[Yaesu] 897D off Frequency

[Roger (K8RI)]

On 10/15/2012 2:09 PM, Cortland Richmond wrote:
> 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
> not.

It's far enough off that I noticed the audio being garbled on FM.
On SSB I just tune so the station sound fine and pay no or little 
attention to the readout.  However, with all the control hams have over 
the audio, it's rare for me to be on their frequency using either of the 
big rigs.  One ham turned off his processing and I was able to put the 
5000MP right on frequency, but when he'd turn on his processing, I'd be 
off by several hundred Hz if I made him sound normal.


>
> 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.

I have a good spectrum analyzer to sub for the millivolt meter
Unfortunately I don't have a good frequency counter at present.

More below.
>
> 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?

Close enough that the audio is not distorted from being low (or high) in 
frequency. On SSB I only care about band edges but the 897D is a backup 
and go rig. It sees little use from either home station. I have a 
FTDX5000MP in the shop and an old Icom 756 pro in the house.  Most of my 
operating is done from the shop which BTW has an interior of bonded 
"barn metal" and all wiring is in surface mount EMT conduit.

I've only seen a couple of responses so I wonder if people are still 
using the digest.  If you do I'll never see the post as anything with 
digest is filtered out before I ever see it.


73

Roger (K8RI)

>
> Cortland
> KA5S
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