Tips for hearing VHF DX simplex QSOs (SSB, especially) - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: October 05, 2017, 11:58:59 pm
content: Does anybody have any tips for hearing people on any of the VHF (or UHF for that matter) bands communicating via simplex modes?I think I have had my best luck with experimental magnetic loop antennae. My tpical VHF/UHF antennas are vertical, how often do hams use horizontal polarization, do VHF DXers use horizontal yagis etc on VHF or is it less common now?Is it just dying out

author: denverpilot
author_rank: Regular Contributor
timestamp: October 06, 2017, 12:14:06 am
content: Most activity centers around contest and Net nights (if there is an active Net group in your area), and due to the nature of VHF+ and needing high gain and highly directional antennas, even listening into Nets can be hit or miss at your location depending on who the Net Control is, etc. Around here we have a fairly active Monday night group to tweak and tune things with but only two of the five Net controls run enough antenna and enough power for everyone to hear them. Practice in real Net skills (can’t hear everyone, need to get relays to tell folks you’re there so antennas can be pointed your way when it’s your turn, etc... required. It isn’t going to be like an FM repeater Net, that’s for sure.)As far as antennas go, I wouldn’t even attempt a magnetic loop at VHF and above. Lowest gain I would even mess with would be something like a “Big Wheel” for Omni and even then, I’m 40 miles or more from our closest participants in the area — low gain isn’t going to cut it. I’m all long boom yagis or nothing at all if I want to hear anyone, and pointed within 10-15 degrees of them. That said, pointed right at him I can work a ham over 100 miles away in another State (Kansas) regularly but we both have more than 100W on VHF and we both have high gain directional antennas.All the folks around here who are doing any serious contesting are horizontal. You’ll take a big hit being vertical, generally. Even a low gain square loop that’s horizontally polarized will get you at least heard if someone has their high gain stuff pointed your direction.I definitely don’t see many folks making “casual” contacts much above 6m. 6m and even 2m “open up” much more often than people think (DXMaps will show that) but people just aren’t there or have their antennas pointed the wrong way even if they leave the calling frequencies on low volume in the shack.That said, pingjockey and the WSJT variants are pretty popular for casual contacts. More so than SSB voice in my experience.Best: Contest weekends. ARRL VHF and CQ VHF being the biggest with ARRL UHF also in the list but much quieter.Second best: Find local contesters (look up scores online) in your area and see if they have a group for nets and weekly/monthly activity.“Dying out” not completely but most folks won’t go through the headaches of hanging a stack of yagis to talk on VHF+ or don’t have the room for them and those who do often spend the majority of their operating time on the air doing contesting since that’s when things are really active.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: October 06, 2017, 07:21:43 am
content: Find out when the activity sessions and nets are on in your local area.If you live in a dip find a local hill to set up on.Definitely use horizontal antenna polarisation.A 4 element yagi is small and quite easy to build.Follow VHF spotter websites or reports of improved conditions.It should be possible to hear well equipped stations up to 200 - 300km away. More if there's a bit of lift or you're well located.Here's an example of grabbing the portable station and running down to the nearby beach to catch an opening.

author: cdev
author_rank: Super Contributor
timestamp: October 06, 2017, 04:21:39 pm
content: VK3YE,Somebody should make a portable digital mode modem/keyboard (with CW keyer/decoder app as well) for smartphones, so people can get in on the fun when they find themselves with the opportunity.Might even work audio coupled to the rig but a plug connection would be better.What are the good VHF-spotter websites that are applicable to SSB? Does somebody need to be a member?PSKreporter.info is good for digital modes, that is good at showing when there is an opening.

author: TheSteve
author_rank: Unknown
timestamp: October 06, 2017, 08:04:30 pm
content: If you have the room a 2 or 3 element yagi for 6 meters can do amazing things when there is an opening.I have a Buddipole that can be configured as a 3 element yagi quite quickly that works great.

author: cdev
author_rank: Super Contributor
timestamp: October 06, 2017, 11:51:41 pm
content: So, this is some kind of "Transformer" antenna?Quote from: TheSteve on October 06, 2017, 08:04:30 pm

author: W2NAP
author_rank: Unknown
timestamp: October 07, 2017, 03:49:07 am
content: VHF+ weak sig "DX" is going to be horz. pol. so get some beams up (horz of course) also keep the feedline loss down as much as you can (means good quality feedline like heliax) also preamps at the antenna (again high quality no junk)as for activity, you never know what you will run into on the VHF+ SSB/CW weak sig. you could go days and hear nothing, then boom it opens up and you are working 500-1500mi and as quick as it happens it closes again.

author: TheSteve
author_rank: Unknown
timestamp: October 07, 2017, 08:37:31 am
content: Quote from: cdev on October 06, 2017, 11:51:41 pmPretty much. It's a portable antenna that fits in a carry bag. There are several variations and lots of pieces. Most people run them as a dipole or vertical. With enough pieces you can build a 3 element yagi. Sadly it isn't cheap.This is my setup for a VHF contest a while back, it's sitting on my back deck.

