astro spectra mic extension? and antenna spacing?

[SoCalRescue]

Hey all.

1) is there a cable that will extend the microphone to the W9 control head and if so is there a part number/ someplace I can buy this? I mounted my w9 up where the sunglass fold down container normally goes abd I don't want the Mic hanging down. Id like the Mic down on the console where it normally goes but need an extension from the back of the W9 to the console.

2) is there a recommendation for antenna spacing? I have a VHF transmitting at 110 watts and my xtva with a UHF antenna how far apart should these be and what's the reccomended spacing if I am eventually going to mount 2 uhf antennas, 1 800mhz antenna, 1 vhf and possibly a lowband antenna. Should these be certain distances from eachothee? This is on a dodge charger

[Jim202]

Hey all.

1) is there a cable that will extend the microphone to the W9 control head and if so is there a part number/ someplace I can buy this? I mounted my w9 up where the sunglass fold down container normally goes abd I don't want the Mic hanging down. Id like the Mic down on the console where it normally goes but need an extension from the back of the W9 to the console.

2) is there a recommendation for antenna spacing? I have a VHF transmitting at 110 watts and my xtva with a UHF antenna how far apart should these be and what's the reccomended spacing if I am eventually going to mount 2 uhf antennas, 1 800mhz antenna, 1 vhf and possibly a lowband antenna. Should these be certain distances from eachothee? This is on a dodge charger

The further apart the antennas are, the greater your chances are of not blowing the front end of the receiver from you other transmitters.

I use to run a 100 watt GE Delta SX on VHF and UHF. Managed to blow the front end on both several times until I installed some hot carrier diodes back to back on the gate of the front end FET used as a preamp. Don't forget to add a low value resistor in there also to keep from shorting the bias. I always tried to get on the coil side of the coupling cap so it would not effect the bias. Never lost a front end after that.

Jim

[SoCalRescue]

Thanks for the advice. The vhf antenna is only maybe a foot from the uhf now but I'll change that immediately. Gonna have some holes drilled on the roof and leave the vhf on the trunk. Any advice on the astro spectra Mic extension cable dilemma?

[Will]

Remember the mobile antenna rule: At least 1/4 wave from any edge.

The antenna has two parts, the antenna element or whip AND the ground plane. You need a 38 inch diameter for a VHF antenna just for the 'other half of the antenna', the ground or counterpoise.

[SoCalRescue]

Gotcha. I have some re-arranging to do now! Now does anyone have a solution for my spectra mic problem?!

[Will]

The Spectra Mic's have a tinsel like cord that does not take well to soldering. One way is some female DB connector pins that slip over the male pins on the control head, some silicone to hold them in. A four conductor shielded cable to a RJ jack. Then a good old GM300 mic plugged into the RJ 45 jack.

Also look an the VIP connector housing and it's pins as the connection to the 9000 head mic pins.

Some have used very fine copper wire to parallel the tinsel mic cord lead and a wire, wrapping the two together. Then soldering but not enough to burn up the tinsel wire.

Take a bad A5 or A7 control head and carefully unsolder the mic jack male pins and header from the circuit board. Wire in as above using a Spectra mic.

[Jim202]

Hey all.

1) is there a cable that will extend the microphone to the W9 control head and if so is there a part number/ someplace I can buy this? I mounted my w9 up where the sunglass fold down container normally goes abd I don't want the Mic hanging down. Id like the Mic down on the console where it normally goes but need an extension from the back of the W9 to the console.

If you really get desperate, you could take a bum head, cut out the mic connector and run some wires from it to the accessory connector on the radio. You didn't say which flavor radio it was, low or high power, dash or trunk mount. There is a chance you will have to move some surface mount jumpers around to get external PTT and mic audio from the connector.

Jim

[SoCalRescue]

It's a W9 head high power trunk mount. I am not tech savvy enough to fabricate one how you are describing it can be done. Are there no existing extension cables? I may have to find someone to make it for me and pay them.

[SoCalRescue]

I have an astro spectra doing 100 Watts out on VHF on one side of the trunk now and the XTL 5000 doing UHF 45 Watts on the opposite side. They are more than 38 inches from eachother I'm sure. I don't get any desense on rx on the uhf when keying vhf? Does that means the placement is safe?

[SoCalRescue]

Here's a picture.



IMAG0383_1 by mes90265, on Flickr

[SoCalRescue]

Enlarge the photo to see the whole trunk.

[Will]

Not good, NO ground plane... Remember the mobile antenna rule: At least 1/4 wave from any edge.

The RF will sneak down between the trunk lid EDGE and the body.

"What's a possible solution?" Ground straps which can be wide braid or 10 ga stranded insulated wire not longer than 1/8 wave at at frequencies you are operating at. Thee need to as short as possible. At each trunk lid hinge and at least one in the middle, two is better.. You are trying to bond the edge of the trunk lid to the body adjacent to it.

[SoCalRescue]

Drilling on this vehicle isn't an option for me? Trunk lid has worked fine for a year and a half - I was unaware of this issue... What's a possible solution?