Astro Spectra

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Info on the Astro Spectra

This is for the Spectra CPS 174000000 MHz band edge in hex. Change it to 403A690D 225,000,000 MHz



You can't do this on an old code plug, it needs to be read from the radio.

Codeplug notes

There's some notes on the codeplug as a srecord here. This might be useful.

Use the mototools program to pull out the code plug.

Now you have the binary.

The frequency tuning points control the radio for when to switch the VCOs. I verified this by rewriting the Transmit 150 MHz one to 151 MHz and then tuning to 150 mhz in the radio and transmitting. This did not move the aux lines. At 151 mhz it switched the aux lines.

This means the CPU uses the frequency points as it's switch over points, so we can use that for changin it to 220.

The RX VCO has the same thing and I've moded it to 150 from 166.15 to verify.

The high RX and low TX range use the same VCO. This will be a problem for 220.

Checksum on blocks

The code plug is divied up in to blocks.


where nn is the length of the block not including checksum nn= len( nnttddddddd)

tt is the type of block
dd is data in the blcok
ck is the value of checksum(8) of the block including the header minus 0x55.

Some blocks use a 2 byte length

These use a checksum 16 at the end of the in the CKSM data.  
This is the checksum(16) of the block including the header, with 0x5555 subtracted from it to get the CKSM.

I've seen the 09 block have a not valid checksum as read from the radio, but corrected per the above it goes back in the radio fine.

Rx Vco

The RX vco locks up to about 190-195 MHz


The TX VCO locks up to about 176. Step size was one mhz so it unlocked at 177 MHz. At 176, it made 120W still.

Perhaps the PA will work up to 220?

800 MHz to 900 MHz Conversion notes

The AS lacks the support of hear clear, No idea how it would work if we could get it hooked up.

The Codeplug and tuner/programing software does define a band for 900 MHz, but it's not setup with valid values. This will need to be edited.

W3 Hand Held Control Head notes

This normally needs a long Y cable to plug into the right hand side of the high power radio. There is a DB15 accessory connector on this and it plugs into the ignition sense and other lines.

If you just want to plug the HHCH into the radio directly, you need to add a jumper JU52 on the control head interconnect board and then jumper 20 and 3 on the right DB 25 connector. This will enable the ignition sense line on the right db25 connector and the HHCH will no be able to power cycle the radio.


File:Astro Spectra CPS

Other Software

MotoTools1.3.0.0 - allows you to read and write the binary codeplug.


Astro Spectra Basic Service Manual

Astro Spectra control head and interconnect board service manual

Astro Spectra control head and interconnect board service manual

Software I've written

A decoder for binary codeplugs