Re: [digitalradio] Regional communications ?
H, I have found 160-80 the best ground wave communications at night, for even short distances. You are correct in that the higher bands are useless for most short range stuff. I used to live 20 miles north of Athens, and it took me months to get even one contact on 15 or 10 with the city. Living in some very big cities around the world, it was always the 80-40 meter bands wherin I had the best (sometimes the worst QRM) communications locally. We had 2 meter repeaters in London, Hong Kong, and Caracas and I was on them, but not all that much. Driving in London once, the 2 meter repeater probably saved my life (or at least my car windows). I was new there, and it was during the time of the prison riots and one part of town (with the prisons) was up in flames. One of the locals talked me thru and out of the area when I had taken the wrong road. I was never so happy to get back to Abby Road, you couldnt sing about it. Danny Douglas N7DC ex WN5QMX ET2US WA5UKR ET3USA SV0WPP VS6DD N7DC/YV5 G5CTB all DX 2-6 years each . QSL LOTW-buro- direct As courtesty I upload to eQSL but if you use that - also pls upload to LOTW or hard card. moderator [EMAIL PROTECTED] - Original Message - From: Andrew O'Brien [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Tuesday, December 26, 2006 3:41 PM Subject: [digitalradio] Regional communications ? My entry in to amateur radio was via 10 meters and the quest for DX, I had no real interest in local communication. Over the years I have
Re: [digitalradio] Regional communications ?
Hi Andy, I use 80m for a regular phone SSB sked with a ham 190 miles away. 80m is quite reliable at night apart from static crashes and a generally high noise level. We had a recent night where phone QSOs were just about impossible with high QRN so we did some RTTY tests. I transmitted at various power levels 10 - 50 watts and my friend received on his Icom 756 pro II - and copy was extremely good at all power levels - so I expect that digital operations over that same path would work very well using just about any mode. My 80m antenna is an inverted-L 40m in length with an ATU running against a ground system - it is only about a 1/4 wave high so is NVIS by default. 73, Brett VK2TMG
Re: [digitalradio] Digital havoc with devices in car
Robert Chudek - KØRC wrote: Chuck, I will venture a guess you are using a trial version of the software because that is what I am hearing the voice say in the file you posted. 73 de Bob - KØRC in MN - Original Message - *From:* Chuck Mayfield - AA5J mailto:[EMAIL PROTECTED] *To:* digitalradio@yahoogroups.com mailto:digitalradio@yahoogroups.com *Sent:* Tuesday, December 26, 2006 2:48 PM *Subject:* Re: [digitalradio] Digital havoc with devices in car I recently downloaded and installed MixW2.17. The problem I am having is an USB audio burst that appears periodically in (apparently) both the received and transmitted audio approximately once each four seconds. I disconnected from the sound card and from the radio and recorded a sample into a wav file. Can anyone help me with this problem? I attached the sample, but am not sure it will accompany this message. 73, Chuck AA5J No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.15.28/604 - Release Date: 12/26/2006 12:23 PM Thanks, Bob. You are exactly correct! I thought I could at least *try* the trial version legally, but I guess I sprung a booby trap! Drats! The web page said I should try the trial version before I buy the full version. Do I really want to buy Mixw 73, Chuck
Re: [digitalradio] Digital havoc with devices in car
Hi Chuck, The attachment worked ok here for me. The sound seems to be saying 'trial' in a female voice. It sounds like a piece of applications software or your driver is doing this. Have you tried killing off processes using task manager to see if you can isolate what is causing it? 73, Brett -- === Brett Rees VK2TMG http://lisp.homeunix.net
Re: [digitalradio] SSB mixed with Mixw output?
Chuck, Well even with the new email header, the voice is still saying Trial... Trial... ;-) 73 de Bob - KØRC in MN - Original Message - From: Chuck Mayfield - AA5J To: digitalradio@yahoogroups.com Sent: Tuesday, December 26, 2006 3:09 PM Subject: Re: [digitalradio] SSB mixed with Mixw output? Sorry all. I should have changed the subject line on my last. I recently downloaded and installed MixW2.17. The problem I am having is an USB audio burst that appears periodically in (apparently) both the received and transmitted audio approximately once each four seconds. I disconnected from the sound card and from the radio and recorded a sample into a wav file. Can anyone help me with this problem? I attached the sample, but am not sure it will accompany this message. 73, Chuck AA5J
Re: [digitalradio] SSB mixed with Mixw output?
