DO I JUST GIVE UP????

[raider]

I have read and read and read some more about trying to find a vfo to work with the Mark II browning. I thought I had the right Maco 10A but it turned out that the yellow wire was for ground when activated. Was told this one would not work. I have heard of new buffers, expanders, sliders and the old adaptor for the glen...what I still do not know is if I will ever get something that will work. Any ideas, including just forgetting about it? I have tried to buy one from Alan (out of stock for the last two years).........

[2600]

Ahh, there is a "dodge" to make the "Ground to activate" version work on a Browning transmitter. The one you have was probably meant for a Tram Titan II or similar radio. That's how the transmitter tubes are wired in that radio.

The Browning uses a different method. The relay in a Browning AM transmitter switches the "hot" side of the power supply to activate the transmitter. Likewise, the Spot button is wired in the hot side of the tubes' power supply.

What we have done is to take a couple of resistors and a small PN2222 transistor, mounted behind a RCA socket added to the transmitter's rear panel. The yellow wire then gets a phono plug put on it and plugs into the new socket. When the Spot or Mike is pushed, the transistor turns on the yellow wire to ground.

While we're on the subject, did you see if the slider has good output? It has a couple of tuning adjustments inside that get "peaked" for max output. If some dip-stick just randomly cranks the slugs, this can affect the output level.

Bad news is that I'm stepping out of town for better than a week. It shouldn't be that tough to write up the details for this fix, but it won't be until I get back home later this month.

Just consider what else in this transmitter may also need to be addressed before you can make it a "daily driver". The relay is a wear-and-tear item. The electrolytic capacitors will all have to go unless they have been replaced recently.

A clean unit will be less trouble than one that was kept in an unheated space where condensation can form on metal surfaces. Cool nights and warm, humid days will expose a radio to enough moisture to (cumulatively) fill a bucket after 5 or 10 years.

You wouldn't just toss that transmitter into a bucket of water, but ten years in a garage or attic can have the same effect in the long run. A layer of oxide on the spring contacts inside the tube sockes can be frustrating to clean up effectively.

But yeah, this trick works for the "ground to activate" version of the slider. Here's hoping that the rubber dial-drive grommet on the shaft of the tuning knob has not gone bad.

I'll check back in here when I get back home.

73

[2600]

Oops. Didn't make it out onto the road tonight.

So, I'm at home with no diagrams to work with, but maybe I can describe the hookup well enough that someone who can read the schematic will get the picture. Worth a try.

First, a male phono plug goes onto the yellow keying wire. Just the center pin. Some of these sliders were sold with a phono socket on the rear, and some had a coax cable coming out the rear panel. The slider's RF output needs both the center wire and the shield ground connection to the transmitter.

So long as the coax shield gets grounded to the chassis of the transmitter, this is all the ground connection it will need. Whether you put a second socket on the transmitter's rear panel for the coax, or whether you just solder it to the radio, this provides the ground connection for the keying wire. The coax center conductor goes to the "hot" pin of the crystal socket for the crystal you pulled out. It's better to solder the coax center wire to the actual switch lug for that socket than it is to solder to the crystal socket itself. Got a picture of that somewhere. But not here at home.

Just make sure that the outer skirt on any RCA plug you use for the coax has not spread outwards. Squeezing the outer rim of it so that it gets a good ground may be necessary if that plug has been pushed and pulled a lot of times. That skirt is the ground connection, and odd stuff will happen if it is loose, or if the socket's outer surface is not clean and shiny. A RCA socket with a surface that's dirty or oxidized won't give you a good ground connection.

