[NHRC-user] NHRC-Micro Problems

[Jeff Otterson]

If you are going to couple speaker audio from your handheld, I recommend a 
transformer for isolation. Some handhelds cannot tolerate either leg of the 
speaker output getting grounded.

The audio input of the NHRC-Micro has a 10 K pot to ground.  If you are 
relying on a DC bias on the RX audio lead to indicate COR, then you will 
want to AC couple the audio into the controller with a capacitor, perhaps 1 
to 10 uF.


Jeff

At 09:14 PM 2/6/2010, you wrote:

>I just bought a used NHRC-Micro from a guy on Ebay a few days ago. He still

>has several of them for sale at $80 a piece. Money is tight so that's the

>route I took as opposed to spending another 40 bucks to buy new. Might have

>to buy another one from him if I can't fix this one. The controller was

>working fine here at the house. I had just got it programmed and working

>well as a temporary cross band repeater between UHF and VHF handhelds when

>something happened last night. The RX audio voltage started going to ground

>on the controller. Not sure what I did (I might have toasted something by

>connecting a speaker to the RX audio high and low on the terminal strip

>without thinking) but this is how I had it set up:

>

>All connections were made on a terminal strip. I was using a second

>controller in the configuration to use a +COS because the harness that came

>with the Micro did not have a +COS lead in the connector but only a -COS

>lead. So I provided the -COS source for the Micro with the extra relay on

>the second controller. The +COS source for the second controller was about

>3.5V unsquelched from the audio high lead from the handheld used as the RX.

>The PTT from the handheld used as the TX had 5V and was connected to PTT on

>the Micro and to the wiper on the relay. TX and RX audio was connected to

>the Micro. Everything was fine with this setup for awhile. When the squelch

>opened on RX the +COS saw 3.5V and keyed controller 2. The PTT on controller

>2 went to ground and the N.C. lead on the relay opened and activated

>the -COS for the Micro. The PTT on the Micro went to ground and keyed the

>TXer. The courtesy tones and CW sounded good. It programmed very well with

>the serial cable and your software. I don't know how the audio sounded thru

>this setup as I had no way of TXing and hearing it at the same time. As of

>today I do have a way but now the Micro has a problem with this RX audio

>going to ground. When the squelch opens, the RX audio high from the RXer

>quickly loses voltage going from 3.5V to almost 0 in about 3 seconds almost

>like a quick discharge of a capacitor. When ground is removed from the Micro

>the RX audio voltage remains steady at 3.5V when unsquelched. So sounds like

>one of those microscopic components went south on me.

>

>I would really appreciate any clues on this. We are planning a trip to the

>area of my repeater about 200 miles away for next weekend and I really need

>a controller to take with me to install. These components are very small on

>the Micro so looks like a repair job (by me) is not an option. Looks like I

>may be out 80 bucks and a postponement of the much needed controller

>install. I will hold out some hope that maybe someone on this list might be

>able to help me.

>

>Thanks for your time.

>

>Roy

>N7DWC

>

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