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Sprite on 20M and Hum

Chuck Carpenter #53 Curt, I don't have a Sprite on hand just now but will soon.? I do have an original Pixie and I'll see how that behaves with my LM-317 most used supply and other rig power supplies; an old Kenwood analog and an Alinco switcher. I'm thinking that it might be ground loops or something like that.? As you know, it's a different problem than inadequate power supply filtering. Chuck, W5USJ (ex K2OFN) ARCI 5422, SKCC 19956 EM22cv, Rains Co., Texas -- Chuck, W5USJ
Chuck Carpenter #54 Just as a base-line sort of check, Hooked up the original Pixie, 7.122 MHz crystal, earbuds, 50 Ohm load, O'scope across earbuds, Butternut and long wire antennas. LM-317 adjustable bench supply, Alinco adjustable switcher,? 12.2 Vdc battery (3-cell Ii-ion).? Both adjustables have about 10mV no load ripple/noise. No noticeable 60/120 ac. I hear a low level ac hum from both supplies and the battery with no antenna connected.? It may be from the LM-386 audio amp.? Just touching the case on the chip makes a big difference. With Butternut connected, significant increase in noise and heard contesters in the background. Adjusting voltage with either supply, there was a definite null in noise between 11 and 12 V. The longwire, actually FS meter antenna, no radial, very intense noise level.? No help connecting to rig grounds. Sprite should be here later this week.? Anything else that would be helpful, informative...?? Chuck, W5USJ (ex K2OFN) ARCI 5422, SKCC 19956 EM22cv, Rains Co., Texas -- Chuck, W5USJ
Curt All Messages By This Member #55 开云体育 The shack supply I used was an MFJ-4125 switcher.? I will try the SEC1235M and see how that sounds.? As mentioned, all of my Pixies ( none are “original”), sound the same.? I will run some more experiments today. ? Curt ? Sent from for Windows 10 ? toggle quoted message Show quoted text From: Chuck Carpenter Sent: Monday, June 1, 2020 4:58 AM To: [email protected] Subject: Re: [QRpmeKits] Sprite on 20M and Hum ? Just as a base-line sort of check, Hooked up the original Pixie, 7.122 MHz crystal, earbuds, 50 Ohm load, O'scope across earbuds, Butternut and long wire antennas. LM-317 adjustable bench supply, Alinco adjustable switcher,? 12.2 Vdc battery (3-cell Ii-ion).? Both adjustables have about 10mV no load ripple/noise. No noticeable 60/120 ac. I hear a low level ac hum from both supplies and the battery with no antenna connected.? It may be from the LM-386 audio amp.? Just touching the case on the chip makes a big difference. With Butternut connected, significant increase in noise and heard contesters in the background. Adjusting voltage with either supply, there was a definite null in noise between 11 and 12 V. The longwire, actually FS meter antenna, no radial, very intense noise level.? No help connecting to rig grounds. Sprite should be here later this week.? Anything else that would be helpful, informative...?? ? Chuck, W5USJ (ex K2OFN) ARCI 5422, SKCC 19956 EM22cv, Rains Co., Texas -- Chuck, W5USJ ? C09DFF5A4DD747A39E21117C94EB830F.png
Curt All Messages By This Member #56 Edited Ok, must be peculiar to the MFJ-4125.? I hooked up the SEC1235M and no hum heard.? No issues using the MFJ on any of other radios except for Pixie variants.? Sorry for the detour. Both supplies cause BCI from strong local AM station on 700 kHz.? Battery supplies don't cause BCI ? Curt ? Sent from for Windows 10 ? toggle quoted message Show quoted text From: Curt Sent: Monday, June 1, 2020 6:54 AM To: [email protected] Subject: RE: [QRpmeKits] Sprite on 20M and Hum ? The shack supply I used was an MFJ-4125 switcher.? I will try the SEC1235M and see how that sounds.? As mentioned, all of my Pixies ( none are “original”), sound the same.? I will run some more experiments today. ? Curt ? Sent from for Windows 10 ? From: Chuck Carpenter Sent: Monday, June 1, 2020 4:58 AM To: [email protected] Subject: Re: [QRpmeKits] Sprite on 20M and Hum ? Just as a base-line sort of check, Hooked up the original Pixie, 7.122 MHz crystal, earbuds, 50 Ohm load, O'scope across earbuds, Butternut and long wire antennas. LM-317 adjustable bench supply, Alinco adjustable switcher,? 12.2 Vdc battery (3-cell Ii-ion).? Both adjustables have about 10mV no load ripple/noise. No noticeable 60/120 ac. I hear a low level ac hum from both supplies and the battery with no antenna connected.? It may be from the LM-386 audio amp.? Just touching the case on the chip makes a big difference. With Butternut connected, significant increase in noise and heard contesters in the background. Adjusting voltage with either supply, there was a definite null in noise between 11 and 12 V. The longwire, actually FS meter antenna, no radial, very intense noise level.? No help connecting to rig grounds. Sprite should be here later this week.? Anything else that would be helpful, informative...?? ? Chuck, W5USJ (ex K2OFN) ARCI 5422, SKCC 19956 EM22cv, Rains Co., Texas -- Chuck, W5USJ ? ? ? C09DFF5A4DD747A39E21117C94EB830F.png

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