Kenwood TS-480 and TM-D710G MARS Mods and Upgrades

I always photo document any changes I make to critical equipment and electronic equipment in particular. I performed some upgrades and mods to my recently acquired Kenwood mobile transceivers and thought I'd share.

NOTE 1: These modifications are being made to US version of this equipment. Non US versions may require different procedures and parts.

NOTE 2: The MARS/CAP Mods allow the transceivers access to additional frequencies that you are only allowed to monitor unless you have authorization to transmit. It is your responsibility to know which frequencies on which you are authorized to transmit. For information about the Military Auxiliary Radio System please read this article: Military Auxiliary Radio System - Wikipedia

TM-D710G

• MARS/CAP mod
• Same process for the TM-D710 and TM-V71

Here is where the modification is performed:
View attachment 56953

This mod is done by removing a green jumper wire and a very tiny surface mount resistor. I removed the wire by heating up each end and pulling the wire away like is shown in the video that follows.

The resistor was removed using just the tip of my soldering iron by heating one side then quickly moving to the other side and the resistor then stuck to the tip of my soldering iron (from the surface tension of the molten solder) as I pulled it away.

I then went back and reflowed the solder making sure the pads were well rounded and shiny and no micro solder antennas left over from pulling the wire or resistor away.

I tossed the resistor since it likely cooked on the end of my soldering iron before I scraped it off on my wet sponge, but if you need an OEM Kenwood green jumper it is available for USD $29.95 plus USD $35 shipping and handling.

The jumper and resistor to be removed:


And after:


Not my video, but shows the modification:


TS-480SAT/TS-480HX

• MARS/CAP MOD
• TCXO MOD
• 1.8 KHz SSB Filter MOD

MARS was discussed above. The TCXO reference crystal mod provides a more stable and precise reference for the radio's VFO, especially in high temperature environments. The 1.8 kHz SSB filter allows you to operate on a narrower bandwidth and more effectively use your TX power when you are close to max. Special thanks to @BTPost for the kindly providing the 1.8 kHz SSB filter.

The locations where the mods are performed:


The MARS/CAP mod is performed by removing the shield that covers the resistor that needs to be removed and then removing the surface mount resistor using the same technique as was done for the TM-710G above. Do not forget to replace the shield when complete.

Installation of optional filters and the TXCO reference crystal is covered in detail towards the end of the owner's manual. You do not need to recalibrate the radio after installing the reference crystal - it is purely a drop in a go process.

To install the filter and TCXO crystal modules you need to remove the daughter board where they will be installed:

• Using the tip of a screwdriver or similar flip up the two white connectors on either side of the daughter board
• Remove the three screws holding it in place. I like to remove in this order to prevent any stress on the board when I loosen the connectors.

The filter can be installed in either of the two filter option locations. I used the OPTION FILTER 1 location. Before I placed the filter on the board I placed a small amount of flux on every solder pad that will be used. Even though the solder I use contains flux this allows the solder to "stick" to the pad quicker and reduces the amount of time the components are heated.

The TCXO crystal must be mounted with the adjustment hole as shown. The filter modules may only be mounted one way due to their pin layouts. When you mount the modules use the tip of a small screwdriver to bend the shield tabs to hold the part in place while you solder and to help make a better connection. The crystal module should be bent just enough to hold the part in place.

EDIT: Don't forget to solder the shield tabs of the modules to the PCB.

Solder the modules using enough solder to make a good connection and be careful particularly with the filters to prevent a solder bridge from causing a short. After soldering I removed the flux with isopropyl alcohol and a q-tip. The flux itself should not cause an issue, but it won't help anything and I like to keep my circuit boards clean. Next I visually inspected for solder bridges using my old guy magnifiers. A strand ofsolder thinner than a human hair can cause disaster so always inspect very carefully. I also tested resistance to make sure that pin was not shorted to any other as some are very close.

Replace the daughter board by reversing the steps used to remove it above. Make sure you double check that you snapped the connectors back in place before you replace the cover.

If you install the TCXO crystal then you need to do one more step. There are a pair of resistors that have an exposed lead that mus be cut. If you don't cut these leads the radio will use the standard crystal instead. The resistors are circled in red in the photo above and are the only ones in the radio that have exposed leads.

In the videos I watched the leads were simply snipped, but this leaves you open to a potential short as they are fairly long. I started by snipping the lead at the resistor side, then held the lead with a small pair of needle nose pliers while I snipped the other end close to the circuit board. This prevents the lead section from dropping some place you don't want it and by removing the whole lead there is no chance for a short.

While I've gone into quite a bit of detail in this write up, these modifications are quite simple and quick to perform.

 

Ah yes, reminds me of the CB Days when if you knew what to do you had 40 Channels in a few minutes of work. Not that I would ever be involved with anti FCC Recreational Mods.

 

Wasn’t there a song that went “40 watts 40 channels, and only idiots on...”? CB is still relevant for monitoring and information gathering during SHTF.

 

Nope, the first were 19 channel. Just as TESLA has the hidden storage capacity the Cobra had already set up the production lines for 40 Channels and sold what they had as licensed 19 channel.
If you knew what to do then it was simple to increase some of the 19s to a 40.

Other tricks with the SSBs.

 

Yup I still have one or two from cleaning out in laws homes.