Calibrating the Kenwood TR-9130 with your HF rig
The Kenwood Service manual requires that a frequency counter good for 130Mhz plus be used to calibrate the PLL of the Kenwood TR-9130. I don't have one, but I do have the trusty TS-850S, so I tried to figure out a way to adjust the vhf all mode transceiver using the HF rig.
Please read these and follow instructions in its entirety.
There are two frequency determining sections of this rig. One is the carrier unit and the next is the PLL 14 mhz oscillator (which generate the 0 to 9.9khz spacing of the PLL).
Measuring the frequency of a carrier with an HF receiver can be tricky. So I deliberately tuned the receiver 400 Hz away so there would be a beat note if I monitor the signal whose frequency I was interested in measuring. I can hear a beat note but how do I know it is precisely 400 Hz? That is where the internet comes in. You can download or hear samples of 400Hz on many sites. If you listen simultaneously to the internet sample and the sound coming from the hf speaker you will note that the beat note can be zeroed out as the two frequency comes close and eventaully synchronize. You will note this "motor-boating effect when you either tune the hf away or near the signal or vary the frequency of the signal under test by adjusting a capacitance or resistance (in case of varactor circuits).
Part 1 We use the hf as receiver and monitor the carrier unit output.
Attach a short piece of wire (to act as probe) to the center conductor of a coax connected to the HF receiver. Dangle this wire in the vicinity of the carrier unit.
You should receive a strong signal. Offset the receiver by exactly 400 Hz. Surf the internet and google 400 hz tone and listen to the sample. The WWW sample should zero beat with the tone coming from your hf speaker.
You should adjust the carrier unit, using the table below from the service manual below (frequencies are actual carrier output, you must tune the receiver 400hz away) :
Adjust the trimmers you while listening the beat note between the WWW 400 Hz sample and the sound coming from the hf speaker. You should be able to sync within a few Hz.
After finishing the Carrier Unit adjustment. what remains is the main PLL. The service manual require a 130 + mhz frequency counter which I do not have, so we devised a workaround.
Part 2
After the CAR unit you must adjust the PLL 14 MHz oscillator. Instead of acting as a receiver. the hf will now be use as a signal source. We shall transmit on ten meters while we monitor the 5th harmonic with the TR-9130.
Set the TR-9130 at 144.9999 USB. Your hf should be set to 10 meters, AM or CW with this frequency: (144.9999 +.0004)/5=29.00006MHz . The ".0004 is" the 400hz offset.
What this mathematical equation is trying to say is that in order to hear a 400 hz beat note on the tr-9130 speaker, it has to receive a 144.9999 + 400Hz (= 145.0003 MHz) signal assuming the receiver vfo is set to 144.9999 . And 145.0003 would be the fifth harmonic of a 29.00006 Mhz signal, which our hf transceiver can easily produce so we set the hf to this frequency.
Put a short piece of wire at the TR-9130 antenna input as a rx antenna. Connect hf to a dummy load. While transmitting a low level carrier, You will now adjust TC1 for zero beat between the TR-9130 speaker tone and the WWW 400hz sample tone played back on your computer's speaker.
Tune HF rig to (145.0000 +.0004)/5=29.00008MHz and adjust VR1 for zero beat, similarly.
On the PLL board, the 14 mhz oscillator alignment is pretty tricky. you will know you have done everything right if there is a normal change in pitch of a received carrier as you go through 100Hz steps, particulalry from say "4.999.9 to 5.000.0 while on sideband receive. If you notice a jump in pitch greater than with an expected 100Hz vfo change, you have not done the adjustment right. Proper setting of TC1 and VR1 apparently insures linearity of the 14 mhz VCO which controls the 100Hz steps.
Do not attempt this before understanding the underlying principle of your Kenwood TR-9130 PLL system. Do not attempt this if you are unqualified or feel nervous. It is possible your tool may slip and damage the radio. Extreme caution must be exercised as adjustments are done with the radio turned on. 73 DU1FV
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