Here's the first attempt at a "How2" install a gadget we call the "Peel'N Stick Variable Key".
It's configured for easy installation. Like most of our odd widgets it came about to save labor here performing a popular mod.
It's designed to fit neatly in the Cobra29 type radios, but works in most any AM-only CB. It has two bare wires coming out the bottom. They go into the two holes left by removing the jumper wire that feeds the radio's driver transistor. It's usually marked "JP36".
A ground wire coming out of the top edge of the board goes into a hole in the radio's circuit board at the rear corner.
You may have to scrape mask paint to expose the ground foil, or simply strip enough from the ground wire to reach and lap-solder to a solder point on the board.
The three wires that go to the front-panel control are marked "CW" for clockwise, "Wiper" for the center lug and "CCW" for the minimum end of the control. It's probably easiest to simply unhook the wires from the radio's SWR Cal control and use it as your carrier control. The PNSVK is built to match the 5k pot used for the SWR Cal. Other value pots will work. I'll probably just pack a 5k control that fits the front panel of the 29 radios with the board. You can mount it where you want, or replace the factory control if someone has already roached the pot's resistance element with a bogus hookup in the past.
The heat sink surface should be prepared first, by swabbing it with rubbing alcohol or your favorite non-residue solvent. This insures a good bond with the double-sided foam's adhesive.
The double-sided foam tape we use is a commercial product made by 3M called "VHB". The guy we got it from said it was used to attach serial number plates to diesel engines. We have found that heat strengthens the bond. The drug-store double-stick foam tape tends to harden and come loose when exposed to heat. This stuff doesn't.
Once the bare wires are inserted into the holes where JP36 was removed, line it up first before pressing it against the heat sink. Once it has adhered, it won't want to come loose. I recommend a good squeeze with needle-nose pliers just to be sure of a good bond.
Lordy, it's past my bed time. I'm gonna post this and just come back later to proofread and see that I didn't scramble the order of the images.
This kit isn't ready for prime time just yet. The first samples are going out to folks who will be the "guinea pigs" to see if we screwed anything up with this first production batch.
Oh, that trimpot on the board serves to set the minium carrier power. Just seeemed worth the extra bit of trouble to have that.
More later.
73
It's configured for easy installation. Like most of our odd widgets it came about to save labor here performing a popular mod.
It's designed to fit neatly in the Cobra29 type radios, but works in most any AM-only CB. It has two bare wires coming out the bottom. They go into the two holes left by removing the jumper wire that feeds the radio's driver transistor. It's usually marked "JP36".
A ground wire coming out of the top edge of the board goes into a hole in the radio's circuit board at the rear corner.
You may have to scrape mask paint to expose the ground foil, or simply strip enough from the ground wire to reach and lap-solder to a solder point on the board.
The three wires that go to the front-panel control are marked "CW" for clockwise, "Wiper" for the center lug and "CCW" for the minimum end of the control. It's probably easiest to simply unhook the wires from the radio's SWR Cal control and use it as your carrier control. The PNSVK is built to match the 5k pot used for the SWR Cal. Other value pots will work. I'll probably just pack a 5k control that fits the front panel of the 29 radios with the board. You can mount it where you want, or replace the factory control if someone has already roached the pot's resistance element with a bogus hookup in the past.
The heat sink surface should be prepared first, by swabbing it with rubbing alcohol or your favorite non-residue solvent. This insures a good bond with the double-sided foam's adhesive.
The double-sided foam tape we use is a commercial product made by 3M called "VHB". The guy we got it from said it was used to attach serial number plates to diesel engines. We have found that heat strengthens the bond. The drug-store double-stick foam tape tends to harden and come loose when exposed to heat. This stuff doesn't.
Once the bare wires are inserted into the holes where JP36 was removed, line it up first before pressing it against the heat sink. Once it has adhered, it won't want to come loose. I recommend a good squeeze with needle-nose pliers just to be sure of a good bond.
Lordy, it's past my bed time. I'm gonna post this and just come back later to proofread and see that I didn't scramble the order of the images.
This kit isn't ready for prime time just yet. The first samples are going out to folks who will be the "guinea pigs" to see if we screwed anything up with this first production batch.
Oh, that trimpot on the board serves to set the minium carrier power. Just seeemed worth the extra bit of trouble to have that.
More later.
73
