Army, et al: At this point, I'm suspecting RF as well. But why with so little power? In the past, with a traditional rig I haven't seen a problem like this, but with the Flex 5000A, with as little as 1W out, I'm having problems.
To answer your question, the reason both temporary antennas are 30M antennas so I can tune them for 6-40m and run low power SSB. The MMD antenna is supposed to have a Current-Mode Discriminator which, among other things, is supposed to prevent RF running back down the feedline. The dipole is a textbook dipole fed with coax. If I transmit into a dummy load (a giant 50ohm resistor I bought at a ham fest). I can run full power with no problems whatsoever. No buzzing, no feedback, no distortion. Audio sounds fine in another receiver. Also, I don't have a traditional RF ground yet and the radio is on the 4th story of a building. I do own an artificial ground tuner, which I haven't tried yet at this QTH. As I've said, I'm setting up this QTH new, so I'm trying to minimize what's necessary, rather than hooking everything up at once. By spring time, I'll hook up a RF suppressor Ground system (like the one in the grounding article in the Flex Knowledge center). I'm just trying to operate on a modest setup for the winter. Any ideas on how I can solve this problem and operate under these constraints? *B KK2QQ -----Original Message----- From: Army Curtis - AE5P [mailto:a...@suddenlink.net] Sent: Sunday, December 05, 2010 1:48 PM To: 'Bradley Feldman' Subject: RE: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues Hi Bradley, I've been following your adventures this morning with your new Flex. Everything you have said so far points to RF getting back into the radio/computer/speakers. Your first post seemed to indicate you had transmit audio feedback from either radio speakers that were reproducing transmit audio because the Monitor button was activated in PSDR, or you had a second receiver in the shack to listen to your transmit audio. If you want to listen to your transmit audio, you MUST prevent the audio from getting back into the microphone and creating a big feedback loop. Since the first post, your symptoms now sound like a classic case of RF feedback (different from audio feedback). You speak of a 30M antenna, first an end fed model and then a dipole fed with coax. I'm a little confused here. 30 meters does not permit SSB operation; only CW or digital. Am I understanding you correctly? Also, a dipole is inherently a balanced antenna, which you are feeding with coax, an unbalanced feed line. Very common practice I grant you, but one that is also very prone to bringing RF back into the shack. Do you have a dummy load? That would be a much better test if you have one. Hook up the dummy load in place of the antenna, and try things again. Remember to use headphones to listen to your transmit audio so you don't have audio feedback, and check things out at several different drive (output power) levels. Watch your mike levels as you transmit, adjusting mike gain so the mike indication on the meter does not go over 0 dB, even on voice peaks. HF RF can cause the same type of sounds from powered speakers that VHF FM can, so I don't think you are having an issue with the V/U modules being keyed by mistake. I also have a 5000 with all the goodies, and totally love it. I hope some of these suggestions will help you get the issues worked out successfully. Let me know please of any of these ideas work for you. 73, Army - AE5P -----Original Message----- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Bradley Feldman Sent: Sunday, December 05, 2010 12:26 PM To: 'Bret Mills'; flexradio@flex-radio.biz Subject: Re: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues One more thing. I do also hear buzzing out of the amplified speaker for the radio (separate AC sound amp with ground loop isolator, shielded cables) and through the computer's speakers (also ground loop isolated). In the past I've heard this type of buzzing with FM transmit, but never ever with HF transmit. Could the VHF/UHF board be keying up with the HF? *B KK2QQ -----Original Message----- From: Bret Mills [mailto:bmil...