Yaesu FT-990 gets a Pan Adapter

Discussion in 'Radio Circuits, Repair & Performance' started by KD8UYQ, Jan 7, 2018.

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  1. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello All,

    In the late fall of 2017 I picked up this FT-990 at a local hamfest for a very good price. The seller said that it had low power out on all bands but occasionally would work fine. The transceiver was very clean, had the original box, the operator and service manual and a CAT cable so I decided to take it home.


    I was lucky because all I had to do to fix the low power output was take out the RF board clean the connectors with a bit of DeoxIT and re-seat the board. That was it. Full power output came back and the radio has been fine ever since.

    I took the accessories including the third part CAT cable, put it in the box, and stuck the box in the attic.

    Recently, I read a post here on QRZ about someone looking for a buffer board to interface their vintage transceiver to a PC using one of those inexpensive SDR USB sticks so that they could have a pan-adapter for their rig.


    FT-900 pan adapter.png

    I thought about it a bit and concluded that adding a pan-adapter to my FT-990 might be a fun little project to do during this very cold week and half that we all experienced. After spending a good bit of head scratching and web researching last week I finally got it to work but I thought that others might benefit from a "How Too" so that they won't have to stumble around as much as I did.

    Please let me know if you are interested.

    KC3BZJ likes this.
  2. KL7KN

    KL7KN Ham Member QRZ Page

    Ripley - Man, don't do that.

    If you post a teaser - post the piece! And - yes, I have a FT0990. Love it as it is the AC and DC version.

    Since I'm plagued with wide band noise, a pan display would be useful in tracking down & at least trying to elininate the nouse source(s).

    So, yes, post your How To
  3. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hi Don,

    Sorry sir, no tease intended. I like to ask first. Just because I think something is cool doesn’t mean that others do.

    I will start on the write up a little bit later on this evening.

    KJ4NOO likes this.
  4. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    I added a panadapter to my 990 years ago. I'd be curious to compare your apples to mine.
  5. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello again,

    Even though this "How Too" is focused specifically on the Yaesu FT-990 the instruction can generally be applied to other older radios that have CAT (Computer Aided Transceiver) capabilities.

    Here is what you need:


    A transceiver that has CAT capabilities and the firmware on board to support that function. For example my FT-990 has firmware revision 1.3. The older version 1.2 is suspect whether it will work with Omni Rig.

    An IF tap from your transceiver. Typically using some type of buffer board that you will have to install. The G4HUP Panoramic Adapter Tap (PAT) was a popular one from Dave Powis until he passed away. Fortunately Dave Calo has taken up to torch and sells PAT buffer boards for a wide variety of rigs. You can contact Dave via email at kd2c56@gmail.com for more information and pricing. I am using the PAT 50MS in the FT-990. It cost $34.00 with the connection kit plus shipping.

    A SDR receiver. I am using a RTL-SDR 2832U USB stick that I purchased from eBay about 4 years. I think it cost about $15.00. There a many others available with varying capabilities and associated costs

    A PC with a RS-232 port. My HP machine running Win 10 doesn't have any of the older style serial com ports like most of the PCs produced within the last 5 years or so. I added a Dual DB9 serial port card to my PC. This board cost about $16.00 and was purchased locally but you can get them on line as well. These older rigs know nothing about USB and I don't know if a USB to serial adapter cable will work. I do know that you will add more complexity to this project if your try to use one.

    A interface cable or converter box with cables to connect your radio to your PC. Without the CAT interface between the PC and your rig the information on the panoramic display is pretty useless. The interface cable that came with my transceiver is a LCU-3 made by Wigee Products but I think that company is no more. Ebay to the rescue again, just make sure that you are buying a computer interface cable and not a programming cable. They are not the same. At least that is true for the FT-990.


    I am using HDSDR for the Panoramic display and Omni Rig for control software between the PC and the radio. Both of these software applications are no cost downloads but survive on user donations.



    One more piece of software that you need is Zadig so you can place the correct "low level access" driver in the HDSDR folder for these inexpensive SDR receiver USB sticks to work for our application.



    Revue the shopping list and see if you want to proceed.

    I'll post the next steps tomorrow.

    Have a good evening.

    Last edited: Jan 8, 2018
  6. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello Max,

    I suspect that our implementations are very similar. What software did you use for your Pan-Adapter?

  7. KD8UYQ

    KD8UYQ Ham Member QRZ Page

    Hello all,

    The first thing that I need to do was to determine which IF tap buffer board would be required for the FT-990 and where to place it in my rig. For that information I referred to this internet article by Serge Stroobandt (ON4AA) which he describes in detail where to tap into the 1st IF stage of the FT-990.


    Armed with that information I ordered a PAT 50M5 buffer board from Dave Galo (KD2C). The instructions that come with the PAT board are very good but read the disclaimer. If you are not comfortable taking the cover off your perfectly good radio, pulling the IF board, and adding this board then find someone that you trust to help you with this part.

    In my case I soldered two wires from the buffer board to two pins on the J2002 connector on the IF board. IF IN on the buffer board goes to pin 2 on the J2002 connector (RX IF IN). The +VDC pad on the buffer board is connected to the FT-990 IF board via pin 6 on J2002. This pin is labeled R12 on the schematic. R12 is a +12 volt line that is active when the radio is in receive mode and deactivated when the transceiver is transmitting. I followed the recommendation from the instructions that states "the power connection must be made at a point where there 8 - 13.8 VDC is present on receive and off during transmit mode." The ground for the buffer board is via the shield of the RG-178 cable going to the SMA connector that was added to the back of my radio.

    The FT-990 IF board before the addition of the PAT buffer board.
    FT-990 IF board.jpg

    Same IF board with the PAT board mounted and connected to J2002
    FT-990 IF board with buffer BD.jpg

    Another look at the IF board with the PAT daughter board now added and the routing of the RG-178 cable to the SMA connector.
    Buffer board on FT-990 IF board.jpg

    If you didn't know better you would think that the radio was built this way.

    Here is the rear panel of my rig with the SMA connector mounted above the External ALC RCA jack.
    FT-990 IF tap output connector.jpg

    At this point I tested the transceiver and once satisfied that everything was as before the top cover was put back in place.

  8. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    It appears you tapped the IF after the roofing filter. This severely decreases the bandwidth you will see in HDSDR. That was my hunch when I looked at your screen shot. If you want to see more of the band, move your tap to the RF UNIT, at the junction of T1005 and T1010. This is before the roofing filter. It will look like this...


    It's a matter of personal opinion. I tried both, but I prefer to see a much bigger slice of the band.

    Nice article,
  9. US7IGN

    US7IGN Ham Member QRZ Page

  10. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    Considering the amount of time I actually have the panadapter running, I'm glad I didn't spend a lot of money on it. It's nice to have it when I need it, but the display on the PRO3 is adequate for most of my operating.

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