Ah, the Browning Mark 4A.
So, just exactly why does it take two cabinets? Every Browning base radio before the Mark 4 had a separate transmitter. And they were all true transmitters, each with its own separate AC power cord. You could plug it up and transmit without the receiver. Not sure why you might want to, but there it is.
The Mark 4 was different. The receiver contains the one and only power transformer for this radio. It powers every function in the transmitter. No AC power cord, just the fat 10-conductor cable. Won't do one thing but hold down the desk without the receiver. And without a power transformer in it, the desk might need more ballast than that alone.
And that's the subject of today's annoying bad habit. The way some folks will decide to "clean" the blades on the transmitter's 10-pin plug.
The type 310 Cinch-Jones connector's contacts are made with some sort of shiny electroplating over the brass body of each blade. This is a pretty thin layer. If it is allowed to oxidize in a humid environment, you'll get a haze on the surface that a solvent just won't remove, no matter how hard you scrub. This plug will have to be replaced, you say. That 'haze' is just the metal that used to be so shiny, now converted to an insulating compound. Oxygen and humidity, most likely.
But hope is eternal, and this guy didn't just pull out the sandpaper. Looks as if he used a file.
This exposes the brass base metal of the blade. It will oxidize regularly, and you will find yourself pulling it out to clean again every few weeks or less.
This guy took the other approach. The plug was cutting in and out when you wiggle it, so he plumped up the blade surfaces with some solder.
This wallows out the spring contacts in the receiver socket. Makes the problem worse soon if not right away. The receiver that this got plugged into now has a new socket, as well as the new plug.
But wait, you ask. I have a Mark 4, not a 4A. It has a plug that looks like this.
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This "Molex" connector was a fatal flaw. If yours looks clean and white like this one, it's probably because the transmitter failed before any wear and tear occurred. This connector uses tiny cylindrical pins with a diameter of .063 in. Too small for the current load on the heater and ground pins. The plug heats up, darkens the white plastic, and begins to cut out. This is one basis for the legendary "poof chip" fault in the Mark 4. If the ground connection comes loose, those chips can get their polarity reversed. Even if this occurs for only a tiny fraction of a second while you wiggled the plug, it's long enough to fry one or more chips. And the Mark 4 has a lot of them.
We have had a long-standing policy that no Mark 4 radio goes home fixed with that white-nylon Molex connector still on it. Any radio that's going back on the air gets converted to the larger, flat-bladed "Jones" plug. And socket.
Browning came to their senses, and the last Mark 4 radios built had the Jones plug. And every genuine Mark 4A had this connector.
Nothing lasts forever, and we seem to replace a higher percentage of these Jones plugs than we used to.
But if you look at one of these radios with a chance of buying it, take a close look at this plug. But if the plug looks bad, there's a good chance that the socket where it was plugged in will also have enough wear and tear to merit getting changed out. Shiny, clean contact surfaces are always a good sign for anything that's 40 years old.
73
So, just exactly why does it take two cabinets? Every Browning base radio before the Mark 4 had a separate transmitter. And they were all true transmitters, each with its own separate AC power cord. You could plug it up and transmit without the receiver. Not sure why you might want to, but there it is.
The Mark 4 was different. The receiver contains the one and only power transformer for this radio. It powers every function in the transmitter. No AC power cord, just the fat 10-conductor cable. Won't do one thing but hold down the desk without the receiver. And without a power transformer in it, the desk might need more ballast than that alone.
And that's the subject of today's annoying bad habit. The way some folks will decide to "clean" the blades on the transmitter's 10-pin plug.
The type 310 Cinch-Jones connector's contacts are made with some sort of shiny electroplating over the brass body of each blade. This is a pretty thin layer. If it is allowed to oxidize in a humid environment, you'll get a haze on the surface that a solvent just won't remove, no matter how hard you scrub. This plug will have to be replaced, you say. That 'haze' is just the metal that used to be so shiny, now converted to an insulating compound. Oxygen and humidity, most likely.
But hope is eternal, and this guy didn't just pull out the sandpaper. Looks as if he used a file.
This exposes the brass base metal of the blade. It will oxidize regularly, and you will find yourself pulling it out to clean again every few weeks or less.
This guy took the other approach. The plug was cutting in and out when you wiggle it, so he plumped up the blade surfaces with some solder.
This wallows out the spring contacts in the receiver socket. Makes the problem worse soon if not right away. The receiver that this got plugged into now has a new socket, as well as the new plug.
But wait, you ask. I have a Mark 4, not a 4A. It has a plug that looks like this.
This "Molex" connector was a fatal flaw. If yours looks clean and white like this one, it's probably because the transmitter failed before any wear and tear occurred. This connector uses tiny cylindrical pins with a diameter of .063 in. Too small for the current load on the heater and ground pins. The plug heats up, darkens the white plastic, and begins to cut out. This is one basis for the legendary "poof chip" fault in the Mark 4. If the ground connection comes loose, those chips can get their polarity reversed. Even if this occurs for only a tiny fraction of a second while you wiggled the plug, it's long enough to fry one or more chips. And the Mark 4 has a lot of them.
We have had a long-standing policy that no Mark 4 radio goes home fixed with that white-nylon Molex connector still on it. Any radio that's going back on the air gets converted to the larger, flat-bladed "Jones" plug. And socket.
Browning came to their senses, and the last Mark 4 radios built had the Jones plug. And every genuine Mark 4A had this connector.
Nothing lasts forever, and we seem to replace a higher percentage of these Jones plugs than we used to.
But if you look at one of these radios with a chance of buying it, take a close look at this plug. But if the plug looks bad, there's a good chance that the socket where it was plugged in will also have enough wear and tear to merit getting changed out. Shiny, clean contact surfaces are always a good sign for anything that's 40 years old.
73