Mark, Have a read of the September 2017 BVARC Newsletter -- The Radio Hotel column is about receive noise, etc. Also look at the referenced QST column.
Might help you in your quest. Rick -- W5RH On Mon, Feb 1, 2021 at 8:47 AM Mark Brantana via BVARC <[email protected]> wrote: > I will check all these things. > > Sent from my iPhone > > On Jan 31, 2021, at 10:16 PM, Doug SEYLER via BVARC <[email protected]> > wrote: > > > If you have. A battery powered sw receiver, check to see if it is present > there. If so, trip the main power to the house to see if it goes away. RFI > can be very broad banded. I’ve had power line noise that extends cripples a > lot of the spectrum. > > Doug W9LCQ > > Sent from my iPad > > On Jan 31, 2021, at 9:00 PM, Rick Hiller via BVARC <[email protected]> > wrote: > > > Although it is a Ham Band antenna for 40,20,10....you might try listening > to General Coverage and tune to 10, 15 or 20 MHz for WWV......see if you > can hear it.....from what you say, I doubt it, and if so, you have a radio > set up issue, IMHO.....Rick > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> > Virus-free. > www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> > <#m_1677128648540102546_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > > On Sun, Jan 31, 2021 at 8:45 PM Rick Hiller <[email protected]> > wrote: > >> Mark, A few questions, comments and tests: >> Sounds like a radio problem to me...so....not in any particular >> order, just what I thought of first to last.... >> . >> -- What S level is the noise? Does it change level with the RF Gain >> control? >> -- What if you disconnect your antenna coax? Does it go away? >> -- What if you connect a dummy load? Same noise? >> -- What does the Nano VNA show? Impedance wise (R and j) and SWR? What >> is the SWR bandwidth of the antenna across 40 and 20? >> -- Where is your RF Gain pot? Maxed? Try reducing the setting a bit. >> -- Do you have your "pre-amp" on? If so, turn it off. NB off too. >> -- What about CW mode....does the Narrow filter on make a difference? >> -- Where are the IF/PBT shift sliders set? They should be in the center >> for a base reference. >> >> -- Are the rear panel Receive Antenna In and Out jacks jumpered and is >> the jumper OK continuity wise? >> >> -- Is the Ham/General select switch in Ham position? I am not sure if >> the band pass filters are bypassed in General....just a guess. >> >> -- Take your coax off. Then using ONLY the center pin of the PL-259 >> insert it into the radio SO-239 center ONLY. Is the noise similar? Then >> screw on the PL-259 outside....does the noise change? Usually, using only >> the center pin causes lots of receive noise and then when you screw on the >> 259 outside the noise reduces as the antenna system is then a closed system. >> You can also do this with a 10 foot long piece of wire and just connect >> the wire to the inside center terminal of the SO-239 on the radio. The >> receive noise should increase when you touch the wire to the center >> pin......is this noise the same as you are complaining about? >> >> Have you run power to the antenna? What is the SWR? Similar to the >> Nano reading? Use the internal SWR meter and meter switch to select RF PWR >> and SWR set etc. >> >> That's about it for a 745 brain dump for tonight. Something is amiss >> in your set up, IMHO, no external wideband white noise source is jacking >> with ya. Sounds like receiver noise is at max gain and no received signals >> are being processed. >> >> GL and 73...rick -- W5RH >> >> >> >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> >> Virus-free. >> www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> >> <#m_1677128648540102546_m_8022499859921838938_m_5532074014698849640_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >> >> On Sun, Jan 31, 2021 at 7:33 PM Mark Brantana via BVARC <[email protected]> >> wrote: >> >>> I am reaching out for ideas on a radio issue. I have installed an IC-745 >>> Icom with an MFJ-2010 offset fed dipole. The power supply is a 20A MegaWatt >>> switching power supply, which is located right next to the radio. The >>> antenna is under some high power-lines with the long leg 90 degrees to the >>> power-lines. I used my nanoVNA to study the band SWR response, and >>> everything looks reasonable, though some small adjustments may need to be >>> made. Nothing is grounded as yet. >>> >>> Here’s my problem. I am only attempting to receive at this time and I >>> get consistent QRM white noise across all bands to the point where I can >>> barely pick out some voices, etc. >>> >>> >>> - I am confident that the antenna is properly connected due to my >>> antenna study. >>> - I don’t believe the power lines are an issue, since the problem >>> would likely be more isolated show up as birdies at certain frequencies. >>> - The radio settings seem to all be correct according to the manual. >>> >>> >>> - Lack of grounding, but again the white noise is generally >>> consistant across the spectrum. Still, this could be the problem. >>> - I have turned off my computer, so there no QRM from its power >>> supply. >>> - It does not help to have the switching power supply right next to >>> the radio, but other users give good reports on this model and no QRM >>> issues are mentioned. >>> - I tried the radio at different times of the day on 20-m voice >>> band, with the same noisy result. >>> - It could be the net result of a large number of small device >>> transformers, but I doubt it. >>> - I turned off the wifi, and still no change. >>> >>> >>> Hmm… I am a little stumped. Any thoughts or ideas? Personal experiences? >>> >>> Mark >>> N5PRD >>> ________________________________________________ >>> Brazos Valley Amateur Radio Club >>> >>> BVARC mailing list >>> [email protected] >>> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org >>> >> >> >> -- >> Rick Hiller >> *e-mail: [email protected] <[email protected]>* >> *Cell: 832-474-3713* >> *Physical: 9031 Troulon Drive* >> * Houston, TX 77036* >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> >> Virus-free. >> www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> >> <#m_1677128648540102546_m_8022499859921838938_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >> > > > -- > Rick Hiller > *e-mail: [email protected] <[email protected]>* > *Cell: 832-474-3713* > *Physical: 9031 Troulon Drive* > * Houston, TX 77036* > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > -- Rick Hiller *e-mail: [email protected] <[email protected]>* *Cell: 832-474-3713* *Physical: 9031 Troulon Drive* * Houston, TX 77036*
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