Reduce Noise Floor From S7 to S1 - Pull out those weak signals from the noise.

[@EI6DP]

When I trained as a Marconi RO (1969) the standard practice to reduce noise in a receiver was to reduce the RF Gain and to advance the Audio Gain sufficient for good audio reception, then use your RF Gain as your main Gain. Also if you suffer from static build up on your vertical you can use a 1meg resistor between the antenna and ground to bleed off the static. My vertical antenna is a GAP TITAN DX which I find great and its a very quiet antenna static-wise. I run my IC-7200 with the RF Gain way down and my Audio Gain to around 3 o'clock and use my RF Gain as my main Gain, either increasing or decreasing it when necessary which makes for a very quiet receive Great video. 73 de Ger EI6DP

[@yqtszhj]

Excellent point about the RF Gain and Audio Gain. That makes a huge difference too. Thanks for sharing the 1 Meg resistor tip also.

[@ethzero]

I'm very new to HAM and I was advised to crank the RF gain all the way up first. I'm literally reading this at 05:30 in the morning, I just fired up my IC-705 to try AF first, then RF gain and worked fantastically! The only thing that I had to tweak was the DB "REF" on the waterfall as mine was previously set to a permanent+20 dB. Thanks so much EI6DP! 73 de GB, M7VOK

[@EI6DP]

Hello Patrick - If you operate with the RF Gain fully advanced its akin to driving with your foot to the floor, *Everything* will be heard even a mouses fart. By reducing the RF Gain you are limiting what is being received, I should mention also to leave the pre-amp off unless you working a weak station. 73 de Ger

[@yqtszhj]

@EI6DP Thank you for the helpful contribution!

[@DD5LP]

Yep, agree. To high an RF gain makes noise worse. So if you can't change antenna, then backing off RF and increasing audio is a good idea. Especially on SDRs that overload very easily. 73 Ed

[@tincansailor9437]

I’m really glad I stumbled onto one of your earlier videos. I enjoy your content and presentation style. Wishing you success in growing your audience.

[@yqtszhj]

@@tincansailor9437Thanks. Just trying to put out information that may help others.

[@jeff-1weere]

I just subscribed. This guy's presentation style is superb. I don't want to badmouth other content creators, but this gentleman is mindful of the perspective of the viewer. A lot of videos point the camera in a general direction and say "that thing right there." People who are learning, like me, are thinking "what thing, where?" I watched this from beginning to end.

[@yqtszhj]

@ Thanks for watching. What you observed is my goal and I appreciate the feedback!

[@kd5txo]

Thanks for the report. If you would desire the same low noise on multiple bands: consider replacing your dipole with a horizontal loop skywire antenna for both transmit and receive....you would need to use a tuner for each band change, but you would get great performance. Just 275 feet of wire will get you 80 through 10 meters.

[@yqtszhj]

Thanks for the suggestion, I'll have to look into that.

[@psychodadsn]

I swapped out my endfed for a skyloop. About 2 s units drop in noise for me and they transmit well. Also, look at a loop on ground (log) antenna for receiving.

[@chrisg7veo495]

If you put the dipole in an inverted V config, just raising it up in the middle , it will still be quieter than vertical but also good for transmit too, give it a try

[@yqtszhj]

Thanks, I’ll give that a try.

[@chrisg7veo495]

@yqtszhj yes my inverted V just 15 feet height at the peak works great on 40m. Maybe material for another video.

[@billgoodson47]

What radio are you using? I am asking because I am interested in knowing about your display.

[@yqtszhj]

@@billgoodson47 I’m using the Yeasu FT-710. Most of the newer Yeasu HF radios offer the display port I believe. That was the very reason I picked it up since my eyesight is showing my age.

[@billgoodson47]

@ I have a 991 and have the same vision issue. That is why I asked.

[@leericelli_w8rnb202]

There are two transfer RX/TX boxes available on the market. DX engineering makes one the RTR-2 and MFJ used to make one- MFJ 1708. I own both and they work very well automatically changing between transmit antenna and receive antenna.

