APX7000 Out of Band

[willbird287]

I've been toying with the idea of buying an APX7000 for a while, but I would like to access a frequency just 1 Mhz outside of the UHF band that it covers. Currently with every radio I use, it's no big deal to push band limits by a bit.

Wondering if anyone who currently has an APX and CPS has successfully gotten theirs out of band (even if just for experimentation)?

I'm particularly curious if the same tricks apply to the new APX CPS as did for the ASTRO and ASTRO25 CPS?
Has anyone even tried a quick search for band limits?

--Will

[rc50won]

It appears that as of the release of version 4 firmware, out of band is no longer allowed.

Marshall

[willbird287]

Anyone else have any experience with out of band?

--Will

[n7maq]

Anyone else have any experience with out of band?

--Will

It will not work on the ones I have seen and tested OOB.
Jim

[Trans Tech]

My version CPS 4 will allow me to type frequencies out of band in the APX. I'm guessing the out of band mod maybe embedded in the firmware?

[willbird287]

Yea, the software allows it if the correct box is checked, and the radio will accept the OOB frequency, but when you try to go to that channel you get an error on the radio. I'm thinking it's either disallowed in the codeplug somewhere or in the radio's firmware...or somewhere deep in the cps. I'm hoping someone better at software than I am can find out more and get it working again!

--Will

[lemish]

You need to use Expert View and find the check boxes to allow invalid frequencies in the code plug.

As far as the error displaying on the radio - there must be a way - anyone???

[Fuel4300]

CPS 5 with R05 firmware also gives me a solid tone and 'Invalid Rx Freq' on the screen.

I spent a while poking around APXFamilyCPS.exe with Hex Workshop and I can find a few references to band limits - 136MHz and 512MHz - but no mentions of 470MHz which is the one I would like to modify.

I modified the lower limit - 136MHz - and the CPS still rejected it unless I checked the 'Allow Invalid Frequency" which allows me to enter it but I get the same error on from the radio.

Anyone have any better luck?

[willbird287]

I'm almost certain that the band limits are stored either in the codeplug or radio firmware. The CPS allows you to program out of band, and clearly it's programming properly into the codeplug and loading into the radio. (I went a step further to test this theory by programming an in band RX frequency and out of band TX frequency. It would receive fine but when PTT was pressed, a similar "Invalid Tx Freq" was displayed.)

Apparently with R02 firmware you could access out of band frequencies with no problem, and then R03 stopped that. This leads me to believe the band limits could be stored in the firmware. With the new firmware, the band limits were tightened up.

The only other alternative I can see is if the new firmware changed the way the radio checked to make sure the frequency it was trying to tune to was allowed (by telling the radio to check against the band limits in either the firmware or codeplug to confirm it's a "valid" frequency).

I've never hex edited in RAM before, so I've been trying to find someone who can lend some expertise and technical assistance while I poke around. The last thing I want to do is brick my APX. Is anyone around who has extensive experience with ram editing codeplugs willing to work with me on this project? PM me please.

--Will