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Sunday, 6 September 2015

Codan 9780 HF Transceiver

I recently acquired a used Codan 9780 HF transceiver. This is a commercial HF SSB transceiver that provides 15 user programmable channels in the 2.25 to 30MHz range.  Power output is 125w of USB or LSB.

Codan 9780


The radio was purchased without a microphone and I thought it would be straightforward to find a suitable replacement microphone, however a search online only found original replacement microphones at AU$ 389  - way more than I was prepared to pay.

I found the schematic of the Codan keypad microphone on the aboutcodan.blogspot.com blog - this is a very useful blog with lots of information on Codan 9xxx series radios , including how to enable programming of channels from the control panel.
The microphone schematic is here .
The schematic indicated that it would be possible to connect a normal dynamic microphone to the radio , leaving out the custom keypad controller.  I had an old Pama dynamic CB microphone that looked suitable , so the next problem was to find a suitable microphone plug. Unfortunately the 9780 has a very custom 7 pin connector - I wasn't able to find a suitable connector at a reasonable price , but I found an eBay seller in Australia that had a replacement Codan microphone cable and plug for AU$ 65.  This was ordered and it arrived about 2 weeks later .  Mic plug shown below.

9780 mic plug

I found the pinout of the MIC socket in the Codan 9360 reference manual available here .
Note - this pinout is viewed from the perspective of the radio front panel, not from the microphone plug.

Microphone socket pinout

It was necessary to link pins 1 and 7 together in order to route the received audio to the front panel speaker.  This is illustrated in the microphone schematic .

On connecting the microphone I found I was still not getting any audio out of the front panel speaker , so I plugged in an external speaker into the LS jack on the back .  This worked.

On removing the front panel and testing the speaker I found that it was open circuit .  The speaker is a 66mm diameter mylar speaker  - maplin had a suitable replacement ( code VC86T)  . 

front panel speaker
Once this was replaced I tried the radio out and made a number of contacts on 80m , 60m and 40m and received good audio reports.  

Having only 15 channels is a limitation, but I plan to use it mainly on 60m where we only have access to 5 spot frequencies in Ireland.








2 comments:

  1. Could you tell me how to set the audio gain. My microphone is far too low only making 10 watts output with 100 watts roger beep. Is Mic gain a software setting ?

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  2. I don’t think there is a software mic gain setting. According to the manual there is a mic compressor amplifier that produces a consistent output for a wide variation of input levels.

    “The microphone audio at the output of IC204/A is applied to the input of a microphone compressor amplifier consisting of IC204/B, IC205/A and B, V202 and associated components. This provides a constant output for a large variation in speech levels applied to the input (≈30 dB range).
    When there is no speech present, the amplifier IC204/B is set to the maximum gain. “



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