author: cdev
author_rank: Super Contributor
timestamp: October 07, 2017, 02:26:43 pm
content: That's a very good setup for 6M if you can put it up in a short amount of time, for a band opening or a contest, sure, I totally see that."Fine Business!"Which way did you have it pointed? I live on the East Coast of the US and I am wondering if people near me's signals ever make it into Western Europe on 6 meters?Maybe not so often now. Sporadic E, maybe.. Iceland??Definitely 10M though..

author: cdev
author_rank: Super Contributor
timestamp: October 07, 2017, 02:39:30 pm
content: (trying to think of higher gain horizontally polarized antennas I might be able to manage in a smallish yard)It might work to have two long poles for the front director and reflector and create a fixed direction Yagi between them..and string the whole thing between two trees, hanging. Kind of like old clotheslines did.Another thing that might work () might be a mini-size "rhombic" antenna on UHF, maybe using a wooden stick to hold the middle apart.Rhombics are freqency independent antennas that require the legs to be multiple wavelengths long.getting a resistor that was non-inductive at the desired range might be difficult?Although it sounds like a bit of an unusual approach, with a rhombic it might be possible to get a huge amount of gain. The back end could be anchored to a pole in the center (with a picnic table - perhaps the kind with umbrellas normally, under it for the operator) and the front end with its non-inductive resistor could be attached to a long wooden pole which could be moved to different points around the circle around the table - a sort of poor mans high gain beam for outdoors operation?Alternatively, a half rhombic (another traveling wave antenna, but unfortunately, vertical..) could be used terminated to ground at the far end, similarly with the far end being walked around in a circle to work stations in different directions.This sounds like potentially a lot of fun.

author: W2NAP
author_rank: Unknown
timestamp: October 07, 2017, 03:04:38 pm
content: Quote from: cdev on October 07, 2017, 02:39:30 pmim in a smallish city lot, I do have a 40' tower on the side, but I will have a 4 ele 6 meter beam up. a 13 ele 144mhz and a 19 ele 432 beam. these antennas are not big really. its not like HF

author: TheSteve
author_rank: Unknown
timestamp: October 07, 2017, 04:27:26 pm
content: Quote from: cdev on October 07, 2017, 02:26:43 pmThe antenna is pointed east. I am on the west coast of Canada. Last contest my furthest contact was Texas. With openings it is not uncommon for east coast stations to work Europe.Check out dxmaps.com for an idea of conditions per band.

author: cdev
author_rank: Super Contributor
timestamp: October 07, 2017, 06:54:05 pm
content: The RTLSDR is not such a useful receiver at 50-54 MHz because its just plagued by birdies in that range..In any case I dont think I have seen much activity on 6M where I live, ever.When i tune to it all I see are birdies. I need a better,more frequency specific- also horizontally oriented, antenna and I also should build some band pass filters specifically for 6m....Actually..thinking about this.. I have two canned oscillators that would do..(73.350 and 66.6667 Mhz)Assuming one works..I have a NE612N on a piece of veroboard with headers..So, I have a downconverter..That will be better than my rtlsdr for 6meters..when piped to my 1.8 MHz to 29.7 Mhz SoftRock and 24 bit capable sound cardby far the most sensitive receiver I have..I think the likely reason I have not been able to receive anything on 6m is that the receivers I have tried so far are not so good..I think the SR will likely do much better if I can downconvert 50-54 MHz to somewhere in the HF bands.that sounds eminently doable.

author: denverpilot
author_rank: Regular Contributor
timestamp: October 16, 2017, 01:14:12 pm
content: Quote from: cdev on October 07, 2017, 06:54:05 pmWhen 6 opens and there’s people present, you could receive most of it with a tin can and a piece of string.The two have to happen simultaneously, which is what’s made websites like dxmaps so popular. Most of us don’t have time to sit around all day calling CQ, but the fanatics and retirees seem to, and they spot the openings, and then people pile in.I think the neatest DX on 6 is aurora. When that happens, it’s truly magical. First time you hear it, you wonder why everyone is whispering. Being north of the equator, myself, you also find it fascinating that pointing the antenna north garners the loudest whispers.Radio is amazing.You’ll generally find the two requirements happen together more often in May and early June, because people are rigging up and testing things for ARRL June VHF.Just the law of averages. Once people are interested and operating again, and since Sporadic E tends to be a summertime phenomenon for the most part, 6m will have openings and people will be there to hear them, into July and August.As kids get ready to go back to school and people prep for winter, and all the usual fall holidays start, the band will open occasionally and you’ll only see a few die-hards making contacts on the online logs, etc.It’s just applied demographics. This is the wrong time of year for the best propagation AND finding operators on air. 6 will surprise you with openings, if you leave it on quietly in the background for a number of weeks and make an effort to make a CQ call every time you walk into the shack.I remember one deep winter evening, I asked a friend to help me test an audio issue across town. We chose 6 because we don’t hear each other on anything lower, shooting over the top of each other for the most part. Too far for ground wave.We are chatting back and forth across Denver for a few minutes about the audio issue, when a station in Virginia breaks in and we talked to him for over an hour. Huge opening, nobody on.Beacons can also be super-helpful if you’re trying to do things the old fashioned way instead of using modern internet and computer tools to alert you to band openings. Tuning around for beacons you know you normally can’t hear, and there they are.

