FDK Multi 2700 Multimode VHF transceiver with Oscar

FDK 2700 multi

Service manual and schematic diagram

An interesting radio from era of being on the cusp between analogue and digital electronics capitalising on space communication by incorporating a 10m Oscar down link receiver.

image of FDK Multimode VHF Transeiver with 10m Oscar receiver

FDK Multimode VHF Transeiver with 10m Oscar receiver

Image borrowed from RadioPics database until I’ve taken one of my own

Files, those elusive and exciting documents you’ve been hunting for for the FDK Multi 2700

FDK 2700 Multi owners club?

who’s got one? Well I have and so has:

  1. David G7SBK
  2. Rick WK4R

Drop me a line if you’d like to be added the list cause you have one too.

How many FDK 2700 Multi’s were made?

I don’t know. However, during World War II a similar problem was poised with the Wehrmacht Tiger Tank. As a formidable fighting weapon Britain was concerned about how many of these fighting vehicles they might be up against. Some mathematicians were tasked to work this out, and history has now labeled this The German Tank problem.

“Alex”, you say, “what has this got to do with Amateur Radio?”

Well the same problem came up with the Drake 2B recently. A group of enthusiasts were wondering how many Drake 2b transceivers were made. Using the same process and analysis of the serial numbers the likely number was arrived at.

So if we can collect the serial numbers of those radio’s still in existence we can make a good effort to work the answer out. But I’d need to hear from you with your serial number.

Updates etc for this rig available on this site see [opens in a new tab]


26 comments to “FDK Multi 2700 Multimode VHF transceiver with Oscar”
  1. Thanks for posting the material on the 2700. My unit is s/n 87229.
    Still using it, despite it being a beast and lacking modern features- does just fine on packet, and the VFO makes for a handy signal source at low power. Some rigs are just too useful to retire, like some people.

  2. I have the FDK Multi 2700, it came from Germany. Only transmit from 144-146mhz, would like to get it to transmit from 144-149mhz, any help would be a great help…


  3. Given a FDK-2700 today as a restoration project which if I can get it back in working order will probably be offered to my local radio club. Rob H G0HRT

  4. I have one. Inside it says “Passed Inspection 1976.” Sn 92171. Just had the OX-117 board go out. Anyone got a spare so I can get this great radio back up?

  5. As I have said I have a FDR Receiver
    I notice that one of the caps on the rear of the unit is missing
    It is a 10 pin cap
    I think this may be the reson the radio is not working
    Would any one know where I might obtain one of these caps
    Any help would be appreciated

  6. I have just been given FDK Multimode-2700,, minus the mic, and the four pin power lead that may be a squire four pin Jones plug ,,can any one help me that knows were I can get one of these power lead plugs ,,Thank you for your time
    Colin GW0IRP

    • What did you do for a microphone? I also bought one without a mix and am having a hard time finding on that will work. Ideas or leads to find one?

  7. “www.concept9.co.ukFDK Multi 2700 Multimode VHF transceiver with Oscar | www.
    concept9.co.uk” genuinely causes myself think a small amount more.
    I actually appreciated every particular portion of this blog post.
    Thanks for your time -Barb

  8. Ran across your site – just what I needed in the way of manuals; many thanks. I have owned one of these rigs since 1987 and it is QC labeled Mar 29, 1977 on the PA shield. No serial number that I can find, however.

    Having two problems with the rig – perhaps someone can help or wants it for a parts/restoration project:

    1) PA breaks into oscillation when its trimmers are aligned per the service manual and this has been confirmed on a spectrum analyzer. It’s especially noticeable when transmitting SSB and the oscillation is very near 145MHz.

    2) The -600KHz offset crystal (16.300MHz) appears to be bad. No output. The socket/trimmer circuit checks out.

  9. Daniel: to transmit outside the 144-146 area, look in the schematic all the way to the right, the K4-2 relay controls current from either the S4-5 (Synth 1 MHz knob) or S7-9 (VFO MHz knob), what pins on the knobs are connected determines where it can transmit. In the schematic the positions for 144 and 145 are connected, enabling transmit on those bands.

    The VFO knob is easy to get to, for the Synth I soldered a wire jumper across the input and output since I could get to it without disassembling the whole front panel.

  10. I own KLM Multi-2700 serial number 11475 so it must be a real late model. This the second one I’ve owned. Bought the first brand new in 1977 or so and sold it a few years later. The current one was purchased off eBay in 2005 for $100 complete with factory microphone. Still an impressive performer and sounds great on all modes.

