Mitrek Rx side connector details

by AK2O

 


Introduction

If you choose not to cut a flat surface of the radio for proper mounting of the Rx connector you'll need to modify it another way. Dremmel out the hole to fit a BNC connector. This takes a lot of practice and an hour of precision grinding. If you use a bulkhead type you need to grind back inside to provide a surface for the (modified) nut to tighten down the (modified) bulk-head BNC double female connector. Another option is to use a BNC chassis type connector, with the 4 mounting holes.

Otherwise if you do cut the front flat a chassis BNC will fit very nicely, with a little "adjustments". That's the round type of connector (no flag/holes). Chosen was Mouser part #: 523-31-318-RFX , or Jameco part #: 355223. You will need to grind the lower half of the hex surface to fit in the round inset of the radio's chassis (inside side). Also grind down the "lip" around the edge (for the rubber seal not used), so it fits better and extends out to give you a few more threads exposed for the nut and lock washer.



 

 

 

 

 

 

 

 

 

 

 

The receiver's coax has a twist; There's an outer shield layer on the Rx side. So you'll be dealing with smaller center conductors and pins for the connectors. The OEM Rx cable was stripped back to solder the pin of the BNC connector. It takes some getting used to the tiny cable center.



 

 

 

 

 

 

 

 

 

 

 

 

Since the Rx side is double shielded a little preparation is needed to solder both of them to the connector's outside.



 

 

 

 

 

 

 

 

 

By routing the cables this way you can still use the stock PL deck. For linking applications this is not a factor, since all the tone decoding is performed at the far end, while the links are carrier squelch. Remember that the Rx cable is opposite of what you would think of, having the double shielding. (one would expect the Tx side to have it).



 

 

 

 

 

 

 

A nice way to route it, is make a sharp turn halfway down the preselector. Make a 4mm notch (W x D) in the first casting divider so that clip can be soldered to the outer shield at that point. From the inside surface of the "left" side of the unit 87mm on center of this notch. The bottom of the notch can be rounded for the coax.

 

 



 

 

 

 

 

 

 

 

 

Here's latter pictures of this idea: Make a notch in the chassis large enough for the Rx coax run. The location of the notch was (slightly) changed to this in 2009 to permit a cor board to be mounted next to it.



 

 

 

 

 

 

 

 

 

The ground clip is optional.



 

 

 

 

 

 

 

 

 

Prep the end of the cable for the Rx connector.



 

 

 

 

 

 

 

 

 

 

Both braids soldered onto the connector's housing. Only moderate torque is needed on the nut for mounting.



 

 

 

 

 

 

 

 

 

 



This is the end of the connector details. Refer to the first document for the radio project.

Copy write: AK2O 2007, 08, 09


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