Outline of instructions to install the Nomad Radio Slider Converter in a Browning Mark III AM or Mark II transmitter.
** Packing List **
1) SC Ver. 1 board, with mounting brackets and mount screws attached
1) 5-inch piece of green-insulated #24 hookup wire, stripped.
1) 56pf NPO disc capacitor
1) 8pf Silver Mica capacitor
1) 4-foot (approx) low-capacitance shielded cable with prepped pigtails one end, molded RCA (phono) plug on the other end.
0) Tune up the transmitter on a GOOD crystal near channel 20 before taking anything loose. Note the carrier and the peak power with modulation. This will give you a way to compare the outcome when this thing is installed. Don't expect more power with the slider, but you should always have AT LEAST the same power after as you did before.
1) Find R2, a 22K 2 Watt resistor attached at one end to the cold end of L1. Remove the lead from L1. This will require a light touch. The terminals on the sides of L1 are pretty fragile and will not tolerate any amount of twisting or pulling. The lead on R2 is pretty thick and stiff. It will probably have been crimped in place before it was soldered, locking it in place. Melt the solder at this terminal, and see if the lead will "rock" slightly around the curve of the crimp. It won't come completely out this way. Use a pair of small-nosed diagonal cutters to clip the resistor lead close to where it comes out of the lug on L1. This will leave you plenty of lead length left on R2 to reach to where it attaches later. Melt the solder on the cold lug of L1 again, and see if the remnant of the resistor lead will fall out the opposite side of the lug now. Once it is safely out, the hole in this lug should have enough room in it to accept the two small leads that go there later.
2) There is a short bare lead from the other (hot) end of L1 to V1 pin 1. Clip this lead. There is a small disc capacitor C3 5 pf from V1 pin 1 to pin 2. Remove this disc and clear the hole in the pin 2 lug for the part that will go there next. Throw the 5pf disc (C3) away. The supplied 8pf silver mica cap should now be put in parallel with C1. C1 is a 10 PF disc cap strung across the two lugs of L1.
3) This transmitter contains a neon lamp wired as a "relaxation oscillator" that feeds an audio tone into the mike audio when the SPOT button is pushed. These parts are located on the tie strip just to the front of V1, between it and and the mike jack. Unless you are in love with this feature, remove R12 and R14, the neon lamp, the two disc capacitors C15 and C16, and the blue wire that runs from this oscillator to the Mike audio input just behind the mike jack.
4) This will leave you four empty lugs on this tie strip, all on the outboard end of the strip. Bend R2 around so the free end 1 will reach the nearest empty lug.
5) This tie strip is a little too long to suit this version of the converter board. Drill out the rivet holding the outboard ground lug of this strip. With diagonal cutters, clip the brown plastic between the (now-loose) ground and the empty lug inboard from it. This will leave you one empty lug on the end of the strip. The lug next to the outboard end already has the free end of R2 stuck in it.
6) The end of the SC board with the green and yellow twisted pair goes to the rear of the transmitter. The rear bracket will line up with the now-empty hole that held the rivet you just removed.
Hold the SC board in place with the rear bracket hole lined up with the old rivet hole, and mark a spot on the chassis through the front bracket hole.
Drill a 5/32" hole in the chassis deck there.
Line up the SC board brackets with the chassis holes to make sure they align well enough for the mounting screws.
7) Insert the free end of the 2200 uf axial capacitor from the SC board into the end lug of the tie strip. Insert the free end of the 100K 2W resistor into the next lug, the one with one end of R2 stuck in it. Now insert the two "keps" mount screws from the top of the chassis, the nut against the bracket hole underneath, at both ends of the SC board. The nuts are 5/16" wide, and will "catch" against the bracket when tightened. This prevents the nut from spinning. This tight fit makes it awkward to get the pilot end of the screw started on the nut. If you hold the nut flush against the bracket and just barely engage the pilot end of the screw into the bracket hole, it will be easier to start the the screw onto the nut.
8) Attach one end of the supplied 5-in. green wire to the tie strip lug with the negative end of the 2200 uf axial capacitor in it and solder. Route the other end of the green wire to pins 4 and 5 of V4 the 12AU7. These two pins are soldered to each other and to a pair of black wires.
9) Solder the end of the 100K resistor to the lug with R2 in it.
10) The green and yellow twisted pair of wires now go to L1. The green one to the "cold" side of L1, the one towards the center of the chassis. (Yeah, I know, this picture shows a disc added there, not a silver mica.)
11) The yellow wire goes to the lug of L1 next to V1, along with one lead of the supplied 56pf disc cap. The other end of the 56pf disc goes to V1 pin 2. Solder both ends.
12) The slider cable should be routed to enter above the chassis next to the power transformer, along that side to the front panel, then across the front panel to the grommet behind the channel switch. The yellow wire from the crystal switch to V1 pin 1 goes throught this grommet.
13) The center wire of the slider cable goes to the larger empty hole on the outer edge of the SC board next to the crystal trimmer cap. The skinny solid wire goes into a tiny hole just between the center of the 7310 chip and the board edge. Bending this wire over and soldering to the solder-side of the ground trace under the center pin of the 7310 chip will give this wire a little more flexibility than just soldering it to the board hole.
14) Plug the other end of the slider cable into your slider, and set it to the same channel as the receiver. Power up the transmitter and the receiver. If the SPOT button doesn't produce a carrier you can hear in the receiver, turn it all off and recheck your connections. If you hear the spot carrier, peak L1 and L2 for max S-meter on the receiver.
15) Assuming the transmitter passed the "SPOT" test, key the mike and peak L1, L2, Tune and Load on a channel midway between the highest channel and the lowest channel you plan to use. The peak on L1 will be very broad. L2 will have a sharper peak. Often it will be more effective to peak L2 for max modulated power, rather than using a dead carrier alone.