Robert Chudek - KØRC wrote: Chuck, Well even with the new email header, the voice is still saying Trial... Trial... ;-) 73 de Bob - KØRC in MN - Original Message - *From:* Chuck Mayfield - AA5J mailto:[EMAIL PROTECTED] *To:* digitalradio@yahoogroups.com mailto:digitalradio@yahoogroups.com *Sent:* Tuesday, December 26, 2006 3:09 PM *Subject:* Re: [digitalradio] SSB mixed with Mixw output? Sorry all. I should have changed the subject line on my last. I recently downloaded and installed MixW2.17. The problem I am having is an USB audio burst that appears periodically in (apparently) both the received and transmitted audio approximately once each four seconds. I disconnected from the sound card and from the radio and recorded a sample into a wav file. Can anyone help me with this problem? I attached the sample, but am not sure it will accompany this message. 73, Chuck AA5J HEE hee I thought it was say ing trash trash trash...
Re: [digitalradio] Digital havoc with devices in car
Thats interesting. I tried several earlier trial versions and all of them worked full bore for 2 weeks. After that, if you tried to use them, you got a pop-up that made you wait for a timer to reset before you could do anything more. They still worked if you didnt click on a spot, but that spot set the timer every time. Danny Douglas N7DC ex WN5QMX ET2US WA5UKR ET3USA SV0WPP VS6DD N7DC/YV5 G5CTB all DX 2-6 years each . QSL LOTW-buro- direct As courtesty I upload to eQSL but if you use that - also pls upload to LOTW or hard card. moderator [EMAIL PROTECTED] - Original Message - From: Chuck Mayfield - AA5J To: digitalradio@yahoogroups.com Sent: Tuesday, December 26, 2006 4:17 PM Subject: Re: [digitalradio] Digital havoc with devices in car Robert Chudek - KØRC wrote: Chuck, I will venture a guess you are using a trial version of the software because that is what I am hearing the voice say in the file you posted. 73 de Bob - KØRC in MN - Original Message - From: Chuck Mayfield - AA5J To: digitalradio@yahoogroups.com Sent: Tuesday, December 26, 2006 2:48 PM Subject: Re: [digitalradio] Digital havoc with devices in car I recently downloaded and installed MixW2.17. The problem I am having is an USB audio burst that appears periodically in (apparently) both the received and transmitted audio approximately once each four seconds. I disconnected from the sound card and from the radio and recorded a sample into a wav file. Can anyone help me with this problem? I attached the sample, but am not sure it will accompany this message. 73, Chuck AA5J No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.15.28/604 - Release Date: 12/26/2006 12:23 PM Thanks, Bob. You are exactly correct! I thought I could at least try the trial version legally, but I guess I sprung a booby trap! Drats! The web page said I should try the trial version before I buy the full version. Do I really want to buy Mixw 73, Chuck -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.15.27/602 - Release Date: 12/25/2006 10:19 AM
Re: [digitalradio] Digital havoc with devices in car
Brett Owen Rees VK2TMG wrote: Hi Chuck, The attachment worked ok here for me. The sound seems to be saying 'trial' in a female voice. It sounds like a piece of applications software or your driver is doing this. Have you tried killing off processes using task manager to see if you can isolate what is causing it? 73, Brett -- === Brett Rees VK2TMG http://lisp.homeunix.net http://lisp.homeunix.net Brett, I think it must be encoded in the Trial software somewhere. I hope it will not say Full every four seconds if I buy the Full version. Hmm? What software does everyone use for digital? 73, Chuck AA5J
Re: [digitalradio] Transmitting digital pictures on 14.240 MHz
Hi John After a direct mail with nonsense from some of you, my spam filter takes care of the most prominent wanna be lawyers on this group. They never reached my mail box. 73 de LA5VNA Steinar http://rfsm2400.aanesland.com non the mail server John Champa wrote: Steinar, I think US hams are simply reading far too much into their regulations. They tend to do that because we are over exposed: We have too many under-employed lawyers in the US, and way too many wanna bes. In the Army we called these amateur lawyers, barracks lawyers (HI). As a result they often over interpret fuzzy parts of regulations. And, they also over emphasize apparently clear parts of the same regs. Unfortunately, in this process, they often error on the excessively conservative side of the interpretation, thus frequently cutting their own radio experimental throats in the process. Always, when you talk with a FCC government official off-the-record and over a beer or at dinner, it is obvious to see that as long as nobody complains, they could not care less. This is especially true regarding Amateur Radio. However, most Hams are unable to see the light, thus the strange interpretations you will hear from US Hams. Vy 73, John K8OCL Original Message Follows From: Steinar Aanesland [EMAIL PROTECTED] Reply-To: digitalradio@yahoogroups.com To: digitalradio@yahoogroups.com Subject: [digitalradio] Transmitting digital pictures on 14.240 MHz Date: Sat, 23 Dec 2006 16:37:12 +0100 Hi my American HAM friends, If I have understood this right , this FCC rules of yours make it impossibility for you to use rfsm2400 as a keyboard to Keyboard mode. But you can use it for transmitting digital pictures on 14.240 MHz. It seems a little bit strange to me , but anyway ; let's try to exchange some pictures. I have tried this with a few european friends and it works great. I am qrv on 14.240 MHz from 17.30 utc until midnight local time. 73 de LA5VNA Steinar http://rfsm2400.aanesland.com
Re: [digitalradio] Regional communications ?
