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Thread: The TS-530/830 mod and upgrade thread

  1. #11
    "Island Bartender" KG4CGC's Avatar
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  2. #12
    Administrator N8YX's Avatar
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    Tip #6: Product Detector upgrades

    Also present on AG6K's "Circuit Improvements" page. Several modifications are made in this area. One involves swapping the OEM 1N60 diodes used in the product detector for low noise-figure Schottkys. The LO side of the bridge is unterminated; a resistor to ground fixes this. Next, a few components in the IF bypass RC network are changed - opening up the received bandwidth a bit, and as Rich noted "...you'll get the full effect of sky noise". The modification makes for a more robust sound from the speaker - and if less bandwidth is desired, the Narrow filters can be activated...or an accompanying SP-230 with its built-in audio filters can be used...or both.

    Component changes on the '530's IF Board are as follows. These are applicable to the TS-830 as well, though depending on production run, not all parts may need to be swapped. The '830's component designators are different and will be covered in another post.

    - R41 is changed from 6.8K to 2.7K
    - C35 is changed from .033uF to .01uF. This is a polystyrene unit
    - R42 is changed from 47K to 3.9-4.7K (I used 4.3K)
    - D16-D19 are changed from 1N60 to 1N6263 or similar Schottky parts. I got a bunch of these from K4EAA and matched them to .001v forward drop before installation

    Prod-Det-1.jpg

    A 100 ohm, 1/4w resistor is added from the junction of R39 and R40 to ground:

    Prod-Det-2.jpg

    (Insert obligatory Linda Hamilton "...terminated..." quote here.)

    Follow the service manual procedure and adjust the product detector via TC2. I used a scope and got the null down to the point that the LO energy was unobservable at the test point, the drain of Q4. I've tried using 1N5711s in my FT-90x projects and found the weak-signal performance to be a slight - but not a great - improvement. The 1N6263s seem to work better, at least in this application.

    FWIW, I checked sensitivity with a signal generator at 14 and 28MHz. I cannot turn it down to the point that the signal isn't detectable (.01uV or thereabouts), and the recovered spectrum is very low in noise.
    Last edited by N8YX; 06-14-2018 at 09:55 AM. Reason: Grammar
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  3. #13
    Administrator N8YX's Avatar
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    Tip #7: Balanced Modulator update

    Another one borrowed from AG6K. The modification cleans up the transmitted signal a bit at the balanced modulator. In the 530, diodes D27-D30 (1N60) are changed to the same type as used in the previous modification. Follow the service manual procedure and null the carrier after the IF Board is reinstalled in the radio. The mod is applicable to the '830 too, albeit with different component identifiers.

    I found it easier to do all IF Board mods at once, and in addition I replaced the large filter capacitors at the rear of the board with 450v, 105c-spec units while I had things apart.

    Bal-Mod-Diodes.jpg
    Last edited by N8YX; 06-14-2018 at 01:24 PM. Reason: Grammar
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

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