Yaesu FT-101 HF Transceiver Web Page

Presented by Fox Tango International.

Yaesu Musen Co. FT-101

(Yaesu Wireless Co.)


 FT-101 Final Amplifier Circuitry

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Original components in the FT-101 Tank Circuit Green Banded Toshiba Finals.









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With  advancements in solid state technology and television sets changing over to transistorized horizontal sweep circuitry, sweep tubes were becoming in short supply by the middle of the 1970's.  The original FT-101 transceiver as originally equipped from the factory came with Green Banded TOSHIBA finals and there were perfectly matched for the job intended.  At the time they were inexpensive and plentiful and used in just about every television set in the country.  With the changes in technology Toshiba finals started to disappear by the mid 1970's. Yaesu then changed to NEC brand final amplifier tubes in their later production of the FT-101E and FT-101F transceivers. 


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    Look into        PA Tank Coil           12BY7              CIRCUIT


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In a search for a suitable replacement sweep tube Milton Lowens of the Fox Tango club reached out to Korea for   replacement tubes which he offered to the club with the Fox Tango Brand name and Logo.




Proper Transmitter tune up.

Yaesu technical bulletin on the proper transmitter tune up. (This is all fine and dandy nice to know info.)  Let me however make one very big suggestion to you the reader  regarding item step "E" in this note.   Always, always!  Leave the transceiver meter switch in the (I.C.) power amplifier current position allowing you to monitor  your current on the P.A. tubes. This is the only indication you have should something be going wrong in this stage of the transceiver.  The 6JS6 tubes, while still available from many sources are getting to be very expensive.   Back in the days when this bulletin was written by the Yaesu staff, tubes were $8 a piece.  Now they are nearly 10 times that amount from some sellers.   So we recommend to you in regards to step "E" that you always, now and for ever more as long as you attempt to run an FT-101 of any model, that you should  watch the I.C. final current during the entire tune up procedure,  while using an external meter to watch for your power output.  This will basically tell you everything you need to know as to what is going on inside the PA / power amplifier stage. Idle current should roughly be 50 to 60ma, keyed down on SSB mode with no modulation applied. You can tell other thing about what is going on in the PA by watching your current meter, should the I.C  meter start  jumping around erratically during tune up, it is safe to assume your PA is oscillating and in need of neutralization.  If the current starts to creep up during key down periods, you may have the classic symptom of a leaky coupling capacitor from pin #7 the plate of the driver tube, and the list goes on.  So watch I.C. all the time an only if you are in a real pinch and have no other meter available to you, then you might use the Power Output (P.O.) feature on this rig, keeping in mind there is a control on the back of the transceiver to adjust the sensitivity of the circuit for the meter to work. So it's all relative output, in other words the meter has no real meaning at that point other then to show you maximum smoke! And we don't want that!  Hope that helps some of the new folks attempting to tune the FT-101. If you would like to save the tune up use this link and save to a folder






FT-101 vs. FT-101S

(Japan low power version)




Other Models of the FT-101 were sold in Japan for the limited power requirements of the Japanese licensee.  To fill this need there was an FT-101S, FT-101BS, and FT-101ES.  These rigs were sold with only one 6JS6C final amplifier tube, with a normal rated power of 10 watts, and  50 PEP.  From the specifications  I can read it appears as though the FT-101S/BS/ES models ran CW power of  20w (A1) and SSB Phone of 20w (A3J) with only 300 volts to the final amplifier stage as per JARL specifications.



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For those amateurs in the states, above you can get a rare look into the FT-101ES

single tube version transceiver. The "ES" model is seldom ever found outside of Japan.




With the addition of the power up kit,

power could be increased to that of an FT-101E





FT-101 vs. FT-101S

(Japan low power version)


Some interesting comparisons of the low power transceiver



FT-101S Single tube PA



High Voltage

FT-101 Vs. FT-101S


Note the 3 Ohm 30w resistor

 in the filament circuit of the FT-101S







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