[@yqtszhj]

Those are nice. Did you buy any of the add on modules for the RTR-2? Just wondering.

[@johnwest7993]

You also get isolation from having a vertically polarized antenna and a horizontally polarized one. There can be as much as a 30 dB difference between horizontal and vertical polarization. I have severe noise problems at my downtown location, often over S-9 with a vertical, so I built a high Q tunable mag-loop for receive. I also use it for QRP transmit, though it's not designed to handle power. Over-all, if I was only allowed 1 antenna it would be a high-Q tunable mag-loop. It's small. It doesn't need to be tall, no guying or counterpoise requirements, and it's fairly quiet, (quieter than any other type of antenna,) no matter what the noise level at my location.

[@yqtszhj]

Excellent points on isolation. I need to try a mag-loop also, haven’t tried that yet.

[@thuff3207]

There are many type of receive antenna and they really help with noise. To fully take advantage of them a receive with a receive antenna input with a dual receiver makes it easy to use one. I have one on my radio and I am building a receive antenna.

[@daveborchard2019]

It looks like the vertical antenna is picking up a lot of noise. The noise tends to be vertically polarized. It’s amazing how well the resonant dipole works at only about 6 feet elevation. But the missing question is how does the horizontal 40 meter antenna compare to the vertical antenna for transmitting. Maybe you’d be better off to use the resonant 40 meter horizontal dipole for both transmitting and receiving.

[@yqtszhj]

@@daveborchard2019 Good question. I can and have used the dipole for xmit but it works more like a NVIS antenna coming in about 2 s-level below the vertical. In short I can talk to Texas and Ohio 400-500 miles away but I can’t DX to Europe. My noise is likely at least partially caused by an antenna farm on top of a mountain about 2 Miles from my location, along with all the noise from my neighbors. Wish I owned that ridge for sure.

[@stargazer7644]

@@yqtszhj It's also an NVIS antenna on receive.

[@kmh752]

My first thought was I wonder if there’s a way to make a foot switch do both functions. Meaning deactivated you’re listening on your dipole and activated it switches to the vertical and transmits at the same time. Eliminating the need to manipulate an extra switch. There would need to be multiple microswitches in the foot pedal. Just a thought. Thanks for your video.

[@yqtszhj]

@@kmh752 Good suggestion. Actually in the next video I’ll show how I have it set up where when I press the PTT it automatically switches to the vertical transmit antenna and disconnects the dipole. Releasing the PTT then switches it back to the dipole. Also I can lock it on antenna A, antenna B, or use A for transmit and B for receive. It has 3 options.

[@DuhBiggestDog]

Your dipole at 2M is an omnidirectional antenna. To maximize the readability I suggest you add a 20db preamp at the dipole feed. You will be amazed at the added readability you will have. However you must be sure to disable (or ground) the preamp when transmitting as your vertical is quite close to the dipole. You want to add it at the feed point so as to not amplify any noise that may be being picked up by the transmission line. Don K2PMC

[@yqtszhj]

Thanks for that suggestion. The dipole currently is disconnected completely from the feed line when transmitting also so disabling a preamp should be pretty easy. Good suggestion about putting it at the feed point also. Thanks!

[@bigken66]

How would that receive antenna do on a metal chain link fence?More noisey ? Or could the extra metal act as a counterpoise? Do counterpoises even exist on a horizontal wire antenna? I am a newb.

[@yqtszhj]

Good question and it would be something that I would try simply out of curiosity. It may depend on local noise sources but I would think it would ground out signals you’d want to receive, on the other hand if it by chance resonates on some frequencies then you may benefit. That’s why we’re always tinkering around. Plus there are so many variables at any location that what works at one location may not be ideal for another. Important thing being new is to enjoy the hobby, try something new, and keep learning. Don’t let any negativity spouted by others stop you from enjoying and learning. 73!

