Kenwood T-599A VFO - No RF out??

Discussion in '"Boat Anchor" & Classic Equipment' started by AA7FY, Sep 27, 2020.

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  1. AA7FY

    AA7FY Ham Member QRZ Page

    UPDATE - in my search for a Q1; 3SK22 I found a VFO from an 820s and after comparing the schematics I grabbed it; plus price was right to experiment with. Looked physically identical (part wise, layout wrong), and the alignment in each of the service manuals ( T599 and the TS820) were extremally similar.

    I tested the 820 VFO with my bench power supplies and it checked out great. Now I had a working unit to play with.

    Running through married of a clip lead maze of runs using the 820S VFO and the T599 in every combination I confirmed that my T599 board was in fact the issue; not the coil repair, and at this part of the journey I was tired of working it and the 820 VFO was by far cheaper than a NOS 3SK22 and now a simple solution. With the new board installed, the T599 VFO adjusted spot on and the rest of the alignment went well. Should have it on the air by weekend!! I believe Q1 was the part that took the hit based on the comments and my tests. I have stripped the old board and the only part that I could not confirm with testing with my lab equipment conclusively was Q1; again my final solution was the most cost effective. Thanks for all your help!
    CX3CP likes this.
  2. AA7FY

    AA7FY Ham Member QRZ Page

    On the air and back to the bench!! Put the twins on the air today and checked into the noon time net - great report and spot on frequency report using both R599 and T599 VFO’s!! Reason I’m back on the bench is the dial read outs were off. R599 low by 125Khz and T599 low by 25Khz. I’m thinking it’s a mechanical alignment from when I had them apart for physical cleaning. But they run great!!
    CX3CP likes this.
  3. W9GB

    W9GB Ham Member QRZ Page

    STATIC and ESD can Destroy Dual Gate MOSFET “3SK” devices
    (newer models have ESD protection)
    Earl Andrew’s, VE3AB tested a variety of replacement FETs for the Toshiba 3SK22 ...
    he sells 3SK dual gate MOSFET.

    3SK series Dual Gate MOSFET (NOT All have ESD protection)
    He has a Variety of Types and Tests ALL before shipping.
    3SK177 GaAsFET dual gate 10 in stock 4 pin mini mold surf mount UHF gain up to 20db nf 1.1db
    3SK19GR qty 2 or 3 removed from a Kenwood TS430s board- x48-1370-00 IF UNIT BOARD has some p
    3SK22GR very short leads 3SK22GR
    3SK40 xref to NTE222 $5.00 3SK40 N ch dual gate mosfet TO72 small metal can pack p
    3SK41 xref to NTE222 QTY 6 some are pulls all will be tested good price for tested pulls $3
    3SK45 xref to NTE454 $5.50 3SK45 6 that are n.o.s and (2 PULLS) Nch dual gate mosfet TV,
    3SK48 no nte nr – this is in the IC22 (pull from IC22) RF amp dual gate mosfet 3SK48
    3SK59GR (K59GR) xref to NTE222 dual gate mosfet N channel stored in bin WOL222 (the red met
    3SK73GR removed from IF Unit junked TS430S board (other 3SK73GRs as well) stored in TS430S pu
    3SK74 stored in red drawers general fets bin but being moved to green fet tray10 also q23 and
    3SK97 no nte nr.- full datasheet hard to find $17.00 3SK97 Older part
    Cross Reference: NTE 222
    NTE Parts Direct ($14.12 USD):
    Available from Amazon (NTE Electronics supplier), for more $

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