A small disc capacitor, like a .01 uf goes from the center pin of the"keying" jack to ground. Any voltage rating 25 or above is fine. The .01uf value is not critical, either. About any value from .001 to 0.1 uf or in between will work about equally well. The panel socket usually comes with a ground lug that goes on the inside, under the socket's nut. A PN2222 or equivalent generic NPN transistor gets the emitter lead soldered to this ground, and its collector lead soldered to the center pin. A 10k 1/4W. resistor goes from the transistor's base lead to ground. The last part needed is 2 Watt resistor. If memory serves, a value of 100k is right. One end of this resistor goes to the base of the NPN transistor. The other end goes to one of the two lugs on the oscillator tube's tuneable coil. No, it won't reach. You'll need to splice a wire onto the 100k 2W part to reach the oscillator coil. What you want is called the "cold" lug on this coil. It has a fat 22k (I think) 2-Watt resistor on it, and a disc capcitor going to ground. The "hot" lug on this coil is the one you want to leave alone. That one has a bare wire directly to one pin on the adjacent tube socket. The end of the 100k resistor goes to the "cold" side, with the (factory) 22k resistor and disc cap to ground already on it.

Now, when the Spot is pushed, or the mike gets keyed, the NPN transistor will provide a ground connnection to the yellow wire.

A diagram would have been easier, but this will have to do for the moment. Anyone who can read the schematic of the transmitter should be able to make sense of this hookup, I hope.

Best of luck and 73

[masterplanner]

Mar 18, 2022 20:14:37 GMT -5 masterplanner said:

Jul 13, 2008 1:23:59 GMT -5 2600 said:

Oops. Didn't make it out onto the road tonight.


Will this work on a bb30? Thanks


So, I'm at home with no diagrams to work with, but maybe I can describe the hookup well enough that someone who can read the schematic will get the picture. Worth a try.

First, a male phono plug goes onto the yellow keying wire. Just the center pin. Some of these sliders were sold with a phono socket on the rear, and some had a coax cable coming out the rear panel. The slider's RF output needs both the center wire and the shield ground connection to the transmitter.

So long as the coax shield gets grounded to the chassis of the transmitter, this is all the ground connection it will need. Whether you put a second socket on the transmitter's rear panel for the coax, or whether you just solder it to the radio, this provides the ground connection for the keying wire. The coax center conductor goes to the "hot" pin of the crystal socket for the crystal you pulled out. It's better to solder the coax center wire to the actual switch lug for that socket than it is to solder to the crystal socket itself. Got a picture of that somewhere. But not here at home.

Just make sure that the outer skirt on any RCA plug you use for the coax has not spread outwards. Squeezing the outer rim of it so that it gets a good ground may be necessary if that plug has been pushed and pulled a lot of times. That skirt is the ground connection, and odd stuff will happen if it is loose, or if the socket's outer surface is not clean and shiny. A RCA socket with a surface that's dirty or oxidized won't give you a good ground connection.

A small disc capacitor, like a .01 uf goes from the center pin of the"keying" jack to ground. Any voltage rating 25 or above is fine. The .01uf value is not critical, either. About any value from .001 to 0.1 uf or in between will work about equally well. The panel socket usually comes with a ground lug that goes on the inside, under the socket's nut. A PN2222 or equivalent generic NPN transistor gets the emitter lead soldered to this ground, and its collector lead soldered to the center pin. A 10k 1/4W. resistor goes from the transistor's base lead to ground. The last part needed is 2 Watt resistor. If memory serves, a value of 100k is right. One end of this resistor goes to the base of the NPN transistor. The other end goes to one of the two lugs on the oscillator tube's tuneable coil. No, it won't reach. You'll need to splice a wire onto the 100k 2W part to reach the oscillator coil. What you want is called the "cold" lug on this coil. It has a fat 22k (I think) 2-Watt resistor on it, and a disc capcitor going to ground. The "hot" lug on this coil is the one you want to leave alone. That one has a bare wire directly to one pin on the adjacent tube socket. The end of the 100k resistor goes to the "cold" side, with the (factory) 22k resistor and disc cap to ground already on it.

Now, when the Spot is pushed, or the mike gets keyed, the NPN transistor will provide a ground connnection to the yellow wire.

A diagram would have been easier, but this will have to do for the moment. Anyone who can read the schematic of the transmitter should be able to make sense of this hookup, I hope.

Best of luck and 73

[cbrown]

Mar 18, 2022 20:15:21 GMT -5 masterplanner said:

Will this work on a bb30? Thanks

Quoted you to get the question you asked more visible.