FT-101/B/E/F Carrier Frequency Alignment Instructions
13 April 2006
Here is something you may want to add to your FT-101
instruction/maintenance manuals:
As another ham pointed out to me, neither the Instruction Manual
nor the Maintenance Service Manual for the FT-101 series of radios
seem to include alignment instructions for setting the
carrier-insertion frequencies for USB, LSB, AM/CW. Normally,
they don’t need re-alignment, but sometimes they can go out if
someone has adjusted them hoping to correct some other problem
with the radio. If these three oscillators are misaligned,
they can cause the quality of the transmitted and received
audio to sound bad. Also, a misaligned carrier frequency can
leave an annoying carrier on your transmitted signal.
Other Yaesu radios include alignment instructions for these
oscillators. My FT-101ZD, FT-901DM and Tempo One include them;
however, the information is also missing in my FTdx-560 manual.
If you have a digital frequency counter with a resolution of
100 kHz or better, and you can find the right sampling point,
you can get these oscillators pretty close by simply using the
frequencies printed on your schematic.
However, to do it properly, they really should be set to the
response curve of the crystal band-pass filter being used.
Not all of these filters are the same. Aftermarket filters
often have steeper skirts or a narrower pass-band than OEM
filters and all of them can change slightly as they age.
Here are the cut-and-paste carrier frequency adjustment
instructions for the FT-101/B/E/F circuits as adapted from
the FT-101ZD manual. The parts in brackets are where I made
the changes from the original FT-101ZD manual to fit the different
IF frequency, part numbers and circuit layout of the FT-101/B/E/F
series. Notice that the carrier adjustment can mess up the carrier
balance on sideband as well, so don’t forget to make that your
final adjustment.
* * *
A. SSB Carrier Point
1. Tune up the transmitter on 20 meters,
LSB mode, into a dummy load. Apply a
1 kHz audio signal to the microphone
input, and adjust the audio generator
output until the transmitter power output
is 60 watts, as indicated on the dummy
load wattmeter.
2. Shift the audio generator output
frequency to 300 Hz, without changing
the output level. Adjust [TC3] for a
power output reading of 15 watts on the
wattmeter.
3. Shift the MODE switch to USB.
Adjust [TC2] for an identical 15 watt
reading on the wattmeter.
4. Recheck the LSB adjustment, as
well as the carrier balance adjustment,
after performing the carrier point
alignment. The background noise,
when switching between USB and LSB,
should not change.
B. Carrier Balance
[This description is essentially the same
as the one in the FT-101/B/E/F instruction
and maintenance service manuals, so you
can just insert that part here.]
C. CW Carrier Point
1. Connect a frequency counter to
[a test point on circuit board PB-1183,
at the common junction of C11, C12,
R8, R9, D3, and D4. The lower end of
C11 should be the easiest tap point.]
Place the MODE switch in the TUNE
position.
2. Adjust [TC4] for a frequency counter
reading of exactly 3179.3 kHz.
3. When using the optional CW filter, a
substantial loss on transmit, when in the
[CW] position, may indicate the need for
adjustment as indicated in steps 1 and 2.
* * *
If you don’t have a calibrated audio signal generator,
there seem to be a lot of software programs on the
internet that use the soundboard in a personal computer
as a calibrated audio generator.
If anyone has any comments, suggestions, additions or
alternative methods of carrier alignment for these radios,
let me know and I’ll try to do an update to this file from
time to time.
— John (N0BUP) (jpkiljan atsymbolthingy yahoo.com)
(file: 101CarrierAlign.doc)
Shack of VK2KMI 