It is the way the radio is designed and yes, being a direct conversion radio has a lot to do with it too. Those other radios are multiple conversion superhets.
Direct conversion receivers have high dynamic range, but are susceptible to images. -Tim -----Original Message----- From: flexradio-boun...@flex-radio.biz [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Dr. J Roth Sent: Sunday, March 14, 2010 10:08 AM Cc: Flex Radio Subject: Re: [Flexradio] Flex 5000a RX below 550 Khz Would someone educate me as to why my Radio Shack DX-394 & Icom IC746PRO does such a good job of RX from 1 MHz down to 100Hz without images and no external filters? Is it only due to the conversion configuration? Joe > From: telli...@itsco.com > To: ka9...@hotmail.com; gerf...@mesanetworks.net > Date: Sun, 14 Mar 2010 09:50:45 -0400 > CC: flexradio@flex-radio.biz > Subject: Re: [Flexradio] Flex 5000a RX below 550 Khz > > It is due to all the mixing products. The filters are necessary for > reception in that frequency range. > > > > -Tim > > -----Original Message----- > From: flexradio-boun...@flex-radio.biz > [mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Robert delaney > Sent: Sunday, March 14, 2010 1:00 AM > To: Jerry Sharp > Cc: FLEXRADIO > Subject: Re: [Flexradio] Flex 5000a RX below 550 Khz > > Jerry, Thank you for the information about the Flex 1000 and it's performance > when a filter is added. > I am a bit concerned though with the Flex 5000. When tuning this area of > spectrum you will see all of the broadcast images and then when you pass a > certain frequency the whole panadapter suddenly almost magically changes to a > new set of images. > I can not hear any beacons under the QRM at all just spike after spike of > AM stations that aren't really there. > > 73, Bob > KA9UVY > ----- Original Message ----- > From: "Jerry Sharp" <gerf...@mesanetworks.net> > To: "FlexRadio" <FlexRadio@flex-radio.biz> > Sent: Saturday, March 13, 2010 11:29 PM > Subject: Re: [Flexradio] Flex 5000a RX below 550 Khz > > > > Bob, like Dudley mentions, you'll need a low pass filter that cuts > > off at 400-500 KHz. In fact, I run two in series to keep all the > > broadcast junk out. > > > > Every radio I've even owned that tuned below 500 KHz worked the > > same...all kinds of BCB "junk" unless you add a filter, including my > > Drake R8, Drake TR7, and Yaesu FT-847. > > > > Right now I'm running a short 36" active antenna for LF into my > > SDR-1000 (with of course the low pass filters in line). From > > Colorado in the winter I have copied non-directional beacons from > > South and Central America, Greenland, and the South Pacific. I've > > also copied several 1 watt Lowfer experimental stations in the 170-190 KHz > > range from across the USA. > > > > The panadapter is ABSOLUTELY WONDERFUL for spotting extremely weak > > LF and VLF CW signals! And my SDR with low pass filters is by far > > the finest receiver I've ever owned for LF and VLF! > > > > 73, > > Jerry Sharp, KD0GS > > > > Dudley Hurry wrote: > >> Bob, > >> > >> You will need a low pass filter of the range you are planning to use. > >> Many have report good results with a 500 khz cutoff low pass or > >> you can build your own.. > >> 73, > >> Dudley > >> > >> WA5QPZ > >> > >> > >> > >> Robert delaney wrote: > >>> I seem to have nothing but images of the AM broadcast band on my > >>> 5000A when looking for non directional airport beacons between 150 > >>> and 500 Khz. > >>> Has anyone else noticed this image issue? I understand that the > >>> radios specs are for the ham band but I thought it would at least > >>> RX down there. > >>> > >>> Thanks, 73 > >>> Bob > >>> KA9UVY > >>> _______________________________________________ > >>> FlexRadio Systems Mailing List > >>> FlexRadio@flex-radio.biz > >>> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.b > >>> iz > >>> Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > >>> Knowledge Base: http://kc.flex-radio.com/ Homepage: > >>> http://www.flex-radio.com/ > >>> > >>> > >> > >> _______________________________________________ > >> FlexRadio Systems Mailing List > >> FlexRadio@flex-radio.biz > >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.bi > >> z > >> Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > >> Knowledge Base: http://kc.flex-radio.com/ Homepage: > >> http://www.flex-radio.com/ > >> > >> > >> ------------------------------------------------------------------- > >> ----- > >> > >> > >> No virus found in this incoming message. > >> Checked by AVG - www.avg.com Version: 8.5.436 / Virus Database: > >> 271.1.1/2745 - Release Date: 03/13/10 21:51:00 > >> > > > > > > _______________________________________________ > > 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.flex-radio.com/ Homepage: > > http://www.flex-radio.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.flex-radio.com/ Homepage: > http://www.flex-radio.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.flex-radio.com/ Homepage: > http://www.flex-radio.com/ _________________________________________________________________ Hotmail: Trusted email with Microsoft's powerful SPAM protection. http://clk.atdmt.com/GBL/go/210850552/direct/01/ _______________________________________________ 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.flex-radio.com/ Homepage: http://www.flex-radio.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.flex-radio.com/ Homepage: http://www.flex-radio.com/
