[TenTec] Orion and MIKEs

[JULIUS JONES]

I recently sold an 8 Band EQ to a customer for use with the ORION. Having sold hundreds of EQ's for use with other TenTec radios we shipped the customer one of our TenTec 4 to 8 pin mic adapters along with a cable to go between the EQ and the Orion. This was the first ORION, that I knew about, that the 8 Band  EQ had been connected to. The customer was using a Studio 1 Heil Mic. To my surprise the hardware shipped would not key his radio. The customer was shipped another EQ and cables. This did not work also. I downloaded the Orion operating manual and looked at it.  Before the Orion prior Ten Tec radio's had 4 pins mic configurations where the audio ground and the PTT grounds were shared on pin 2 of the 4 pin mic connector, + audio was connected to pin 1, PTT was connected on pin 3 and +9 volts DC was connected on pin 4.  Figure 2-4 on page 10, of the Orion manual ,is not the configuration of the 4 pin male connector of the ORION but a configuration of a mic output without a
 connecting cable.  Figure  2-5 , I believe  was meant to represent the cable that connects between the mic in figure 2-4 and the Orion input shown in figure 2-3 shown on page 9 of the manual.  The key thing to understand is that the ground return for the PTT instead of being shared with pin 2 is connected to the shell of the connector. Using the shell connection of the 4 pin mic connector  makes it possible to provide a 5-th signal for mic control (+ Audio, Audio gnd, PTT, + 9 VDC and PTT gnd)  We experienced RFI in the audio when using a linear amplifier when the  PTT and Audio shared a ground. When the PTT and audio grounds were isolated (the  EQ utilizes an audio transformer)  the audio was clean. I have not talked to Ten Tec but I would have to believe that having to use the  shell of the connector  was probably something that they found was needed after the radio was designed. Those of you that have mic's that share PTT grounds and audio grounds beware. You will likely have an
 RFI problem when using a linear. I hope this explains what is going on. I hope my explaination helps.  Thanks to N4VB for making me aware of postings on this subject   Julius (W2IHY)