Modulating the FT-1000MP Balanced Modulator Directly from your External Mike Audio Processor or Audio Equalizer. As practically all other SSB transceivers use a IC balanced modulator, this modification may be adapted to most all makes and models . Also see my Mike, Processor page.
Note: follows; a compromised, simple mod, where no original parts need be changed or boards be removed. Note: To fully transmit your new audio Highs' (up to 6 KHz audio freq) first change out the original 6 KHz filter to a 12 KHz below !
The new input created below is designed to be driven by the Behringer processors and or equalizers ( Note; I only use the Behringer Processor ) (the new digital or old analog models) which state their maximum output levels to be +21 Db at 60 ohms unbalanced. On AM the master output fader is about zero (straight up) and on SSB about +3. Although VOX won't operate (only manual PTT) when using this new input your normal mike input with VOX and all other modes are normal. I use a foot switch with a .1 MFD disc ceramic shunt RF bypass cap at the PTT plug.
Insert low level audio through one one 110 Mfd non-polar cap (make this cap with two 220 Mfd. @ 25 volt Electrolytics in series, connecting their negatives together to make one 110 Mfd non-polar cap) in series with a 270 Ohm 1/8 th watt Resistor into pin 5 of Q3046 ( uPC1037H ) (the 7 pin inline IC), which is the transmit balanced mixer (mount the 270 ohm resistor at the IC). Very gently bend the IC slightly towards the left side which exposes the PC board IC solder pads. Pin 5 (on the schematic) of the 7 pin IC is 3 pins in from the rear apron ( and DDS shielded box ). Next, using a small hot iron I quickly tined the Pad then the short end (3/8 th inch) of the 270 ohm resistor and tacked it onto the IC audio input pad securely. The other end of the resistor is joined to the plus side of cap and the minus side of cap goes through shielded line to new RCA connector on rear apron, with its 270 ohm shunt resistor.
To locate Q3046, the balanced modulator inline IC remove the bottom cover and measure 4 inches inward from the external patch jack on rear. From the left side (headphone jack on front, AC line cord on rear) measure in 3 1/4 inches.
I mounted a female chassis mount RCA jack in a hole drilled (watch the metal filings, magnetize the drill bit) on the rear panel very close to the "G" in GND.
Making sure no metal fillings remain inside the transceiver is more than critical! And used 1/8 inch Teflon shielded cable, grounded at RCA connector and DDS shield near balanced modulator, to bring new audio input to rear. At this connector I mount a 270 ohm shunt resistor to ground. Below is an early schematic which does illustrate the uPC1037H balanced modulator. I am currently ( 15 JAN 04 ) using only the Marshall MX990 Mike and Behringer VX2496 Processor with its mid band parametric cut and presence 3 KHz and Breath 10 KHz rise adjustments.
Continuing along but Requiring Filter board removal follows;
A necessary component change to properly transmit or receive sibilance above 3 KHz without attenuation in AM , requires a change of the Existing internal 455 KHz 6.0 KHz filter used in many modes, selectable at the front panel (labeled "6.0K") which is CF2002, a Murata CFW455HT, 6 pole ceramic filter, which is 6 KHz at Six Db down, widening to 18 KHz only 40 Db down. This physically is a small black 11 X 7 mm rectangular filter hardwired on the left side of the main filter board. The CFW455F ordered is 12 KHz @ 6 Db and 25 KHz@ 40 Db down allowing one to receive or transmit up to 6 KHz of sibilance. When population is high I can limit my transmitted sibilance with my DSP-9024 to a much lower total bandwidth with its DSP steep skirted side of -45 Db. down. For receive bandwidths on AM for Wide I use this new 12 KHz filter, medium I use a INRAD 10 KHz 455 KHz Collins Mechanical Filter, narrow a INRAD 6 KHz high IF crystal filter. For filter positioning see my FT-1000 index page. Spec Sheet; muRata Ceramic Filters Collins 10 KHz Mechanical Filter
Expect to knock the two s-meter pots off proper setting. First you might want to mark their original setting. Removing the old CF2002 6 KHz filter requires a good solder sucker, hot iron and patience. I had the best results holding the iron on the board top with the sucker underneath. I emptied all the holes except one in the middle. Once you remove the old filter try heating some solid 22 gauge wire and running it through any remaining PC board holes to open them up. Next I pushed the new filter in while heating the obstinate hole from the bottom. What a pleasant experience transmitting and receiving through the new filter. Hmmm, now where did my muRata 8 KHz for a 455KHz receive position go? Bill, AF1S recently helped me correct this page. Also see my FT-1000 page for more filter info.
I just ordered a new 12 KHz muRata CFW455F filter to replace CF2002 from Ohio for $4.77 here on filters at Electronic Surplus Inc
A New Inexpensive Studio Condenser Microphone and audio processing; digital Behringer & Marshall