I use the XV 144 with the SDR1000. The XV 144 has to much IF gain for the SDR1000. To correct this I removed the MMIC U1 according to the Elecraft modification. I do use a mast preamp on 2m. 73 Maarten N1DZ
----- Original Message ----- From: "Dale Boresz" <[EMAIL PROTECTED]> To: "Roger Rehr" <[EMAIL PROTECTED]> Cc: <flexradio@flex-radio.biz> Sent: Tuesday, October 16, 2007 12:58 PM Subject: Re: [Flexradio] XVRX Input Port on Flex-5000 > Hello Roger, > > I have only a single Elecraft XV144 xvtr here, but I don't see any of > the noise that you're seeing on the XVTX/COM or the XVRX ports. However, > I do notice that the noise floor is about 7dB higher with a dummy load > connected to either of these ports, as compared to the RX1 or the ANTx > ports. Using the RX Meter on PowerSDR in the "SigAvg" mode, I measure > the following: > > w/ dummy load connected: > RX1 : -131.5 dBm > XVTX/COM : -124 dBm > > When I connect the Elecraft XV-144 xvtr to the above two inputs, I > measure the following (XV144 ant input connected to dummy load, and > XV144 powered ON): > RX1: -121 dBm > XVTX/COM: -121 dBm > > So, there is a fairly dramatic change in noise level if I power on/off > the XV144 while it is connected to the RX1 or ANTx inputs, but much less > when connected to the XVTX/COM. However, it's clear that the noise level > of the XV144 output exceeds the noise floor of the XVTX/COM port, so the > ultimate sensitivity is still determined by the XV144 xvtr. > > Have you tried connecting a 50 Ohm terminated BNC plug directly to the > XVTX/COM and XVRX ports so that you don't have a piece of coax acting as > a possible antenna? Do you still see the noise? Is it real noise, or are > they spurs (does toggling 'SR' on PowerSDR change their position?) > > 73, Dale > WA8SRA > > > > Roger Rehr wrote: >> Hi, All, >> >> I discovered a 'feature' of using the XVRX port that I at first thought >> was a software-signal-routing 'bug', which it is not. >> >> My station is VHF and up only, and is very heavily >> digitalized/computerized, with multiple concurrent pathways for RF and >> audio being used, all in the name of information control. It turns out >> that this is largely the root of the problem which I am about to >> describe. >> >> I discovered today that when I use XVRX as the receive input port to >> the Flex5000 from my transverters I get major digital noise that is the >> same across all 11 transverter bands from 50 MHZ thru 24 GHz, that I >> don't see if I use RX1-IN or ANT1 inputs for the transverters. >> >> If I uncheck 'Split RF' in the PowerSDR xvtr setup page and connect the >> receive cable to XVTX/COM, I get [of course] the same effect as if I >> was using 'split RF' and had the cable connected to XVRX: noise that >> is not present when ANT1 or RX1-IN is used. >> >> If I disconnect the coaxial cable bringing the transverter receive >> signal to the Flex5000 the noise disappears. I have found that much of >> the noise is coming from my SDR-IQ, which is also connected to the >> transverter line with a splitter, and is performing other necessary >> tasks for me. >> >> Not all of the 'extra' noise is removed when I disconnect the SDR-IQ. >> I suspect that the other noise is coming from other equipment in the >> environment and getting into my coaxial cable; it is unaffected by >> turning off the transverters. Some of it disappears when I turn off >> the FT1000MP [which is not connected to the coaxial cable], much of it >> remains. >> >> The difference between the results with XVRX and the other two input >> ports is in the bandpass filter on the RX1-IN and ANT1 inputs, I >> believe. >> >> In any event, the extra noise on the XVRX port [even without the >> SDR-IQ] reduces the utility of the transverter ports for me; I guess I >> will have to design/build a bandpass filter for the XVRX port before I >> can use it. >> >> To illustrate the problem, I have placed the info on a webpage at >> >> http://www.nitehawk.com/w3sz/flex5000-xvrx.htm >> >> that shows 4 appropriate screen grabs from PowerSDR: >> >> First, the PowerSDR screen with the 144 MHz transverter/Flex5000 >> receiving a 2 meter CW beacon at 144.285 using XVRX to receive the >> signal: >> >> Second, the Power SDR screen when feeding the same transverter signal >> in via the ANT1 port. Note the absence of the noise: >> >> Third, the PowerSDR screen when feeding the same transverter signal in >> via the RX1-IN port. Note the absence of the noise: >> >> Fourth, the PowerSDR screen when using the XVRX port but with the >> SDR-IQ disconnected from the splitter. Note that there is still quite >> a bit of noise that is not present when the ANT1 or RX1-IN ports are >> used. >> >> I hope that posting this will save someone else the trouble of chasing >> down the source of extra noise that he/she might see when using the >> XVRX port. If you have a noisy environment you may have trouble using >> the XVRX port without an external bandpass filter. >> >> You will need to save this email to retain the URL. It is not >> referenced anywhere on my website. >> >> 73, >> >> W3SZ >> Roger Rehr >> http://www.nitehawk.com/w3sz >> Roger Rehr >> W3SZ >> http://www.nitehawk.com/w3sz >> >> >> _______________________________________________ >> FlexRadio mailing list >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >> Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ >> FlexRadio Knowledge Base: http://kb.flex-radio.com/ >> FlexRadio Homepage: http://www.flex-radio.com/ >> >> >> >> > > > _______________________________________________ > FlexRadio mailing list > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > FlexRadio Knowledge Base: http://kb.flex-radio.com/ > FlexRadio Homepage: http://www.flex-radio.com/ > > _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
