A problem from the Australian Antarctic Division regarding their fleet of Codan 9360 radios

[norazzzzz]

They use the radios in all of their Antarctic Bases. It seems the issue is that when they use a sloping wire antenna in the Antarctic, the radios tend to reset to Upper Side Band and 3 MHz frequency. This does not happen in Australia. I know that the humidity levels are extremely low in Antarctica and I suspect that static build-up on the sloping wire antenna is the problem. This is a serious problem because it is causing a loss of communications to the outposts who don’t realise that the radio has reset itself.

How to solve their problem so that when the radio does reset it will be on Lower 4 MHz Side Band which is the Antarctic Division's standard radio frequency.

 

[RFI-EMI-GUY]

It sounds like a grounding and bonding problem and lack of a device, shunting resistor and gas discharge tube to bleed of the static. The equipment itself may have sustained damage from repeated surge. Somehow the voltage surge is entering the radio through some circuit or accessory. Perhaps the microphone, control head and radio unit need to have better bonding and shielding.

Have you contacted CODAN? it seems they should be concerned as well that their radios are susceptible to this.

 

[a417]

This is a serious problem because it is causing a loss of communications to the outposts who don’t realise that the radio has reset itself.

I agree with @RFI-EMI-GUY that CODAN should be made aware of this (if they weren't already), but that does not take away from the responsibility of the operator to make sure that they are correctly adjusted prior to key-down.

I don't know if they not looking at the control heads to make sure they are configured as appropriate, the heads are hidden/not always visible from mic location, or it's apathy...but the operator is not completely without blame here.

 

[TampaTyron]

Additionally, it MAY be an issue with dirty power. Are these radios on UPS or battery backups? The above stuff is more likely, however. TT

 

[RFI-EMI-GUY]

It looks like that is a very old model radio so support from CODAN may be minimal.

Codan 9360, Codan 9350

www.greenradio.de

I suggest Motorola R56 as a start for grounding and bonding. However bleeding off the static charge from the long wire antenna will require some field experiments and design effort.

Gas discharge alone will result in popping noise as the gas discharge device will become a relaxation oscillator. So an appropriate sized bleed resistor will be needed. I would also suggest that the radio "shack" be screened with a grounded conductor on floor and walls so that occupants touching the radio are at same potential as the radio when the enter the room.

As far as the radio itself being critical to life safety (I presume), I question the use of such an antique. However it may be a time proven product. Perhaps the radio programming firmware could set the default channel and mode to that normally required for the net?

I just watched a strange SciFi movie called The DustWalker and the radios looked like same ones.

 

[Thunderknight]

Ia the antenna configuration IDENTICAL in both places? Otherwise anither thought his RF getting back into the unit and causing “weirdness”.

 

[k7ng]

You have no idea how hard it is to get a good RF ground in most of Antarctica.

 

[TampaTyron]

Come on man, get a cup of dirt and put the ground wire in it. Problem solved! TT

 

[k7ng]

Whatever you say.

 

[k7ng]

The cup of dirt might be the hard part...