Question about Tubes for Yaesu FT-101E

Discussion in 'General Technical Questions and Answers' started by KB5FVD, Nov 19, 2009.

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  1. KB5FVD

    KB5FVD QRZ Member QRZ Page

    I inherited a Yaesu FT-101E, the Drake twins, and miscellaneous other equipment from my father, but bits & pieces are missing or not working in everything. I earned my Tech license in Oct & my General ticket in Nov and I'd really like to get on the air.

    The Yaesu seems to be my best bet for getting on the air fairly soon. I've ordered a mic from KK4WS, but I need the 6JS6C tubes for the final. The original tubes were NEC. I've been offered a pair of Fox Tango tubes for $50 for replacements.

    Will Fox Tango tubes work properly in the FT-101E? Is this one of those "too good to be true" deals?

    Thanks! Sandy
  2. WJ5O

    WJ5O Ham Member QRZ Page

    FT-101E sweep tubes

    Welcome to Amateur Radio Sandy,
    The best source of information about the FT-101E rig is the Fox-Tango group...

    I owned a FT-101E many years ago and often sorry that I didn't keep it.....
    I remember that sweep tubes made by different manufacturers required a slightly different procedure in neutralizing....

    The most experienced operators/technicians are available at:
    and the archives contain information about the different sweep tubes. :)
  3. KB5FVD

    KB5FVD QRZ Member QRZ Page

    Thanks, Bill! I'm now pending approval by a moderator to get into the Fox Tango group. Maybe I've missed it, but I wasn't able to find any info on Fox Tango tubes. Just speculating, it seems that that group should produce good tubes for the FT-101E.

    73, Sandy KB5FVD
  4. W5HTW

    W5HTW Ham Member QRZ Page

    Fifty bucks is a good price for a pair of finals for the FT101E. I replaced mine with a pair from Fair Radio, for 90 bucks, plus shipping!

    You might also want to replace the driver, the 12BY7A. It can be found easily and isn't nearly as expensive.

    Those sweep tubes require critical 'care and feeding.' You can destroy them in ten seconds. Literally. When you join the FT group, you will learn much about the tuning of that radio. With care, the tubes can last for years. But it takes true TLC and knowing at all times how to tune the rig and 'babying' those tubes during tune up.

    The rig was very popular with CBers because it could be easily modified to operate on 11 meters. Many of those rigs were CB'ized." That is, driven hard and put up wet. When it says 40 watts AM output, it means no more than 40 watts AM output!! Not 80, not 100. Just 40. And better to run a bit less.

    But the big problem comes in tuning. Inexperienced FT101E operators tend to tune slowly, double checking, and those tubes won't handle that!! I always advise anyone starting off with an FT101E to practice the tuning procedure with the power OFF. Run through it, as shown in the manual, several times, get the feel of the knobs, the sequence you will adjust them, and pretend you are seeing the meter readings you expect to see. Only after becoming familiar with tuning the rig power off, do you switch on the power and do it for real.

    I also recommend, once doing it for real, doing it with very low drive, just a few milliamps of plate current above the idling bias. Do it the old way - dip the plate, starting with the Load control as minimum. Then increase the drive slowly to get about 120 mils plate current, and redip. At that stage you can start to actually load the rig.

    Follow the procedure in the manual, but do it quickly! And I recommend monitoring plate current as often as you can during tune-up.

    They are good rigs.

    So are the Drakes. I hope you get the Drakes on the air, as they are absolutely one of the best ham rigs ever built, some claim second to Collins, but I actually prefer (and so do many others) the Drakes over Collins.

    Good luck, and welcome. Baby that FT101E and you will be a happy camper.

  5. NN0NN

    NN0NN Ham Member QRZ Page

    FT-101E Tubes and Mods

    Hi Sandy,

    You have inherited one of the finest transceivers made. I have been a ham for over 50 years and I own three of them.

    The 101's were designed to use the Japanese tubes. They drive differently than American made tubes. One time I replaced my driver tube with a GE tube (1970) and lost 40 watts of drive. I went back and exchanged the GE for a Raytheon and my power came back. I stayed with Rayethon for years and had very good luck. The US tubes were different in design than the Japanese tubes. A slight modification to C13 the driver coupling capacitor between the driver and finals is necessary to use US tubes.


    Open bottom cover.
    Remove all screws holding the internal chassis cover.
    Remove the two screws holding down the TC board (small adjustable caps)

    C13 is located under the top edge of that board near the chassis edge. This cap is brown in color is is a rectangle shape. This cap couples the driver to the output tubes. Its old and its changing in value. This changes the output.

    As stated before. If your tubes are American made, use a 10PF 1000v mica cap on the neutralizing cap. This cap is number C125 and has an original value of 100PF. There is a fixed value cap strapped across the variable neutralsiing cap that needs to be brought down in value radically if the rig is going to make stable power and neutralizing ok. Discharge the HV and get into the final cage. Check and see if the final tubes are Toshibas or another Japanese tube, or not. If so the existing 100pf value cap is correct. if they are USA made, the value needs to be brought down to 5~10pf @1000 silver mica dipped./1000 volts.

    While your there.. Replace C131. Its a 1000PF cap near the preselectors. This cap often fails and causing the Fuse to blow when you go on 160 meters. The plate structures are radially different between the japanese and US made tubes.


    Pull the receiver board PB-1181 which is located in the top front right corner, just under and too the left of the Plate tuning shaft. Locate the 3SK40M (Q1) FET that plugs into a socket on the center of the board. Carefully note it physical position and legs. Order a NTE454. Shop this FET around, the price can range from $9 to $20. When you have it in hand cut the long legs down to about 3/8" to 1/2" and bend them to replicate the 3SK40M legs. Unplug the 3SK40M and carefully plug in the NTE454. Be careful there is a hole that sits next to another but it doesn't have a contact in it. Look carefully where the 3SK40 legs are plugged in and which way the little tabs are pointing. Replace the board. This modification will improve the receiver reception.

    I am producing a double sided paper manual in a binder with the owners manual, service manual, schematic, and a section of all the known mods. I love my paper manual, it makes it so much easier to find what I want. It is sectioned off for each section of the radio with a special section on mods and notes.

    It takes me a long time to produce each manual since it is so large and I do each one on my printer. I think I am going to ask $39.95 for the manual and sell them by special order or on Ebay. If you are interested in the manual send me an email to:

    Good luck and have fun with your new rig.

    73's Len Morgan
    Cassville, Mo.

    Last edited: Nov 19, 2009
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