1. Problem. The main receiver may receive signals from either the main antenna jack, or the RX ANT jack. A switch can be used to make this choice. Also, the subreceiver may receive signals from either the main receiver front-end (and whichever signal source the main receiver has chosen) or from the SUB RX ANT jack at the back of the BPF unit. A switch can be used to make this choice.
The problem is that there is only one switch on the front panel for these two independent choices. A little switch, S1001, on the RF board selects which function the front panel switch will control. The function for the other antenna choice is then completely lost.
Most operators choose the setting which allows the front panel switch to control the main receiver antenna. Then the subreceiver is permanently connected to the main receiver front-end; this leaves the BPF out of the circuit, and limits the frequency range of the subreceiver, as in the MP. In this common situation, the BPF has no function, and the subreceiver is unable to use a separate antenna.
2. Solution. Add another switch. This switch will work exactly as if it were the front panel RX ANT switch, and as if S1001 were set for the subreceiver.
The modification is electrically extremely simple and quite obvious; the only effort is in mounting the switch and connecting the wires. The new switch is added on the back of the BPF unit, between the attenuator switch and the subreceiver antenna jack. The modification requires no circuit board mods, no surface-mount work, and only a few parts.
Is it a good idea to drill holes in the radio? I never worry about resale value, and would never sell this fine radio.
Anyway, a knowledgeable buyer would appreciate the modification. The switch is quite inconspicuous. In any event, the holes are not in the radio proper, only in the hidden BPF chassis, and in the little black replaceable cover.
3. Operation.
- The front panel switch controls only the main receiver.
- The rear switch controls the subreceiver. No labels are needed on the switch. DOWN towards the antenna jack selects that jack, and what is usually the lower antenna, such as a Beverage. UP selects the main receiver antenna source, and what is usually the upper antenna, up on a tower.
- In most cases, the RX ANT and SUB RX ANT jacks can be tied together with adapters and short jumpers, and then connected to one auxiliary antenna. This will allow the auxiliary antenna to be used with either receiver, or both at once.
4. Materials.
- One miniature switch, SPST, 1/4 inch bushing. Single pole; double pole would be too wide. A sub-miniature switch, 3/16 inch bushing, might be even better.
- Two pieces hook-up wire; 24 inches and 2 inches. Not too heavy or thick. #24 stranded, 0.010 inch insulation. Alpha #1854 is okay. Best is Alpha #7054, irradiated, solderingiron resistant, Mouser #602-7054-100-01, www.mouser.com.
- Two small cable ties.
- Five small glass jars to hold the different types of screws.
5. Installation. This procedure is not specified in great detail here, but hams with experience working on the FT-1000D (this does not include me) will find the modification very easy. Radios from different production runs may have differences in layout; they might not correspond to the steps below, and require slight changes in the procedure.
5A. RF board.
- Remove covers from radio.
- RF board is to be lifted sideways.
- Remove three coax cables near outer rear corner; sketch positions, cut off cable tie.
- Cut off cable tie from large wire bundle at outer front.
- Remove cardboard shield.
- Switch S1001 to R ANT.
- Remove three screws from rear, which hold connectors. Note that one screw is machine, two are taping; these should not be interchanged.
- Remove board screws and lift board sideways.
- Strip and tin one end of long wire only 1 mm; tack onto outer terminal of S1001; this is the E BPF terminal.
- Run wire up to board top through the unused corner hole.
- Replace board; shield, 6 board screws, 3 rear screws.
- Replace cables.
- Replace two cable ties.
- Feed wire up along corner, and over above BPF.
5B. BPF.
- Remove BPF unit.
- Remove black mounting plate.
- Remove shield.
- Remove BPF board from BPF chassis. Lead unsolders from coax connector, which stays on chassis.
- Drill hole for switch in BPF chassis lip between attenuator switch and coax connector.
- Removing the BPF circuit board ensures that all drilling fragments can be removed from the chassis - one fragment can kill a radio.
- Drill matching hole in black cover plate.
- Attach switch to chassis; body close to lip, no spacer nut inside chassis. Orient switch according to convention noted above.
- Install BPF board. Attach black plate.
- Connect one side of the switch to +13. There is a convenient fairly large +13 pad on the relay sub-board; it is easy to locate because there are only four leads to the sub-board: two antenna leads, a ground lead, and the +13 lead. Early versions of the BPF might not have a subboard.
5C. Final installation.
- The wire is fairly long for two reasons. One is installation convenience. The other is to allow slack in case the RF board is to be lifted in the same manner at a later date.
- Position the BPF unit on the workbench behind the BPF opening.
- Run wire up in corner, over and above BPF area, out through opening, and into the BPF chassis through the cutout for the two connectors.
- Attach wire to switch. ON should be with the switch toggle towards the coax connector.
- Attach BPF shield.
- Install BPF unit.
- Look for left-over hardware and things that I forgot to mention.
6. Note. The setting of switch S1001 on the RF board should not be changed to E BPF after this modification is installed. There is no reason to do so. However, if the switch is set to E BPF, and the new subreceiver antenna switch is set for the subreceiver antenna jack, and the front panel RX ANT button is pressed, then Q1026 will receive 13 volts from two different sources, connecting these sources together. These are probably ultimately the same source (I didn't bother to check), so it would be okay, but it's not a good idea. (The schematic on page 29 of the operating manual is only a simplified version, and is totally misleading.) Removing S1001 would eliminate any hazard (and eliminate the most unfortunate component in the radio). A drop of epoxy cement, or red nail polish, on the switch to freeze it would be the easiest solution.
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