Cobra 29GTL/LTD ?

[Techno1]

On the Cobra 29 ltd/gtl and the Dwight D and cobra 1000.

Is there a location on the pc board to monitor the frequency with a freq counter.

I know on the Cobra 142/Madisons/Washington and radios that use the MB8719/8735 pll TP 1 which is a resistor on 1 side is a good place to monitor the frequency. Is there a point on the AM radios mentioned above to do this?

thanks

 

[nomadradio]

There is, but you'll have to choose whether you want to display the receive or the transmit frequency. The radio's PLL jumps down 455 kHz when you key the mike. The fleabay PLJ6-LED counter board has an offset feature you can set for most any radio, but the AM radios you mention all share this " transmit jump" design.

On a Cobra 29LTD I would use the output side of L18. One side has two pins, the other side has three. One end of the 3-pin side is ground, you want the opposite "hot" side of L18. Use a 100 ohm or higher resistor between L18 and the counter input. Most counters have a blocking capacitor on their input, so a resistor alone should serve to keep the counter input from loading down the radio's PLL source. That would reduce receiver sensitivity and transmit power.

In a Cobra 1000 or 89GTL it's labeled "TP2", on the output of L18.

Sure wish somebody sold a version of the PLJ6 with multiple offsets selectable by input ports like the Galaxy built-in frequency displays. Would solve the problem for these AM-only radios.

73

 

[Techno1]

I have 2 of these on the way and was hoping to install 1 in a cobra 29ltd that has 80 extra channels.
So it will read receive and what will happen on transmit nothing will show?

Here is the pdf for the OLED and I dont see any offset function

thanks

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[Techno1]

if L18 is for receive what point will be for transmit.

What about a small relay that the input to the relay common is the counter.
And 1 receive point goes to 1 pole and the transmit the other pole.
so when u key it will show Transmit and no key it will show receive.

You can use pin 3 as the key for the relay.
I have these real small mini relays that would work perfect if it will work.

i guess i will have to try when the OLED counters arrive.

Someone mounted 1 in this SSB radio

 

[Techno1]

So I was probing around a Cobra 29LTD and I see L18 is transmit no receive and I did not find a location to monitor receive so I guess adding 1 of these to a Cobra 29/25 and other AM radios is not a good thing at the moment as you will only be able to get transmit to activate the OLED counter.