bias tee circuits and components for 2.4 GHz downconverter
I have a Pacific Monolithics surplus MMDS downconverter here that I would like to get up and running on S-band. It has an 122 MHz IF and I want to whip up a bias -tee to power it. I've looked at the circuits in the Satellite Experimeters handbook and my problem is finding an rf choke of the right value that is readily available in my area. Shouldn't I be able to just wind something with an air core out of magnet wire or something similar that will do the trick? According to the circuit I have I'd need about a 1.5 uh choke for 146 Mhz and it isn't critical so that's probably close enough for my downconverters IF frequency. I hate to spend shipping charges to get one little choke or ferrite core for winding a choke on here. Most places have a minimum order and I don't need anything else at this time. I'd also welcome links to any other circuits that might be out there. Thanks, Michael, W4HIJ
Did you try a local TV repair shop? Many times, I have been able to buy small parts like chokes from them, when Radio Shack didn't carry them...
----- Original Message ----- From: "Michael Tondee" mat_62@netcommander.com To: "amsat-bb" amsat-bb@amsat.org Sent: Sunday, May 11, 2008 12:01 PM Subject: [amsat-bb] bias tee circuits and components for 2.4 GHzdownconverter
I have a Pacific Monolithics surplus MMDS downconverter here that I would like to get up and running on S-band. It has an 122 MHz IF and I want to whip up a bias -tee to power it. I've looked at the circuits in the Satellite Experimeters handbook and my problem is finding an rf choke of the right value that is readily available in my area. Shouldn't I be able to just wind something with an air core out of magnet wire or something similar that will do the trick? According to the circuit I have I'd need about a 1.5 uh choke for 146 Mhz and it isn't critical so that's probably close enough for my downconverters IF frequency. I hate to spend shipping charges to get one little choke or ferrite core for winding a choke on here. Most places have a minimum order and I don't need anything else at this time. I'd also welcome links to any other circuits that might be out there. Thanks, Michael, W4HIJ
Michael, Anything over 0.5 uH should work well, suggest you use 1.5 feet of # 28 to #36 enameled wire from an old transformer on a 1/2 watt carbon resistor 10K or larger. Put some of your Wife's fingernail polish on it to hold the wire in place. A small flame will burn the enamel off the ends of the wire and clean the soot of with a pen knife or sandpaper, wrap and solder the ends of the wire to the resistor leads. Use a quality small ceramic capacitor 220 pF to 1000 pf as a blocking capacitor, keep leads very short. 73, Art, KC6UQH
----- Original Message ----- From: "Michael Tondee" mat_62@netcommander.com To: "amsat-bb" amsat-bb@amsat.org Sent: Sunday, May 11, 2008 10:01 AM Subject: [amsat-bb] bias tee circuits and components for 2.4 GHzdownconverter
I have a Pacific Monolithics surplus MMDS downconverter here that I would like to get up and running on S-band. It has an 122 MHz IF and I want to whip up a bias -tee to power it. I've looked at the circuits in the Satellite Experimeters handbook and my problem is finding an rf choke of the right value that is readily available in my area. Shouldn't I be able to just wind something with an air core out of magnet wire or something similar that will do the trick? According to the circuit I have I'd need about a 1.5 uh choke for 146 Mhz and it isn't critical so that's probably close enough for my downconverters IF frequency. I hate to spend shipping charges to get one little choke or ferrite core for winding a choke on here. Most places have a minimum order and I don't need anything else at this time. I'd also welcome links to any other circuits that might be out there. Thanks, Michael, W4HIJ _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (3)
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George Henry -
kc6uqh -
Michael Tondee