@ecso.com] Sent: Sunday, December 05, 2010 12:40 PM To: 'Bradley Feldman'; flexradio@flex-radio.biz Subject: RE: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues Yep it sounds like it is wired correctly, It must be RF getting into the Radio some how, Have you tried transmitting into a dummy load to see if there is still distortion?? RF gets into the MIC TX circuit quite easily if you are in the "near field" of your Antenna system and you may need to add some snap on MIX 31 ferrite beads as I have done here that were required when I run my AMP to full power in my situation, these are just like the ones on the Fire wire cable. Just a few suggestions that I have ran into in my 2.5 years of running 2 FLEX 5K's and a Flex 3K here. Hope this helps Bret WX7Y -----Original Message----- From: Bradley Feldman [mailto:brad...@bradleyloritheo.com] Sent: Sunday, December 05, 2010 9:54 AM To: 'Bret Mills'; flexradio@flex-radio.biz Subject: RE: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues The PTT is connected properly to pins 5+6. Mic positive (XLR pin 2) is connected to flex pin 8. Mic negative (XLR pin 3) and Mic Shield (XLR pin 1) are tied together at the flex side and go to flex pin 7. The barrel on the flex side isn't connected to anything. Does that sound correct? *B KK2QQ -----Original Message----- From: Bret Mills [mailto:bmil...@ecso.com] Sent: Sunday, December 05, 2010 11:45 AM To: 'Bradley Feldman'; flexradio@flex-radio.biz Subject: RE: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues Page 5 of the FLEX 5K's owners manual show the proper connections for the FLEX-5000 MIC connector, I quote "Pin 5 is Chassis Ground, Pin 6 is PTT, Pin 7 MIC (-) Pin 8 MIC (+)". Measure from the MIC itself and make sure they have the correct one connected. 73's Bret WX7Y -----Original Message----- From: Bradley Feldman [mailto:brad...@bradleyloritheo.com] Sent: Sunday, December 05, 2010 9:25 AM To: 'Bret Mills'; flexradio@flex-radio.biz Subject: RE: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues On the Heil cable I'm using, the PTT is on pins 5+6. The mic is on pins 7+8. Should the barrel of the connector be connect to anything? *B KK2QQ -----Original Message----- From: Bret Mills [mailto:bmil...@ecso.com] Sent: Sunday, December 05, 2010 10:57 AM To: 'Bradley Feldman' Subject: RE: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues Check the HEIL MIC adapter and MAKE sure that the MIC ground goes to the radio MIC Ground and the PTT Ground goes to PTT Ground on the radio. On a LOT of the HEIL adapters they wired the ground pins backwards and this may be the cause of your problems, on Yaesu radios this didn't make much difference but on the FLEX it makes ALL the difference in the world. Hope this helps and 73's and Happy Holidays Bret WX7Y -----Original Message----- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Bradley Feldman Sent: Sunday, December 05, 2010 8:37 AM To: flexradio@flex-radio.biz Subject: [Flexradio] New 5000A User - TX Audio (severe distortion) Issues I'm new to flex, sdr and this list. I have a brand new 5000A, fully loaded (including the VHF/UHF board). Station is completely new -- new QTH, new Mic (PR 781), new temporary antenna (Miracle MMD 30m). I've worked through issues on installation and receive and seem to have those licked including using VAC with digital modes. Now I'm trying to get TX working right for working QRP until spring comes and I can set up my Steppir Bigir that's sitting here in a box. I've been a ham since 1990, but have largely been on my own with regard to setting up and solving shack problems-- I don't belong to any clubs at the moment, so I appreciate any help I can get from this list with the issue I describe below -- which may not be a "flex issue" but perhaps an ordinary ham setup issue. I don't know. Here's the issue: When keying up and testing my mic in phone mode (I don't have a key set up), once there is enough audio level to drive some rf output power, I start to hear distortion in the audio-- it kind of sounds like the sound of a helicopter with echo and reverb that continues until I unkey. I've done Google searches, flex KB searches, forum searches and read the flex troubleshooting guide to try and find a solution. Based on that information, I've tried the following: I've grounded the radio to the PC with ground strap. I installed RS ground loop isolators on all audio connections to/from the radio and PC. I put extra ferrites on the PC side of the stock flex firewire cable. The issue remains. Any ideas of what to do next or what additional info is necessary to help me? *Bradley KK2QQ _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