[@thomasmaughan4798]

Dipoles need distance from anything conductive, at least 1/4 wave but more is better. In rare circumstances you could use a chain link fence as a *reflector* and increase signal strength in a direction broadside from the fence. This would also reduce noise coming from the other side but shielded by the fence. You'd need some distance from the fence and depending on that distance you will have some pronounced lobes in the signal elevation. Dipoles do not use a counterpoise as such; each half of the dipole is counterpoise to the other half. Same with magnetic loop antennas. No counterpoise OR ground plane in that kind of antenna.

[@1crazynordlander]

I have two radios, an ICOM IC7300 on a ZS6BKW/G5RW antenna and the other a Yaesu FTDX10 on an EFHW-8010 antenna 10 feet off the ground. I never use the two at the same time for fear of doing damage to the receive radio. Can I somehow attenuate the receive antenna with a switch like yours while I am transmitting? I probably will replace the EFHW with a dipole like yours.

[@yqtszhj]

Ah, probably so. Stay tuned for the next video where I’m going to go over how I built the automatic antenna switch. In short I use the linear port on the radio (+13 volts, gnd, and PTT ground) to drive an optical relay bought off Amazon to switch the antenna.

[@michaelpolimer2128]

I would look at a loop on the ground (LOG) Rx antenna as well...........15' square of wire pinned to the ground with a little matching transformer..........I have two much more involved Rx arrays here, all home brew Shared Apex Loop and a 5 active element circle array. Both work to significantly reduce local noise, sometimes one is better than the other, sometimes neither is a significant improvement. My LOG also works and is abt as simple as you can get. You can also put down an array of LOG and phase them for directivity. Callum M0XXT (DX Commander) did some videos on the LOG as have several/many others.........agn, simple, easy, cheap.........73 Mike K1FNX near Boston

[@yqtszhj]

@@michaelpolimer2128 Thanks. I’ll be trying a LOG. I saw Callums videos about those and it was very interesting. I just haven’t made me a transformer yet but it’s on my list (list too long and time too short.j Thanks for sharing about your RX arrays.

[@jeff-1weere]

Same recommendation. I built a LOG and it is a fantastic receive antenna especially 40 and 80 meters.

[@ntokin]

Try to use t2fd antenna as a receive only instead of a classic dipole. You will see less noise without degrading of active signals due to the fact that t2fd is a short-circuited.

[@miker8379]

That would be pretty long for 40m

[@ntokin]

@@miker8379 Why? Standard AOR or Diamond t2fd are about 20 meters long that is equal to dipole setup which is used by topicstarter at the moment 2x10 m...advantage here is a wide frequency range and to receive only it`s quite effective with less noise.

[@vytenissciucka]

I think most of local noise is vertically oriented, therefore your vertical is noisy and low dipole is not. Low dipole should work worse on distant stations coming with low angles where properly built vertical should outperform low dipole.

[@yqtszhj]

I agree and good points. My findings so far at my QTH is that for receiving local stations (few hundred miles) the dipole is slightly worse. For long multiple hop signals (across the Atlantic for example) it makes little difference because after bouncing off the ionosphere we don’t know what the polarization is. I lose about one S-level on receive from Europe but my noise drops 7 so my S/N is greatly improved. Some interesting transmit results are that for NVIS the Dipole still works pretty well but on test from here to Italy, when my vertical gets to them at an S7, the Dipole is an S2 or S3 which is deep in their noise floor, which is to be expected. I was actually surprised they could copy me at all but they have much cooler stuff than I do.

[@johnrees44..G4EIJ]

Thank you..Brilliant!!..73..John

[@yqtszhj]

Thanks for watching and thanks for the comment.

[@mandytuning]

I found my monitor transformer was making a lot of noise on 80m and 40m . Wire it to the linear power supply and problem gone .

[@yqtszhj]

@@mandytuning Good information. Thanks!

[@ZzedZed]

2 hints: [1] dc ground the antenna [2] or put a big bleed resister on the ant/coax. don't use rg-58 its beyond useless.

[@yqtszhj]

Thanks for the tips. Been there, done those. My noise is things like my neighbors hvac unit too.