  11. Serial number 14380, QC stamp from late 1978 inside.

    I modified mine to work 25/12.5 kHz channels, and put a small opamp on the FM discriminator output to bring the FM volume up afterwards. I also had problems with the output drive losing power, turned out to be a bad solder joint somewhere in the output booster, probably one of the ground plane links.

    I’m also looking into upgrading the LO to use a TCXO since it drifts a fair bit with the seasons (I keep it near a window).

  12. hi and thanks for the wonderful blog! I have been seeking for stuff like to this.
    i’ll be checking your rss so i won’t miss out the good things!
    again, magnificent web page remember to keep
    it up! Please pardon me if my english is not good.

  13. Your mode of describing all in this article is actually fastidious, every
    one can effortlessly be aware of it, Thanks a lot.

  14. I´m owner of a multi 2700 too. It´s a very good transceiver. My father bought it, I think, 1977 or 1978. He was a radio amateur, too. The Serial-Number of mine is 11418.

    Best regards, Jutta (DO4PY)

  15. I have a Bigear Type-1 which I believe is related to the Multi-2700. It looks like the Multi-3000 but does not have the 2 switches below the VXO.
    Does anyone have manuals for this radio?
    Thanks, dennis in Missouri

  16. Just got a 2700 on Ebay, real cheap. And it has a problem. A real screwy problem. I am shelving it for now for another day, too many things I should be doing instead… And thanks for posting the manuals. I made those images into a pdf. Anybody wants a copy I’ll put it on the web site.

    Maybe someone has run into this. VCO instability. Not mechanical. Transmit FM, you hear noise in the background. On SSB it seems like phase noise and I found one spot on x-3 to bypass and it improved that a whole lot. But most noticeable in SSB, when modulating the VCO frequency “wiggles” in response to modulation. So…added bypassing at the VCO, PLL, loop filter, etc. Did an alignment on the X5 and X6, where I did find an issue. BTW, I know it is the VCO since it is the only thing at 127 mhz coming from the radio, and listening to its hetrodyne on the IFR. All other xtal osc are rock stable, so to speak.

    Now in the X5 and 6 alignment, at one point it says to ground test point 1 (11 mhz *2 buffer) which removes a mix component and should unlock the loop and cause the VCO to wander to some place where it feels comfortable. This is where I start seeing something very odd. The frequency stays around where it was and it shifts very fast up and down about 10 khz. But not the 137 mhz the manual hints at. Not even close. It says to “adjust” the VCO coil to make this happen, but moving a turn on the coil did absolutely nothing. Turn radio off then back on with clip lead still in place, VCO doesn’t start at all. Looked on a spectrum analyzer, it ain’t there. Unclip the short and after power off/on it comes back. Tried shorting the loop voltage which also stopped the osc, off/on to restart.

    I have to get some shut eye and stare at the schematic again to see what this all means. Oh yeah, the procedure to monitor test point 2 and adjust T2-T5 for max, looking for 1.5 volts…well, got 0.1 volt there.

    So I put it back together. Maybe part it out??

    I have 4 other 2 meter SSB rigs already. I didn’t really need this but the price was good. Technically I consider myself pretty good. This one is a head scratcher, but most of the problem is back and forth top to bottom and no easy way to work on the VCO modules in circuit…

    Allstarlink node 2360

    • Hi George,
      Sounds likes you’ve got your hands full with this little problem. You sound like a man that’ll get it solved with your greatest asset – persistence 🙂

      The only thing I might offer is to seperate out the VCO from the rest of the circuit and see if the fault remains within that unit or if it works correctly on its own. I’ve had oscilators that fail to operate when long unexpected leads are attached so I am not entirely surprised yours is doing this under similar conditions.

      A can of freezer spray may help to blanked locate the area that’s causing trouble – its probably the usual leaky cap or duff solder joint that’s causing the issue. It sounds like its worth investigating Test Point 2 up-stream from here as your voltage is well down at .1 volt. But you know that already 🙂 Try to seperate out your input and output from each stage if you have to and give them a dummy load to work into, then assess if the stage is doing what you’d expect it to. The stage ahead can’t work correctly if the output of the previous stage is out of whack. That locates your problem into a stage, then its a case of looking into that stage more closely.

      Good luck and keep persistence on your side 🙂


  17. Hi please add me to the multi-2700 owners list i have one and i absolutley love it it’s all i have for vhf would not be with out mine needs an alignment as power is only 3 watts and i have to shout to get that on ssb 🙁 but atleast it still works :p
    cheers paul “2e0pbp”

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