Modifications for the Yaesu FT-101

FT-101 series, convet 11 meter to 12 meter
Replace finals in FT-101E
FT-101 Mod for 30-meter (10MHz) Transmit
Audio hum in Yaesu FT-101 ZD

 

  FT-101 series, convet 11 meter to 12 meter  
     

Converting 11 Meter band to 12 Meters for the Yaesu FT 101 series ..

Although this procedure hardly qualifies as a "mod" (too easy), it is certainly useful for the FT 101 series owner. Conversion to the 12 meter WARC band is as simple as replacing a crystal. The 11 meter xtal is replaced with a 30.52 Mhz 3rd overtone xtal in a HC-25/U holder as specified in the FT 101 series maintenance manual. No other modifications are necessary as the new band is close enough to the original that the current components work. To replace the xtal, remove the oop cover and find the xtal board located at right front of the rig.
Xtals marked xxxx are standard while oooo are optional on some units. X5, for the 11m, band is an option and may or may not be installed.

 
        10B     xxxx    xxxx    80
        10C     xxxx    xxxx    40
  JJY/WWV (1)   xxxx    xxxx    20
        160     oooo    xxxx    15
                xxxx    oooo    < X5 the "11 meter" socket
                ....    xxxx    10A

The xtal was ordered from Marden Electronics (800-222-6093) although it is probably available from the other companies which offer this type of item. I'll skip the business details here, but it is cheap. I found fat fingers a hindrance when yanking the old and insterting the new so I used a hemostat (narrow nosed locking type device with "seconds" often found in hardware stores, etc.). After checking with a local ham who monitored my transmissions to make sure I was where I thought I was, I was in business with 12 meters for my FT 101B.

How'd it go ?? After warming up the rig, I spun the dial a bit on what has been a mostly dead band this summer. The first station I heard was a little weak .. AA5QC .. no it's A35QC. I had no idea where that was, but I gave him a call. It turned out to be JF1WQC vacationing in TONGA, my first African contact and a 59 report at that! So here's an easy way to add a WARC band and open new possibilities for DX adventure with your FT 101 series rig. Please let me know if you have any additional feedback or comments on what has to be one of the easiest "mods" ever.

(1) This is another story .. note that it is a receive only band for 10 Mhz .. for now. See Page 70 of the Nov 83 issue of 73 Magazine if you can't wait.
  Replace finals in FT-101E  
     

There will come a time when the finals in your FT101E will need replacing. These transceivers were originally equipped with 6JS6C tubes manufactured by NEC.
This tube's properties are slightly different from the 6JS6C tubes available today from American tube manufacturers. By the way, don't bother looking for tubes made by NEC. They got out of the business several years ago.

In order to use the "American" variety 6JS6's, a simple modification to the neutralization circuit must be made to the final section of the transceiver.

The modification consists of replacing the fixed value 100 pf 1000 VDC mica capacitor with a 10 pf 1000 VDC mica capacitor. This capacitor, C125, is in series with the 10 pf variable neutralizing capacitor off of the plate circuit.

If this modification has not already been completed on your rig, be sure to use a mica or silver mica of at least 1000 VDC. Do not substitute a different type, because the heat in the final compartment will change the value, and your tubes will fail prematurely. Also, be very careful to keep all leads short and in exactly the same orientation as the original capacitor.

Before reneutralizing, open the variable neutralizing capacitor all the way to minimum engagement and follow the neutralizing instructions in the manual. While dipping the plate, remember to adjust the neutralizing capacitor for equal value meter reading peaks (IC position) on both sides of the dip when tuning the "Plate" control.
  Audio hum in Yaesu FT-101 ZD  
     
Author:
I have always liked transceivers with tubed final stage, for several reasons, but mainly because it is nice to hear from your correspondent: - you have a very good modulation, ... it sounds different, ... the tubes' job is noticed.

In addition of that I have to say that tuning these transceivers is not a trouble for me, and also that up to now all the servicing needed by my3 tubed transceivers ( 2 Yaesu FT-101 ZD and 1 Yaesu FT-102) has been performed by my self.

One day I noticed in one of the Yaesu FT-101 ZD a little hum which could be heard at minimum volume level and when the radio was switched to transmission with the PTT. Tt wasn't a great trouble but when you want to have things working as better as possible you are forced to try finding the problem.

The first suspicious were the electrolytic capacitors of the power supply, and they were all replaced by new ones, even the pair of 200 uF, 500 volt, on the high voltage rectifier, but unfortunately the hum was still there.

Then the following step was to checkthe final audio amplifier located in the PB 1964 af unit, replacing the output module UPC2002, but no improvement was obtained.

After checkingthe parts around this module I could verify that the problem was in the 2 wire shielded cable connecting the input of Q01 (UPC2002) to the potentiometer of volume in the front panel.

I desoldered this 2 wire shielded cable at potentiometer end and connect there, two new 1 conductor shielded cables, soldering together the braids of these wires at the af board end to a good ground point, for instance to a solder lug inserted in the screw fixing the UPC2002 to the board.
Then I desoldered one end of the resistor R06 4.7 K and the negative end of C07 1uF and soldered there the corresponding wires from the potentiometer

After this operation the audio hum was removed.

I suppose this hum could be picked up by the original shielded cable along its way to the volume control