What you’ll need: Multimeter, dummy load, Orion programming software (Programmer for Windows or the older DOS software), radio code files for the radio (used when programming; re-uploaded each time the flash memory fills up).
If you are moving the band split (and this is probably why you are here), you also need the SC or SC4 files.
Full instructions follow this silliness…
Step one: prepare and program a personality set covering all frequencies you plan to use the radio on, TX and RX, add 500kc or so to either side and add additional channels so that there’s *something* at 250 or 500 kHz intervals all the way across the range for testing. The reason for this is that the oscillators are multi segmented. Connect a dummy load. Receiver testing using a signal will not be necessary.
The tuning voltage should be 3.5-7.5VDC measured at test point TP201.
TP201 is visible and easily accessible through a hole in the shield (no removal needed). If you’re lucky, multimeter test leads fit right in there such that the hole nicely cradles the plastic shell around the probe end and leaves the probe end sitting right on the nice wide round pad on the board.
TP202 is the modulation voltage test point. Don’t use that one. You’ll chase your tail in circles forever.
The two pots are CV280 for transmit VCO, CV240 for receive VCO.
Now, the crafting of your test file is important. If you study the schematic you will notice that each VCO has THREE additional tuned circuits that can be attached or detatched to it by the CPU. I believe the VCO has four banks (one of the valid states being none of the additional circuits attached). The way I usually do my test file is to put in 250kc steps across the entire range of the radio I want to use.
The synthesizer may lock with the voltage outside of the 3.5-7.5VDC range, but don’t leave it there! Doing so will create a temperature dependent picky son of a @$%*@!!! radio.
As you tune you will notice the voltage will ramp gradually up then drop down suddenly – this is a VCO band switch. I believe you can manually force selection of a certain VCO band in the personality…?
When you land on a frequency where it’s not locking, the radio will flash ERR=0401 NO LOCK and if you’re stuck in a RX no lock, the radio will keep constantly rebooting(??) to try to restore operation. The VCO voltage will jump all over the place in a maddening fashion. First dial in the pot for the VCO until it locks, then worry about getting the voltage in order.
See LBI #38910 for more info (a quick search for LBI 38910 will return it from multiple sites.)