For this distance you can use 80 meters day and night, and 30m during daylight. I use 10 Watts and a 4x40m horizontal loop from home, and a 7.5 m linear loaded bended vertical on the camper. This works24/24 for distances from 20-100 miles. During night hours I use the pskmail server in Stockholm, which is 700 miles away. My 'local' server is 10 miles away, and I can work it day and night with 5 Watts on 30 meters using PSK125. It runs 25 Watts into a dipole. 73, Rein PA0R -Ursprüngliche Nachricht- Von: digitalradio@yahoogroups.com Gesendet: 26.12.06 21:48:51 An: digitalradio@yahoogroups.com Betreff: [digitalradio] Regional communications ? My entry in to amateur radio was via 10 meters and the quest for DX, I had no real interest in local communication. Over the years I have had hams ask me to help them set-up their stations for digital mode operation and have occasionally resorted to the lower bands in attempt to help them. Often my attempts to communicate with hams in a 10-50 mile radius has failed. During darkness, I skip over them, and during the day-light we can't hear each other. I know 10 and 20 meter daylight propagation characteristics like the back of my hand, but have no clue about what is normal for 80 and 40M . It seems odd to me that I would have to rely on 2M repeaters to talk to regional hams. What do others on this list do for regional communications on HF? It would seem to me that the digital modes would be ideal for regional use but whenever I get a chance to get someone brave enough to leave 2M chatting alone and try a digital mode on HF, I can't work 'em to help them get set-up. I am familiar with NVIS antennae but do not have a particular NVIS installation, I do not have real estate for 160M either. So what bands and regular antennas do you use for this ? -- Andy K3UK Skype Me : callto://andyobrien73 www.obriensweb.com DX Cluster telnet://cluster.dynalias.org Suggested Calling/Beaconing Frequencies: All frequencies are USB and assume a centre audio frequency of 1000Hz (e.g radio dial at 14.077.4 and 1000Hz on your waterfall = 14078.4) 20M: Primary : 14.078.4 Secondary: 14.076.4 30MPrimary: 10.142 Secondary 10.144 80MPrimary : 3583 Secondary: 3584.5 Yahoo! Groups Links -- http://pa0r.blogspirit.com DX Cluster telnet://cluster.dynalias.org Suggested Calling/Beaconing Frequencies: All frequencies are USB and assume a centre audio frequency of 1000Hz (e.g radio dial at 14.077.4 and 1000Hz on your waterfall = 14078.4) 20M: Primary : 14.078.4 Secondary: 14.076.4 30MPrimary: 10.142 Secondary 10.144 80MPrimary : 3583 Secondary: 3584.5 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Regional communications ?
