Converting a Gentner Microtel for cell phone use

[radiorob2.0]

The Gentner Microtel is a wonderful piece of equipment and I want to interface it with a cell phone. I’ve began to search the net for an adapter but no luck so far. What I’m looking for is a converter to change a handset cord to a cell phone hands free adapter. Do you have any suggestions?

 

[NE Miss Radio]

Can you rig your hands free to the aux input? I had a Conex Celljack II and made a cable to take my cell phone headset jack to the aux input on the Celljack. Had to add a headphone amp for $50 but it was worth it.

 

[trm420]

Conex sells it's flipjack that interfaces into the sub mini jack on the cell phone, which is ok unless you have a motorola that uses a mini-usb jack.

 

[spinjector]

The Gentner Microtel is a wonderful piece of equipment and I want to interface it with a cell phone. I’ve began to search the net for an adapter but no luck so far. What I’m looking for is a converter to change a handset cord to a cell phone hands free adapter. Do you have any suggestions?

Yes, I use those as well for IFB. I love the little buggers.

That should be quite an easy cable to make. Just solder a cord with an RJ-22 handset plug on one end, and a 3/32" sub-mini stereo plug on the other end. I think the tip is the microphone and the ring is the earpiece. I'd have to meter them out to be sure.

Contact me directly if you like, and I can help you with it. Here is my email, but you will have to translate it into a real email address. I don't want spam robots to scan the site and get hold of it -----> mshea_AT_entercom_DOT_com.... ;D

I could even make one up and send it to you if you send me your snail-mail address.

Matthew Shea, Radio Engineer
Entercom Communications
WBEN, WTSS, WKSE, WWKB, WGR, WWWS, & WLKK
500 Corporate Parkway, Suite 200
Buffalo, New York, USA 14226

 

[sparks794]

Can you rig your hands free to the aux input? I had a Conex Celljack II and made a cable to take my cell phone headset jack to the aux input on the Celljack. Had to add a headphone amp for $50 but it was worth it.

I did something similar years ago with one of the older "bag" phones. I built an interface so we could connect our shure mixers to it - transformer isolated it and used it with the hands free function. Sounded great for what it was.

 

[Field_strength]

That should be quite an easy cable to make. Just solder a cord with an RJ-22 handset plug on one end, and a 3/32" sub-mini stereo plug on the other end. I think the tip is the microphone and the ring is the earpiece. I'd have to meter them out to be sure.

I tried to make such a cable for a Palm Treo phone with no luck. Somehow, the phone "knows" the difference between a pair of stereo headphones and a headset. When you plug a set of headphones in to the aux plug, you get stereo audio. But when you connect a headset w/ mic, it knows to use one channel as an input for the mic and the other as a earpeice output. The cable I made doesn't switch the phone from stereo out mode to in/out mode like I need it to. Has anyone overcome this? How can you "trick" a Palm Treo so that you can use the aux plug for line or mic level in/out?

 

[spinjector]

Hmmm...interesting. It just so happens I am a Treo fanatic and I have a 700w. I would think it senses the impedance and/or resistance of the earphone and/or microphone, and switches its interface mode accordingly. I know that "walkman style" headphones are high-impedance; in the range of 12-16 ohms. As for the small condenser or electret microphones that are used in headsets, I have no idea what impedance they are. Furthermore, I don't know which of the two, if not both, the Treo watches the impedance of.

If there was a way to find out the impedance of the Microtel in/out, there might be a way to make it appear like a headset to the Treo....maybe fiddle with some capacitors and/or resistors in the in/out circuits.