[@user-ef3nu1eh7z]

Keep in mind solar storms are at complete streaming constant these days some of that is ,killling radio

[@traderlarry]

Why does this work?

[@yqtszhj]

@@traderlarry In my simple mind it works like this. The theory says that when a horizontal polarized antenna is placed close to the ground it responds more to the vertically polarized signals only, because the ground mutes the horizontal signals. In my location my noise appears to be horizontally polarized and my 35 foot tall vertical picks up that noise. The low mounted dipole does not pick it up. I would think that the correct receive would have to be chosen by location because every situation is different. Now all that said, I might have got the polarization completely backwards and if so someone will chime in. Hope this helps answer your question.

[@ethzero]

thanks for the question.and the detailed answer!

[@user-ef3nu1eh7z]

Also multi band is fiber hlass as 11 mtr user my very is also fiberglass the actual ant is antron 99 encased fiberglass noise is vert none on horizantal you can hunt that noise

[@70looney]

just use 3 db att the rx is that good any way s6 will go down to s3 and the station will still be there dnr just take it off dont need it get some of the audio back with dnr off

[@yqtszhj]

@@70looney That does help, and when used in conjunction with the low mounted dipole it’s better. Thanks for sharing the tip.

[@stargazer7644]

Putting attenuation on receive reduces both the noise and the signal and worsens your receiver's noise figure. It does absolutely nothing to improve the signal to noise ratio. Attenuators should only be used when strong signals are overloading your receiver.

[@70looney]

@@stargazer7644 works for now i can work the station s1 s2 s3 with 3db att before i had s3 to s6 nosie floor heard nothing this is sdr has a very good rx 3 db att is nothing to it

[@yqtszhj]

@ Agree and thanks for commenting. The signal has to be greater than the noise to get any audible perceived benefit from any attenuation but is does nothing for signal to noise ratio as you have said. The beauty of the low mounted resonant dipole is it cuts the noise from S7 to S1 while the signal that is an S3 or S4 still comes through only now above the noise floor thereby improving the noise figure. Thanks for sharing.

[@stargazer7644]

@@yqtszhj Horizontal antennas can help with noise problems because most man-made noise sources are vertically polarized. Therefore horizontal antennas tend to be quieter. Having one so close to the ground will also greatly limit the antenna's sensitivity at low angles which is where nearby man-made noise usually comes from. Unfortunately that's also where long DX comes from so there are tradeoffs. The noise figure of a well designed radio is mostly set by the first amplifier and any attenuation placed before it. Antennas don't really change your receiver noise figure - they affect your receiver's gain. Noise figure represents noise added by your receiver's components to the incoming signal that degrades the SNR.

[@jamesgeorge1709]

It's known as a Beverage antenna and it for the most part it is not height sensitive.

[@brianfields4479]

Absolutely brilliant, works perfectly. Well done. 73 zl3xdj

[@yqtszhj]

Thank you sir. You provided the inspiration that gave me the motivation, and it has worked out well.

[@kd5txo]

Thanks for the report. If you would desire the same low noise on multiple bands: consider replacing your dipole with a horizontal loop skywire antenna for both transmit and receive....you would need to use a tuner for each band change, but you would get great performance. Just 275 feet of wire will get you 80 through 10 meters.

[@yqtszhj]

Thanks for that information!

[@DD5LP]

Yep sky loop is one of the quietest antennas around, plus it's easy and cheap to build. The only down side is that you need a lot of space. 73 Ed DD5LP

[@TheCrunchbird]

@@DD5LP You would have to puta sky loop up quite high to work DX on the lower bands, N2SN.

[@DD5LP]

@TheCrunchbird ideally at least a quarter wavelength above ground. My 40 m loop is at 9 metres high works well with grey line on 40m and long path into VK / ZL on 20m. So not quite a quarter wavelength high on 40m but still performs good for DX and EU. 73 Ed

[@TheCrunchbird]

@@DD5LP Thanks for the information. I live in a quiet rural area in NE Florida yet the noise from verticals is really bad here. I will give a loop a try, N2SN.