--- Andrew O'Brien [EMAIL PROTECTED] wrote: My entry in to amateur radio was via 10 meters and the quest for DX, I had no real interest in local communication. Over the years I have had hams ask me to help them set-up their stations for digital mode operation and have occasionally resorted to the lower bands in attempt to help them. Often my attempts to communicate with hams in a 10-50 mile radius has failed. During darkness, I skip over them, and during the day-light we can't hear each other. I know 10 and 20 meter daylight propagation characteristics like the back of my hand, but have no clue about what is normal for 80 and 40M . It seems odd to me that I would have to rely on 2M repeaters to talk to regional hams. What do others on this list do for regional communications on HF? It would seem to me that the digital modes would be ideal for regional use but whenever I get a chance to get someone brave enough to leave 2M chatting alone and try a digital mode on HF, I can't work 'em to help them get set-up. I am familiar with NVIS antennae but do not have a particular NVIS installation, I do not have real estate for 160M either. So what bands and regular antennas do you use for this ? -- Andy K3UK For short ranges try 80 meters and a dipole up about 20 feet. The low antenna will tend to shoot the signal up so it will bounce back down. Also it will tend to be more omindirectional at this low heigth. I use one at this height to talk to some friends about 75 miles away. It is beter for this than an off center fed dipole I have at 50 feet for the near stations. __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: [digitalradio] Digital havoc with devices in car
Michael Hatzakis, Jr MD wrote: I’ve got a couple of TNC’s and radio’s in my car that I like to operate with backup battery after the car’s ignition goes off. I use a charging circuit to keep the battery charged when the car is running. This is my problem: when I start the engine, the ignition noise causes havoc with the TNC and other digital devices. Is it ignition noise or power glitches? What brand and model of TNC's are you using? Because some Kantronics TNC's may use an internal 9V battery as backup, and prevent the TNC to go nuts with the power glitches. Check the schematics of the KPC-3 and KPC-9612. I have tried chokes, filter caps etc. But the spikes are too broad. I tried a timed delay circuit for delayed switchover, but this causes too much complexity. I tried using a diode so devices can run on the filtered battery voltage while charging from the mains, but the voltage drop prevents proper charging. Did you use POWER Schottky diodes? They have lower voltage drop. It might be interesting to consider the power on switch of the FT-757, which uses a relay actuated by a circuit protected by a diode in series. The relay won't close with low voltage or reversed polarity. Any other ideas on how I can make this work? You have batteries, and you should not allow the starter to draw power from them. Otherwise, with no batteries, one large ESD (say, 1 farad @ 16 V) might help. It is what some people with large audio power amplifiers to have some local power reservoir close to their monster amplifiers. But if your problem are power glitches, and might very well be the case, you should isolate your radios and TNC's from the main battery during startup. How is the health of your main battery? Maybe a portable digital scope hooked on top of it might reveal what happens during startup...it is just a different kind of EKG... Jose, CO2JA DX Cluster telnet://cluster.dynalias.org Suggested Calling/Beaconing Frequencies: All frequencies are USB and assume a centre audio frequency of 1000Hz (e.g radio dial at 14.077.4 and 1000Hz on your waterfall = 14078.4) 20M: Primary : 14.078.4 Secondary: 14.076.4 30MPrimary: 10.142 Secondary 10.144 80MPrimary : 3583 Secondary: 3584.5 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Regional communications ?
Andy, NVIS simplified means a very high angle antenna and operating below the critical frequency. At mid latitudes it may mean 80 meters and lower frequencies. At my latitude (23 N) sometimes 40 meters qualifies. Of course, tricks may be done to enhance skywards radiation, like using wires below your antenna to mimic a 2 element yagi of sorts, I have read that three wires as counterpoise makes a good compromise. What you need is a cloud warmer, and operating below the critical frequency, where the ionosphere becomes transparent to your RFand you might get a looong DX reply from selenites or martians. Look on the Internet for f0f2 for your area, and choose a frequency somewhat below it. It is not advisable to go too low, as noise and D layer absorption will play against you. Jose, CO2JA --- Andrew O'Brien wrote: My entry in to amateur radio was via 10 meters and the quest for DX, I had no real interest in local communication. Over the years I have had hams ask me to help them set-up their stations for digital mode operation and have occasionally resorted to the lower bands in attempt to help them. Often my attempts to communicate with hams in a 10-50 mile radius has failed. During darkness, I skip over them, and during the day-light we can't hear each other. I know 10 and 20 meter daylight propagation characteristics like the back of my hand, but have no clue about what is normal for 80 and 40M . It seems odd to me that I would have to rely on 2M repeaters to talk to regional hams. What do others on this list do for regional communications on HF? It would seem to me that the digital modes would be ideal for regional use but whenever I get a chance to get someone brave enough to leave 2M chatting alone and try a digital mode on HF, I can't work 'em to help them get set-up. I am familiar with NVIS antennae but do not have a particular NVIS installation, I do not have real estate for 160M either. So what bands and regular antennas do you use for this ? -- Andy K3UK Skype Me : callto://andyobrien73 callto://andyobrien73 www.obriensweb.com
Re: [digitalradio] Regional communications ?
