Ranger RCI-69VHP (EPT690012D) - Trimpot VR15 and testpoint TP9 - what are they for?

[CrazyFin]

I have read through the very good threads many times about the alignment of bias of the RT1 (IRFZ24NPBF) MOSFET's on the Ranger RCI-69 base as well as the alignment of the MOSFET's on the Anytone 6666.

Two questions:

1. When I look at the schematics for the RCI-69VHP (EPT690012D) there is a trimmer pot labeled VR15 but it is not mentioned at all in the alignment procedures. The center pin of the VR15 trimpot goes (via a resistor R271 and a diode D105) all the way up to connector J3 and the pin labelled MM. However, according to the schematics there is nothing connected to pin MM on connector J3. Other pins on J3 (GN, MT and MS) are connected to the S/RF & SWR-meter.

2. There is a test point labelled TP9 (near Q52) on the schematics but the alignment procedures does not mention anything at all what this test point is used for?

I have attached the schematics in PDF-format here and a JPG-picture of the alignment locations.
(I could not find a files section where to upload files?)

 

[BayouRadioAmplifier]

just drinking my morning coffee here, and took a peek.
that circuit adjusted by VR15 is the positive going
modulation level from the series modulator ouput.
so MM must be for Modulation Meter.

 

[CrazyFin]

Aaah but of course and that explains why the pin MM on connector J3 is not connected at all.... the RCI-69VHP does not have a modulation meter....

 

[CrazyFin]

Following up on this thread and I have done some reading back and forth but can not really find out what can be measured at testpoint TP9 which is at the base of Q52 and after IC9?

Is it to measure the base voltage of Q52 on the output of IC9 TX mixer RCI-6130A but for what reason?

 

[BayouRadioAmplifier]

again - just drinking my morning coffee here, and took a peek
at the schematic.

TP9 is at the signal path on the way to the transmitter RF
amplifier output circuitry.

I would say this test point is used at the factory when the new
radio is tuned up, L40/42/43/44 around mixer IC9.
Everything would be way out of tune and there would be
low signal levels.

 

[CrazyFin]

Ah that explains why TP9 is not mentioned in alignment procedure.

If mixer IC9 would have to be replaced for some reason then one is kind of stuck in the dark without knowing how to tune L40/42/43/44...

However, I guess the should just be tuned for maximum output when monitoring signal on TP9 on scope or spectrum analyzer?

 

[brandon7861]

The service manual for the RCI6300 f150 says to adjust those 4 cans for max power and minimum spurious with L40 and L42 balancing power between ch1 and ch40. However, that manual says to measure at the antenna jack. Its TP9 is a different thing.

Just a guess, maybe they used that location so checking for spurious emissions did not include those caused by the finals. There is a service manual for the 69 base for sale on one of those radio sales websites somewhere, but I am not sure if someone has scanned it yet. I couldn't find it.

 

[CrazyFin]

@brandon7861 Thanks for the reference to the RCI6300 F150!
I looked into that service manual and all clear now.

RCI6900 F150 service manual and schematics found at the usual place:

Ranger RCI-6300 F150