[Yaesu] 897D off Frequency

Cortland Richmond ka5s at earthlink.net
Mon Oct 15 14:09:40 EDT 2012

On  Mon, 15 Oct 2012 01:30:08  Roger (K8RI)" <k8ri at rogerhalstead.com> :
> My 897D is showing it's off frequency by 2KHz on two FM. IE the display
> reads 147.002 for it to be on frequency for both transmit and receive.
> Is there a way to correct the readout?

This is a common complaint, though usually on SSB,where it is more 
obvious.  At a specified 4 PPM after warmup, , the 8X7 family can be as 
much as 588 Hz off and still be in spec at 147 MHz.  You can adjust 
TC5001 on the reference oscillator board to bring it into spec if it is 

This is best done using a frequency counter per the Yaesu manual (from 
the FCC Web site):

Local Oscillator Adjustment
Reference Frequency Adjustment
a. Connect a frequency counter to TP1032.
b. Adjust the trimmer capacitor (TC5001) for 67.875000MHz ±5Hz on the 
frequency counter.
c. Connect a RF millivoltmeter or an oscilloscope to the J5002 2pin 
(TP1032) and confirm that
the output level is at least 70mVrms or 200mVp-p.

Done properly. the above requires a counter accurate to about .73 PPM.  
Step C may not be needed.

Alternatively, if you can inject a 1 KHz (to make it easier) into the 
data jack -- or couple it to the microphone from a speaker or headset, 
you can adjust TC5001 by measuring the transmit output with a counter.
The adjustment will touchy.

Set the radio for 147 MHz upper sideband mode.  If using the rear panel 
data jack, be internal menu "38 DIG MODE" is set for User-U.

Use only enough tone input to produce the output needed to drive the 
counter; do NOT connect it directly to the output connector, but couple 
a small amount of RF to the counter; there are number of ways. This can 
sometimes be done by using a tap made out of a coaxial T connector with 
the center pin removed from the common side, and adaptors as needed. A 
sensitive enough counter may only need a coupling wire or loop placed 
near the coax from the rig to a dummy load, but you may need more RF to 
use this method.

With 1 KHz going into a rig set for 147 MHz USB, you SHOULD see an 
output on 147.001 MHz

Adjust TC5001 to achieve that.

Accurate calibration if done in a cal lab would require four times the 
accuracy asked asked of teh radio. If we want to be within 20 Hz, for 
example, we'd need to measure 147 MHz to within 5 Hz Hz. That is quite 
difficult.  How close do you want to get?


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