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Re: [FT897] Re: Is the radio really worth it?

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  • Bruce Nanney
    Hey Rob, I m still having trouble defining where my test points are for the idle bias current tuning. My diagrams are not clear. Do you have something more
    Message 1 of 38 , Nov 30, 2005
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      Hey Rob, I'm still having trouble defining where my test points are for the idle bias current tuning. My diagrams are not clear. Do you have something more defined? I'm not willing to tune till I know for sure where everything is. Thanks, Bruce KD4BOH.
      ----- Original Message -----
      From: wb1aex@...
      To: FT897@yahoogroups.com
      Sent: Thursday, November 24, 2005 5:08 PM
      Subject: Re: [FT897] Re: Is the radio really worth it?


      Hi Bruce,

      The service manual calls the exciter adjustment points VR1001 and VR1002 but as I recall, on my 897D they truncate the names on the circuit board and label them as VR01 and VR02. Just orient the component diagram the same way as your board and check the position of the test points and pots on the board and you will not go wrong, they are exactly where they appear in the service manual pictures. They do the same kind of thing with the HF/6 and VHF/UHF PA adjustment points. Incidentally, for the exciter adjustment, it is NOT necessary to switch S1001 off then back on. All it does is open the test points for the pre-driver and driver stages, which is not necessary for adjusting the exciter and PA stages.

      When you get all metered up, please record your factory settings, I would be very interested in what you find. For the exciter drivers, record the total current, then turn VR1001 fully counterclockwise to shut down one driver so you can determine how much current each driver was pulling by subtracting the resulting current from the total. Mine were horribly unbalanced (10ma and 70ma). As a safety precaution, when you are doing these adjustments, you should make sure you are connected to a dummy load, AND make sure your SSB mic gain is set to 0. I inadvertently blew the fuse in my Fluke Multimeter when I dropped a screwdriver on the workbench while keying the transmitter to check my final adjustment of the PA. It obviously was NOT designed to handle 22 amps!

      Rob, WB1AEX
      ----- Original Message -----
      From: Bruce Nanney
      To: FT897@yahoogroups.com
      Sent: Tuesday, November 22, 2005 11:43 PM
      Subject: Re: [FT897] Re: Is the radio really worth it?


      I downloaded the ft897 manual, but the VR and TP numbers don't match on the board. Is the 897D version different?
      Bruce KD4BOH.
      ----- Original Message -----

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    • wb1aex@hotmail.com
      Hi Bruce, Glad your rig is working as it should! I did not mess with the pre-driver or driver settings on any of the rigs I have checked, due to the small size
      Message 38 of 38 , Dec 6, 2005
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        Hi Bruce,

        Glad your rig is working as it should! I did not mess with the pre-driver or driver settings on any of the rigs I have checked, due to the small size of the test point pads. I believe you would have to solder leads to the test points to connect to, and it looked pretty tight in there. To be honest, after doing the exciter and final stages, all three of the rigs I checked sounded extremely clean, so I was not motivated to investigate further. Thanks for reporting your findings, it looks like things were way out of spec on yours as well. It must have sounded very gritty/dirty/distorted in sideband mode!

        Look forward to working you on the bands,

        73,

        Rob WB1AEX
        ----- Original Message -----
        From: Bruce Nanney
        To: FT897@yahoogroups.com
        Sent: Monday, December 05, 2005 10:02 PM
        Subject: Re: [FT897] Re: Is the radio really worth it?


        Hey Rob, I did part of it. Sounds and performs well.

        Exciter was measured at 86ma ,HF PA was at 83ma, and VHF/UHF PA was at 76ma. So I retuned them as DG2IAQ wrote about.

        I did not find the pre-driver or driver test points yet.

        Thanks for the help. Bruce KD4BOH.
        ----- Original Message -----

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