160, 80, 40 meters with almost any kind of wire/dipole antenna. We have a weekly regional net in the Sierra foothills in California on 80 meters, and never fail to copy everyone on the net. Scott/K6IX Andrew O'Brien wrote: My entry in to amateur radio was via 10 meters and the quest for DX, I had no real interest in local communication. Over the years I have had hams ask me to help them set-up their stations for digital mode operation and have occasionally resorted to the lower bands in attempt to help them. Often my attempts to communicate with hams in a 10-50 mile radius has failed. During darkness, I skip over them, and during the day-light we can't hear each other. I know 10 and 20 meter daylight propagation characteristics like the back of my hand, but have no clue about what is normal for 80 and 40M . It seems odd to me that I would have to rely on 2M repeaters to talk to regional hams. What do others on this list do for regional communications on HF? It would seem to me that the digital modes would be ideal for regional use but whenever I get a chance to get someone brave enough to leave 2M chatting alone and try a digital mode on HF, I can't work 'em to help them get set-up. I am familiar with NVIS antennae but do not have a particular NVIS installation, I do not have real estate for 160M either. So what bands and regular antennas do you use for this ?
Re: [digitalradio] SSB mixed with Mixw output?
I just downloaded a trial of MixW and there was nothing disturbing the audio. I do NOT think it is because of MixW being a trial version. Scott/K6IX Chuck Mayfield - AA5J wrote: Brett Owen Rees VK2TMG wrote: Hi Chuck, The attachment worked ok here for me. The sound seems to be saying 'trial' in a female voice. It sounds like a piece of applications software or your driver is doing this. Have you tried killing off processes using task manager to see if you can isolate what is causing it? 73, Brett -- === Brett Rees VK2TMG http://lisp.homeunix.net http://lisp.homeunix.net Brett, I think it must be encoded in the Trial software somewhere. I hope it will not say Full every four seconds if I buy the Full version. Hmm? What software does everyone use for digital? 73, Chuck AA5J DX Cluster telnet://cluster.dynalias.org Suggested Calling/Beaconing Frequencies: All frequencies are USB and assume a centre audio frequency of 1000Hz (e.g radio dial at 14.077.4 and 1000Hz on your waterfall = 14078.4) 20M: Primary : 14.078.4 Secondary: 14.076.4 30MPrimary: 10.142 Secondary 10.144 80MPrimary : 3583 Secondary: 3584.5 Yahoo! Groups Links
Re: [digitalradio] Regional communications ?
I've spent most of my ham career on or near 80 meters. The question depends on what part of the sunspot cycle you're in. If sunspots are at max, 40 meters is generally solid during the daytime hours for those distances. At nighttime, 40 meters gets long and you will need to shift to 80/75 meters for regional communications. When sunspots are at minimum (like now), 40 meters will too long for regional comms except at mid-day. 80 meters is pretty noisy during the day -- 60 meters works nicely but is USB only. After dark, 80 meters gets too long for regional comms, but 160 works nicely. For NVIS, a low dipole or inverted vee works fine - no need for a fancy antenna. You just want something that radiates UP. (Verticals radiate towards the horizon - nice for DX, but terrible for NVIS). There's a Yahoo group on NVIS that you might be interested in... also, there are websites where you can track the critical frequency - the highest frequency where a signal going straight up to the ionosphere will be reflected back. For NVIS, you generally want to be as close to the critical frequency as you can without being above it. Check out http://solar.spacew.com/www/fof2.html Andrew O'Brien wrote: I am familiar with NVIS antennae but do not have a particular NVIS installation, I do not have real estate for 160M either. So what bands and regular antennas do you use for this ?
Re: [digitalradio] Regional communications ?
