In the thread “Tips and Strategies for more DX in SOTA Logs?” I recommended the use of 20m to work DX when activating because I believe there are a greater number of chasers having a beam antenna for 20m compared to those having it for 17m and 30m.
I’d ask you, SOTA chasers, to vote the following 3 polls saying which type is the best performing for DX antenna you have for chasing from your base QTH.
Please, do not vote about the antenna you are using for chasing from a SOTA summit.
These polls are only aimed to find out about chasers base station antennas.
One (slightly flippant) comment Guru. For me the best antenna for chasing from home is the only one I’ve got - a long wire. I wish my wife would let me have a beam!
Hi Andy,
Thanks for your vote.
Yeah, I think most of us wish our wives would let us have a beam…
I bought my tribander yagi+tower+rotator, etc when I was still single and thanks to that I can have a beam in my owned house, despite several frictions with my xyl from time to time.
But we moved to a rental appartment in town last summer and I don’t have any good perspectives about installing a beam in the appartment, so I live with a random wire endfed in the balcony. That’s why I voted wire and beam for 20m band, because I sometimes chase from my owned house with the beam I still keep there, but most of the times now I do chase from the appartment with the endfed random wire.
This poll is resulting highly interesting to me and I’d like as many chasers voting as possible, in order to have a more accurate result with less error margin.
However, we can already see what I was guessing of much greater number of chasers having a beam for 20m compared to those having it for either 17 or 30m.
Best 73,
Hi Guru, I use whatever antenna that gives me the best SNR. I am lucky to have an Ultrabeam (a dynamic antenna like the stepir that is a folded dipole on 40&30m and 2 elements all bands 20-6m), a Gap Titan vertical (all bands 80-10m), an 80m OCF (all bands 80-6m with tuner for WARC and 15m) and a 40m dipole, so pretty much have HFcovered. Like many though I do at times suffer from extremely strong powerline QRM and other interference from living in town - not much to be done about that short of cutting down power lines though!
Slighty off topic but given the number of antennas you have, have you considered a phasing unit perhaps using an antenna not meant for the band you are on and your main antenna. The non-resonant antenna will pick up the powerline QRM and you can then phase that with the other antenna to reduce the QRM.
Hi Ed, yes I have considered a phasing unit, but they are a rather expensive gamble on the off chance that it may fix the problem. Noise levels vary significantly and presently not bad depending on band/time of the day, so not too bothered presently.
I agree with Andy, there are plenty of circuits to build your own but if you want one ready built Here’s the one I bought built up from RA0SMS for €61 (US$75)
Has anyone here tested such QRM Eliminator and explain his/her own experience. Would it be, for instance, able to eliminate from my receiver the QRM produced by the LED lamps in my neighbour house or that produced by some of those phones battery chargers or the vitroceramic kitchen?
I’d immediately order a couple of them in case someone can say it works for such type of QRM.
Thanks.
73,
There’s no gaurentees Guru, which is why it’s probably an interesting project to build one. There have been articles on them in “Funk Amateur” and other radio magazines.
The principal of phasing signals from two aerials to remove QRM (note QRM, not QRN) has been around for many, many years.
Whether it will work in your specific case Guru, no one can say. By the way, I believe it’s not the LED lights themselves that cause the noise but rather the switched mode power supplies they run off. Have you tried running your gear off a battery in case the noise from your neighbour is actually coming up the mains leads - if so a Mains filter should stop that.
Hi Ed,
I think I recall having seen on the web some not very positive comments about these gadgets, however, it’s price is affordable, as I have seen you can even buy it as a kit for just 30€, and this makes it indeed an interesting project for trying one out, experimenting with it and seeing what it can finally achieve.
What I’ve read is they can cancel QRM coming from a single source, although it’s not possible for it cancelling multi sources QRM. The QRM produced by the battery chargers, the vitroceramic kitchen and the LED lamps of my neighbour are not coming up the mains leads, so I have the impression this gadget will be able to cancel it.
But I’d really like to hear from someone’s direct experience.
I might order one just to see how it does and I’d let you all know my findings, but it looks like they have run out of stock right now.
We’ll see if they produce more units soon.
Best 73,
I emailed Anton RA0SMS and he told me he’s awaiting some components and expecting to have them by next week. He’ll let me know and I think I’ll order one or two to get rid of some of those Switching Power Supplies QRM.
