My e-mails don't make it through Yahoo groups for some reason.....let's see if this one works.
Some possibilities for you to consider.....I ran a quick and dirty model of a 40' random wire fed against the ground at one end and 10' off the ground at the far end and got nice low SWR points (ref to 50 ohms) at around 6.5 MHz, 18.5 MHz, and 30 MHz. I suspect this was NOT your situation however since my wire model was referenced against ground. What did you feed that 40' end fed wire against at the rig? The random wire needs to be fed or referenced against an RF return. Did you provide the radio with a RF ground connection to feed the wire against? If the rig is totally floating and battery operated (no external connections of any kind) then that wire will present a high-impedance with only a small bit of capacitive coupling to ground which is not very effective and very inefficient. If the rig was externally powered then the DC power leads and even the PS and AC lines help become an RF return for your wire antenna. If it were me, I would say next time try running a counterpoise wire right from the rigs ground connection (chassis ground) out along the ground. I'll bet even a short dipole or small closed loop antenna would have performed much better since they are ground return independent. You also may have had some other issues going on like a local broadband noise sources helping mask weaker signals. Were there other homes around you? Routers, pc's, plasma TV's, satellite receivers & DVR's, and all kinds or cordless contraptions generate tons of trash that pollute the HF spectrum. Gedas, W8BYA Gallery at http://w8bya.com Light travels faster than sound.... This is why some people appear bright until you hear them speak. ----- Original Message ----- From: Ian Baines To: flexra...@yahoogroups.com Sent: Tuesday, January 14, 2014 11:42 AM Subject: [FlexRadio] Flex 1500 with a long wire antenna I did a comparison of my Flex 1500 against an R75 receiver using a long wire antenna, fed via a unun and a coax cable. As a general HF receiver, it stacked up just about equally. So when I needed a receiver to take to Florida for the winter I took my Flex only, and a 40' long wire. What a disaster - no signals at all on HF. Not even WWV was audible. I could hear BC signals, but at low levels (S1 to S7). So I got to thinking - why is the Flex so insensitive with a high impedance long wire? All portable HF receivers work really well with a 40' long wire, but they have FET inputs and can handle match high Z antennas, as they are essentially voltage amplifiers. Obviously the Flex receives well with low Z inputs, such as coax but is completely unable to deal with a High Z long wire. It must be the converter chip that is insensitive to voltage, as it is a current amplifier. I can think of no other reason. Anyone else used a Flex for receive with a long wire (no coax, no coupler) as input? Live and learn, I should have brought one of my amplified whips with me. Ian VA3KAH __._,_.___ -------- Any and all comments and opinions stated here are those of the individual user and not FlexRadio Systems Your email settings: Individual Email|Traditional Change settings via the Web (Yahoo! ID required) Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe __,_._,___ _______________________________________________ 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/