Follow-up -- forgot 160m antennas. While a full-sized dipole or inverted vee is nice for NVIS, there are options for smaller lots. A full-size dipole is in the ballpark of 250 feet total length, but a full-size full-wave loop is only 60 feet or so on a side. Feed it either in the middle of one side or at a corner. It's fairly close to 50 ohm impedance, and you might even be able to get by without an antenna tuner if you restrict your frequency coverage (1.8 to 2.0 MHz is a 10% change in frequency!) and tune the antenna carefully. A shorter inverted vee will also work well on 160 -- the trick here is to *NOT* try to use coax cable for the feedline. With an antenna that's only half-size, the feedpoint impedance will have a low resistive component but will have a lot of reactance -- meaning the VSWR on the line will be terrible. Feeding with coax will result in all your power being consumed in feedline losses. To get around that, the two common tricks are to use the feedline as part of the radiator (short the inner and outer conductors together at the antenna tuner, and connect them to the antenna tuner long-wire output, feeding it against ground). The other (and, in my book, preferred) solution is to put up whatever size of dipole or inverted vee you can, and feed it with ladder line. Either trick requires a tuner that will handle 160 meters, though. Andrew O'Brien wrote: I do not have real estate for 160M either. So what bands and regular antennas do you use for this ?
Re: [digitalradio] Regional communications ?
Paul, A full sized 160 loop is not easy to set up since it needs to be around 500+ feet in circumference (1005 / 1.9 = 528 feet). This would make a square about 130 feet on a side. After comparing a nearly full size, low height (30 foot apex) 160 meter inverted vee to a very low (10 to 30 foot) L, the L was good enough that it worked for NVIS operation. It is directly connected to a multiband 80-6 meter ground mounted vertical but has quite a few radials up to 100 feet long and in the clear. If you use a dipole that is much smaller than 75% or so from full size, even with open wire line you can expect some substantial losses in the tuner. For example, using smaller than 180 feet for a 160 meter dipole can be lossy. It might be better to use linear loading or lumped inductances in the antenna. There are some hams giving out misinformation on low dipoles for NVIS operation, particularly on the NVIS yahoogroup. They believe that low dipoles only a few feet above the ground will give you a better S/N ratio and will actually work better for NVIS. I have done experiments with 80 meter inverted vee dipoles at 12 feet apex and 35 feet apex and the higher dipole is consistently superior than the lower dipole with just about any measurement you want to use, received signal strength, S/N ratio, and for sure, transmitted signal strength. The higher your horizontal antenna can be and still be below 1/4 wavelength, the stronger your NVIS signal. This means that you would have to exceed 60+ feet to be too high on 80 meters. Double that for 160 meters and half it for 40 meters. Needless to say, many of us have NVIS dipoles on the low bands without even trying:) 73, Rick, KV9U Paul L Schmidt, K9PS wrote: Follow-up -- forgot 160m antennas. While a full-sized dipole or inverted vee is nice for NVIS, there are options for smaller lots. A full-size dipole is in the ballpark of 250 feet total length, but a full-size full-wave loop is only 60 feet or so on a side. Feed it either in the middle of one side or at a corner. It's fairly close to 50 ohm impedance, and you might even be able to get by without an antenna tuner if you restrict your frequency coverage (1.8 to 2.0 MHz is a 10% change in frequency!) and tune the antenna carefully. A shorter inverted vee will also work well on 160 -- the trick here is to *NOT* try to use coax cable for the feedline. With an antenna that's only half-size, the feedpoint impedance will have a low resistive component but will have a lot of reactance -- meaning the VSWR on the line will be terrible. Feeding with coax will result in all your power being consumed in feedline losses. To get around that, the two common tricks are to use the feedline as part of the radiator (short the inner and outer conductors together at the antenna tuner, and connect them to the antenna tuner long-wire output, feeding it against ground). The other (and, in my book, preferred) solution is to put up whatever size of dipole or inverted vee you can, and feed it with ladder line. Either trick requires a tuner that will handle 160 meters, though.
Re: [digitalradio] Regional communications ?
