanyo took over in 1975 or so all of FISHER was moved to Chatsworth Ca., with the old paperwork (manuals and production sheets, etc) going to a warehouse in Northridge. In1979 during the Earthquake, it appears that everything was watersoaked by sprinkler system or otherwise destroyed and was subsequently dumpstered.

Larry
 
Vendo81;

Thanks for that extra information. I see from the two open RK-20 receivers that the foam rubber pad that fell out of mine was used on the top of the transformer at the rear. It was probably there to combat some 60Hz vibration. Now I know where to put new padding. I notice that the connector on the back for the RK-15 has four wires. If you have time to copy the manuals or send scanned versions of them I would appreciate it. Every bit of documentation is precious on such rare items.

Larry;

Thanks for sharing that information about the fate of the older Fisher documentation. This group has done a good job of reconstructing a library of documents on the older equipment. I hope more people will contribute scanned images of manuals for items that we do not already have in the AudioKarma Fisher database.

Joe
 
Between the AK Database and the Fisherconsoles site, I think we might have 85% of 1958 to 1967 or so covered one way or the other. There's still some missing, but we're getting there.
 
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