Everyone, I think the measurements and discussion by Leif Asbrink, http://www.sm5bsz.com/dynrange/dubus313.pdf, is of interest to anyone in the amateur radio hobby. It is of particular interest to VHF and UHF operators where the noise floor to maximum signal amplitude may be greater than the 77 dB signal difference between the carrier and sideband noise of a Flex5000 at +/- 350 kHz from the carrier frequency.
For HF operation where atmospheric noise is predominant the sideband noise is not an issue. For example, one is operating at 3.900 MHz and a very strong Flex5000 carrier is detected at S9 + 20 dBm, which is -73 + 20 dBm = -50 dBm. Based on Leif's measurements, peaks in sideband noise of -77 dBc will occur at 3.900 +/- 0.350 MHz, which are 3.550 and 4.250 MHz. The amplitude of these noise peaks will be S9 - 77 dBm = -50 dBm - 77 dB = -127 dBm. On 3.550 MHz, the CW portion of the 80 meter band, at a very quiet location, the typical noise floor will be S5, which is 4 S units or 24 dBm below S9. Therefore, the noise floor is at S9 - 4 S units = -73 dBm - 24 dBm = -97 dBm. So, the sideband noise peak is -127 dBm - (-97 dBm), which is -30 dBm or 30 dBm below the noise floor. Clearly, for HF operation the Flex5000 sideband noise is not an issue. Some questions for the Flex Company. 1. Has the Flex Company made measurements of the sideband noise amplitude? 2. How do these measurements compare to those reported by Leif? 3. Is the sideband noise amplitude still -77 dBc for current Flex5000s? 4. Is the sideband noise amplitude still -77 dBc for the Flex6000 series? By the way, I am a happy user of a Flex5000 on the HF bands and am trying to keep some perspective about the issues raised by Leif. I do not operate on VHF and UHF so I cannot comment about those frequencies. I think the above analysis is correct and hope others will add their ideas. Paul Jursinic K9IRO -----Original Message----- From: FlexRadio [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Jim Jannuzzo Sent: Thursday, October 17, 2013 5:51 PM To: draxfel...@gmail.com; Mike Cc: flexradio@flex-radio.biz Subject: Re: [Flexradio] FlexRadio Digest, Vol 102, Issue 15 I wonder what happens if he tests a current production version of the 5000? He trashed the transmitter based on 2008 test data, and things have changed a lot since then. Jim KJ2P > From: draxfel...@gmail.com > Date: Thu, 17 Oct 2013 15:30:10 -0400 > To: mi...@m0aws.co.uk > CC: flexradio@flex-radio.biz > Subject: Re: [Flexradio] FlexRadio Digest, Vol 102, Issue 15 > > I wonder what happens if he pulls in the transmit filter in PowerSDR what > effect that has. > > > On Oct 17, 2013, at 1:36 PM, Mike <mi...@m0aws.co.uk> wrote: > > > > Hi, > > > > That's a real interesting read, I wonder if anyone at FlexRadio cares to > > comment? > > I'd like to know how badly my F3K TX is performing too! > > > > Mike. > > > >> On 17/10/13 18:00, flexradio-requ...@flex-radio.biz wrote: > >> Message: 4 > >> Date: Wed, 16 Oct 2013 14:59:37 -0400 > >> From: "Gedas" <w8...@mchsi.com> > >> To: <flexradio@flex-radio.biz> > >> Subject: [Flexradio] Noise Sidebands, Article by SM5BSZ > >> Message-ID: <399ADD464530473F88C1CBF0659768F5@biggy> > >> Content-Type: text/plain; charset="utf-8" > >> > >> I came across this interesting article by SM5BSZ who discusses some > >> possible transmitter issues with many radios, including the Flex. It has > >> me a bit concerned. I am wondering if anyone has seen similar data for > >> the Flex 5000? The article may be found here: > >> > >> http://www.sm5bsz.com/dynrange/dubus313.pdf > >> > >> Gedas, W8BYA > >> Gallery at http://w8bya.com > >> Light travels faster than sound.... > >> This is why some people appear bright until you hear them speak. > > > > > > _______________________________________________ > > 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/ _______________________________________________ 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/