KV9U wrote: Paul, A full sized 160 loop is not easy to set up since it needs to be around 500+ feet in circumference (1005 / 1.9 = 528 feet). This would make a square about 130 feet on a side. Yep. I was thinking of the 80 meter one. At 130 feet or so per side, it's pretty big, but still fits in some lots where there's not enough length to do a 160 dipole. I really should restrict things that require thinking to before 5:00 PM when I switch the brain in standby after work... After comparing a nearly full size, low height (30 foot apex) 160 meter inverted vee to a very low (10 to 30 foot) L, the L was good enough that it worked for NVIS operation. It is directly connected to a multiband 80-6 meter ground mounted vertical but has quite a few radials up to 100 feet long and in the clear. If you use a dipole that is much smaller than 75% or so from full size, even with open wire line you can expect some substantial losses in the tuner. For example, using smaller than 180 feet for a 160 meter dipole can be lossy. It might be better to use linear loading or lumped inductances in the antenna. There are always compromises. My dad's running a 75-meter inverted vee fed with open-wire line and an LDG auto-tuner. It works quite well on a 100-mile path near the top end of 160 meters. (It also works quite well at resonance until it's too long after dark and there's no more NVIS propagation that high in frequency!) There are some formulas out there somewhere for computing the necessary loading coils to make short dipoles - I used to have an old DOS program that would do it. Google will probably find an up-to-date version - and as you state, that's probably the best solution. Put up an inverted vee that's as long as the lot allows, and put a loading coil in it to resonate it on 160. Add a tuner to get some reasonable bandwidth and to compensate for the 50-ohm feedpoint impedance. There are some hams giving out misinformation on low dipoles for NVIS operation, particularly on the NVIS yahoogroup. They believe that low dipoles only a few feet above the ground will give you a better S/N ratio and will actually work better for NVIS. I have done experiments with 80 meter inverted vee dipoles at 12 feet apex and 35 feet apex and the higher dipole is consistently superior than the lower dipole with just about any measurement you want to use, received signal strength, S/N ratio, and for sure, transmitted signal strength. There *is* a limit to what low is for it to work. Get too close to ground, and run into trouble. A 35 foot apex on an inverted vee is still considered low (1/8 wavelength at the top) And at 160, a 35 foot apex is even lower (in wavelengths). My dual-band 80/160 inverted vee is about 40 feet at the apex, and works quite well for NVIS on both bands. The higher your horizontal antenna can be and still be below 1/4 wavelength, the stronger your NVIS signal. This means that you would have to exceed 60+ feet to be too high on 80 meters. Double that for 160 meters and half it for 40 meters. Needless to say, many of us have NVIS dipoles on the low bands without even trying:) That's a fact that's most often overlooked on the NVIS group. They're always asking things like how do I use the NVIS mode? when the fact of the matter is that if they're communicating at all at the frequency and distance they're talking about, they're already doing it :) NVIS has become somewhat of a buzz-word, when it really shouldn't be. It's not magic or anything super-special or complex. It's simply how things work and have been working for all those years before it became a popular subject on internet discussion groups... Thanks for the correction on the loop size... 73, - ps
Re: [digitalradio] Regional communications ?
Andy- My recommendation would be 6M. We have a local net thatcovers a radius of over 50 miles, at night. Sometimes MUCH more. The antenna I find most effective is a Yagi with a low F/B (Normally considered to be a lousy antenna) I point toward the center of the net area, and only move if someone wants a relay. Of course, with a single station sked, more focus will help. Actally, 10M seems to be better here than your experience. When I scan the beacon frequencies, I frequently see low power stations at 50 miles or more. I DO have a low noise area, though, at the highest point in several miles. Good luck-Bill-W4BSG At 02:41 PM 12/26/2006, you wrote: My entry in to amateur radio was via 10 meters and the quest for DX, I had no real interest in local communication. Over the years I have had hams ask me to help them set-up their stations for digital mode operation and have occasionally resorted to the lower bands in attempt to help them. Often my attempts to communicate with hams in a 10-50 mile radius has failed. During darkness, I skip over them, and during the day-light we can't hear each other. I know 10 and 20 meter daylight propagation characteristics like the back of my hand, but have no clue about what is normal for 80 and 40M . It seems odd to me that I would have to rely on 2M repeaters to talk to regional hams. What do others on this list do for regional communications on HF? It would seem to me that the digital modes would be ideal for regional use but whenever I get a chance to get someone brave enough to leave 2M chatting alone and try a digital mode on HF, I can't work 'em to help them get set-up. I am familiar with NVIS antennae but do not have a particular NVIS installation, I do not have real estate for 160M either. So what bands and regular antennas do you use for this ? -- Andy K3UK Skype Me : callto://andyobrien73 www.obriensweb.com DX Cluster telnet://cluster.dynalias.org Suggested Calling/Beaconing Frequencies: All frequencies are USB and assume a centre audio frequency of 1000Hz (e.g radio dial at 14.077.4 and 1000Hz on your waterfall = 14078.4) 20M: Primary : 14.078.4 Secondary: 14.076.4 30MPrimary: 10.142 Secondary 10.144 80MPrimary : 3583 Secondary: 3584.5 Yahoo! Groups Links
