Converting Pyramid SVR Vehicular Repeater for Amateur Operation Part 1

I recently purchased a Pyramid SVR-200U with the sole purpose of using it as a cross band repeater for the mobile.
I have 900/220/144/and 440 in the mobile with the 440 being an XTS 5000 in an XTVA adapter, so the idea being if I put a DB9 switch on the Pyramid I could then flip the switch and cross band UHF to any of the 3 bands simply ejecting my XTS when I’m ready to go.

There are however a few hurdles that will need to be managed before you can enjoy the SVR on the amateur bands.
The two main issues you’ll find are:

  1. The software does not allow out of band frequencies to be entered
  2. The SVR PLL may not lock on a given frequency without going through the tuning procedure.

In this post we’ll go over the process that I used to patch the software to allow out of band frequencies to be entered and in my case it was enough to tune 446.6125Mhz which is likely what I’ll use as my link frequency.

When you attempt to program a frequency not supported by the software you’ll be greeted with this amazing error.

This error is actually vary import as it gives us exactly enough information to patch the software for out of band use.
I prefer to use x64dbg for this purpose but you may use other debuggers if you wish.

When you first open the debugger and load the SVR CPS you’ll see the following

Notice the play button and the title bar, you’ll want to hit play until you see you are in the SVR200CPS module.

From here you’ll want to right click in your main window and search for string references in your current module.

We then search for the string (text) we saw in our initial pop-up that told us we couldn’t go out of band. You should find four instances of this string, one for each band supported by the software.

Now you’ll want to double click on the first one and you’ll see the following

Scroll up a little bit and you will find the function that makes the decision on whether your frequency is within the band limits or not.


Looking at the above you’ll see an assembly instruction of ‘JE’ which means “jump if condition is met” In other words in our case. Jump if frequency entered is within band limit, if it is it’ll program it but if not it’ll continue onward and show the error message preventing you from going any further.

To fix this we change the ‘JE’ condition to a ‘JMP’ condition which will always jump over the error and trick the software into thinking any frequency you enter is within the band limits.

Simply double click on the instruction and make the change.

After you have done this you’ll want to go back to your resources tab and repeat for the remaining range strings.

The final step is to save the patched file and program your SVR without any band limits!

Ensure all your patches are selected and hit patch file, then just save it with a “.exe” extension on your file name and it’s ready to go.

 

Next time I hope to go into the process for tuning this radio, however if you’ve no time to wait just grab the service manual online and get to work. The process should be no different than listed.

If you don’t have the tools to do so test the high and low ends of the band (within your authorized frequencies and reasonable within the band plan) and see where it locks.

If the far right light is flashing your PLL is out of lock, try another one.

I’ve uploaded a video tutorial on this topic as well.

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About the Author: KR0SIV

Avid Amateur Radio Operator and Experimenter.