author: cdev
author_rank: Super Contributor
timestamp: October 16, 2017, 02:31:16 pm
content: Are buildings.. i.e. Denver's highrises otherwise in the way? (or is it the curvature of he Earth- I need to take a look at Denver's size and particularly, sprawl.. LA is definitely large enough to do that.If the problems are buildings, I have a similar situation with NYC. I am in suburbia Not so very far from midtown Manhattan but far enough to have some green around me.This sounds good to know. So 6 meters enjoys some favorable characteristics as far as the "fresnel zone" perhaps?Aurora openings sound different than other band openings? Could you explain that in a little more depth? Ive always been interested in strange propagation conditions.. Ive heard a few.. echoes, fluttering/fadingHaving an SDR has given me a chance to take a lot of screenshots of interesting signal conditions.. That's a lot of fun. I have quite a few now.Quote from: denverpilot on October 16, 2017, 01:14:12 pmThank you for the suggestion. DXMaps seems like a good way to get a handle on what band conditions are.Since I posted this Ive found a number of workable horizontally polarized antenna ideas that I want to try out.I'm also working on an annunciation system to work in part by screen scraping web sites for info.For example, screen-scrape these web sites for the info needed to tell me when to check VHF bands out..then display those short, text based blurbs of information, as well as real SMS messages.. .An announcement system.. Most people would just use heir cell phones, but since I don't use my cell phone much, I want some other way to do a similar thing.

author: denverpilot
author_rank: Regular Contributor
timestamp: October 16, 2017, 07:37:28 pm
content: Buildings: Not as big a deal at VHF as UHF and above, but I live 40 miles southeast of Downtown in the prairie... so dirt and hills are more what I see than buildings. ;-)Height over average terrain is what counts — line of sight — until some form of other propagation kicks in.With Sporadic E, tropo, or even the rare aurora, the sky wave is being reflected (in simple terms) and the RF energy you focused directly at the horizon is still being absorbed by terrain. All antennas have some energy radiated at a takeoff angle higher than 0* to the horizon, so it works either way. So you’re usually designing for the most gain to the horizon for local contacts and the rest takes care of itself. More gain, more power, better receiver sensitivity (including when you get real serious about it, tower top mounted pre-amplifiers powered often via DC on the coax and using that for RX/TX switching along with really high quality RF capable relays, etc) — essentially you can keep throwing money at it as deep as your wallet will allow to squeak out a few more contacts in a contest.The good news for a beginner is that if there’s a contest fanatic or two around they’ll a) Almost always be able to hear you even if you initial attempts are weak, and b) probably have decades worth of older gear they’re storing as spares as they’ve thrown more money on the contesting bonfire, and they’ll often sell or loan out stuff to someone else who’s caught the bug.Going on up in frequency, getting into the microwaves changes things again.At 10 GHz, those contacts rarely go anywhere other than dish to dish, but one guy here worked all counties in the State by bouncing off of scheduled airliner service. With CW and a friend willing to drive — a lot. LOL. He does a neat presentation of how they could calculate the turbine engine RPM of the aircraft engines by looking at the modulation of the CW as it bounced to the other station on a scope or back to themselves after they decided to play with it some more. What they’d built was a rudimentary Radar.. of course.Dxmaps will send you alert emails. No need to screen scrape them. I think they ask for a small donation to keep stuff running.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: October 16, 2017, 07:53:37 pm
content: A very useful tool is athttp://heywhatsthat.comIt indicates your horizon from a location around 360 degrees. Actual distances worked can be 2 or 3 times that if not more. You can also identify obstacles in a path.This can show places you're likely to have a good or bad VHF radio path to and if picking good locations to transmit from, eg

author: denverpilot
author_rank: Regular Contributor
timestamp: October 17, 2017, 01:03:31 am
content: Quote from: vk3yedotcom on October 16, 2017, 07:53:37 pmThat looks like a fun day of operating!Someone should probably mention Summits on the Air, if the new folks are into hiking and the outdoors. I have a friend who’s a nut about that.And I know this guy as an acquaintance...https://www.youtube.com/user/goathikerHere’s my little bit of insanity from 2006 and 2007.https://photos.app.goo.gl/BTyIXZ3j3PfCQJbE22006 was a “full stack”, 2007 I experimented with a log periodic for all bands except 6 and 10 GHz. Both won me the Rocky Mtn Division rovers score, but the full stack was a lot nicer to operate. Less antenna switching and more gain.

author: cdev
author_rank: Super Contributor
timestamp: October 17, 2017, 04:07:47 am
content: You're going to laugh at my observation of the video.. My first thought looking at the picture was -- wow, they have winter in Australia!So, I am working on a small log periodic (its a trapezoidal tooth type LP) for high frequencies.Its very very easy to make. I will upload photos and a template in a couple of days. If somebody could test it out on higher frequencies that would be great. Its extremely easy to make with very little cost. I am using foam core but you could use cardboard.