Navman 7100 VHF Radio Microphone Curly Cable

[Colin Stone]

The black outer PVC insulation of the microphone curly cables on my brace of 18 year old Navman 7100 VHF radios are disintegrating, exposing the aluminum screen wrap.

I got replacement 8 core screened curly cables from Kalestead. kalestead.co.uk/cable-design/coiled-cables/

However, on getting into the radio, I've discovered that the microphone positive lead is individually copper screened with the screen forming the microphone negative lead.

The new cables have the usual foil wrap and but just a drain wire.
kalestead.co.uk/cable-design/cable-screening/

Kalestead annoyingly tell me that the microphone wires should be screened - and they have an 8 core with 2 screened wires. Shame they didn't tell me when I originally enquired about an 8 core microphone cable for a marine VHF!!

I also need the JST ZH 8 way male connectors. Tiny and hope I'll be able to crimp the sockets for the male plug with small needle nose pliers.

So, I 'm wondering if I can use the original replacement cables without the individually screened wires?? But I still have to get the ZH connectors.

I think for now a pot of liquid PVC tape.

I've considered new radios, but they don't have the features of a 20+ year old design. And this really should be repairable.

[Hbomb]

I have exactly the same model, with the same problem. I'm wondering if the lead could be removed and covered with heat shrink, I think it might be worth a shot.

[Colin Stone]

I've bought new 8 core curly cords, JST ZH 1.5mm crimps, they are tiny, plugs and the crimp machine. A winter project.

[Flemming]

Hi from Denmark

The same problem applied to me.

In My opinion the Navman 7100 is still worth preserving as it still has all the features needed today. So I made this pdf instruction on how I used a 5mm generic 6 core + 1 screened cable.

I had to scale the document down due to the 2Mb limit, hope its ok.

I forgot to mention, that besides being glued together, there is also a screw hidden beneath the silver sticker.

Best regards
Flemming

[Flemming]

Ohh... about this hidden screw... as I further remember, the silver sticker was just to cover a hole in the outer plastic cover. The screw beneath the hole does not hold the outer cover. So no need to remove the sticker... as I remember.

[Colin Stone]

Well repaired. I did my cables a couple of weeks ago using the Kalestead cables in #1. I was told by another electrical guy that having a single screen round one core was no better than using the shield and drain wire as the earth connection.
And I used the ZH1.5 8 way connectors, crimps and a crimp tool.
In testing all seems to be fine.
But I didn't take any pics etc.

[s/v Jedi]

Yes you-must- use the crimp tool, not needle nose pliers.

Remember, always use the proper crimp tool. When you don’t have it you need to buy it.

[Colin Stone]

Originally Posted by s/v Jedi

Yes you-must- use the crimp tool, not needle nose pliers.

Remember, always use the proper crimp tool. When you don’t have it you need to buy it.

Note - I wrote this in #6:

And I used the ZH1.5 8 way connectors, crimps and a crimp tool.

[Flemming]

Hi Colin

It was nice too to hear that you finalized your vinter project, one more radio saved - smile.

My problem was that I could not find a curley cable with that many cores, an outer foil and an individually screened microphone core, - as the original.

About the "5 mm generic 6 core + 1 screened" curly cable (total 8 connections in the connector) , - then the screened core is for the microphone. The other 6 cores are control wires for the 6 bottoms on the microphone, one core for each bottom in order to detect an on/off push at the bottom. It is not that important that they are schilded with an outer foil.

In a case where only one shield/foil covers all the cores, my guess is that the one in the receiving end might hear a little "click" if the bottoms are pressed during transmitting. This is because a little current will flow in the core for the bottom and this core runs along the core for the - not individually screened - core for the microphone, which then has the potential to pick up a little spike from the current. But this is very theoretical and will most likely not happen and who will press the bottoms on/off during speaking!

Best regards, Flemming

[s/v Jedi]

Originally Posted by Colin Stone

Note - I wrote this in #6:

And I used the ZH1.5 8 way connectors, crimps and a crimp tool.

Yes, good job. I wrote that because the first post suggested using needle nose pliers and readers may think it’s okay to do that.

[Colin Stone]

Thanks Flemming,

I agree - I couldn't think of any reasons to press the buttons, other than pressel, when making a transmission!! I do get a start/stop Tx click at the Rx station - but I couldn't tell the difference between a radio with old vs new mic cable.
I had found 8c2s - https://www.ebay.co.uk/itm/133833735983 at £50 but the plain foil/drain 8c is not listed. I did note that a 6c Yaesu cable has no apparent screening at all and transmits at similar frequencies to marine VHF.

Best, Colin

[Colin Stone]

I also found the service manual last year. I don't think 2 of the microphone wires, 7 and 8, do anything, so a 6 core cable might be OK.
Page 106 at link:

https://elektrotanya.com/navman_mari.../download.html

[Flemming]

Hi Colin

Thanks for your comment and report about the trial, that was interesting.

I also downloaded the Service Manual, which I could have used beforehand. From there it's shown that, - besides glued to the front panel, it is the 6 screws in the bottom of the cabinet which holds it together. And now when I see the diagram at page 106 and the working principle of the microphone, then obviously pin 7 and 8 are not used! It was my faulty assumption that there was one core per button. Yes, it could have been really nice to have that service manual beforehand - smile. By the way, this unit is special in the way that it has no outer microphone connector, so the only way is to disassemble it. The microphone cable has part number 08-H236601-A00 in the Navman Service Manual.

I too have seen that Icom, and also Yeasu, uses cables that are not screened... they may use another system, maybe balanced microphone cables.

Best regards, Flemming

[Colin Stone]

Hi Flemming,

I've just found a NL firm that can reprogramme Navman 7100 to disable the VDES analogue channels for digital comms. https://www.vrmmarine.nl/
There seems to be a serial PC port through the 8 pin DIN plug that has the GPS connections. Manual Page 9 diagram.
It can't be that difficult - can it??