I’ll keep you informed.
73,
Thank you very much for your votes.
I found it very interesting and I got even surprised with a 14% out of 48 voting chasers having a beam for 30m. I didn’t expect this much.
The results for 20m met my expectations with a 45% out of 51 voting chasers having a beam. This is why I recommend 20m as the best band to try SOTA DX, simply because having so many beams around in the “Ocean of chasers” give the activator better chances to be heard and chased by a DX chaser.
The results for the 17m band are also nearly meeting my expectations with a 32% out of 55 voting chasers having a beam.
There must be many more chasers there who have not voted yet. If you feel like doing it and contributing to build these basic statistics, don’t wait and do it now.
Thank you.
Best 73,
“Has anyone here tested such QRM Eliminator and explain his/her own experience”
I’m a bit late to the party on this one as it’s quite an old thread, but here’s my two cents worth:-
I have really bad QRM at my location (currently S9+ on 40m & S7 on 20m) although it does drop down to S5 at certain times of the day.
I bought a second hand MFJ-1026 off of eBay in the hope that it would help. It works great for interference on spot frequencies and/or from a specific direction.
For example, my neighbours router used to wipe out 20m on 14 275 whilst leaving the rest of the band untouched. It worked fantastically at getting rid of that.
Unfortunately, most of the interference near me comes from all directions. There are around 5 mobile phone masts that I know of within less than a 1/4 mile radius of my house (probably more that I don’t know about) and I live in a mid-terrace on the edge of an estate, so literally hundreds of routers, power cables, ethernet powerline adapters etc.
It doesn’t manage to do anything about all of that crud. It now sits in the spare room doing nothing as it was more hassle than it was worth.
It depends what sort of noise you have and what you are trying to filter out.
Technology is great, but there is only so much that it can do.
Hi James,
Whether these units work depends a lot on the antenna you use as the “noise antenna”. What the unit does is to “phase” the signals from the two antennas so that the noise coming in on one port suppresses just that same noise component coming in on the other antenna. So your noise antenna needs to pick up the interference at a reasonable strength and then you “match” that against the main antenna and adjust it’s (amplified) level up to that of the interference on the main antenna. In theory all that is then left on the main antenna is the signals without the noise flattening them. Of course when you move frequency, you may need to retune the unit.
To set this up correctly is difficult and there are other downsides - these are great for SWLs but if you want to transmit, you need to make sure you don’t transmit through this unit - in fact it’s best to use on rigs with a separate receive antenna input.
Now if someone could come up with an Arduino (or other micro controller) based automatic tuning system for these devices, they could become very useful. But until then, mine is also sitting at the other side of the shack disconnected.
Mobile phone masts? Are you complaining about HF QRM or uwave QRM here as cell equipment and its installation is normally done properly and it’s not a serious source of QRM. Usually.
You need to fix all the noise sources in your own QTH first. This can be achieved. Then you need to DF the worst neighbouring sources and having fixed your own problems, enter discussions with your neighbours about applying the fixes to their devices or funding their replacement.
The only person who can materially affect the level of noise is yourself and you may find your neighbours are not interested even if you foot the bill.
I don’t really have a clue where it’s coming from.
I take Andy’s point about trying to track it down and entering into discussions with the neighbors.
Frankly there are literally hundreds of houses on this estate, including many extremely local ones with solar panels on the roof.
The statement about the phone masts may have been misguided but my point was that it’s probably not just coming from one source.
It’s probably a cumulative effect of many houses electronics added together. It doesn’t seem to be coming from one particular location.
Having tried to DF the source, I get more or less the same across the whole estate in any direction.
As mentioned in another post, I have 3 acres of farm land around 45 minutes from my house where I’m in the process of putting together a remote station.
When you consider that I hope to be moving out of Swindon within the next year or two, and I’ve got the option of using a remote station at a location with extremely low noise (around S0-S1 the last time I took my radios with me), it doesn’t really seem worth the effort of trying to track the various sources of noise and convincing my neighbors to let me fix problems which they probably hadn’t even noticed.
If I have an alternative solution for the interim which allows me to operate, why bother my neighbors. Especially when I have the space to set up a more effective antenna than I could in a mid-terrace garden.
Maybe that’s the wrong attitude to have, but just trying to take a realistic view of the situation.
