Topband: Loading coil current distribution
Thanks Dave KH6AQ for the reference to Tom W8JI's article on loading coil currents. I just re-read it and it makes interesting reading. As I thought, he showed that current out of a loading coil is essentially the same as the current into it. However the results shown in the QEX article pointed out by Rick N6RK don't seem to agree with Tom's, maybe because Tom constructed a pair of all-plastic RF ammeters which didn't affect the loading. Quote by W8JI: <*Measuring the current into and out of the loading coil with a small thermocouple RF meter, I detect no difference This is in close agreement with the model*.> Of course as has been pointed out, there is bound to be some loss through the coil. The original question was how to match a sloper which is shorter than a quarter wave length. If possible I believe it is better not to use inductive loading at all, but to extend the top of the antenna making it a full quarter wave sloping inverted 'L', which is what I have. Better still, two top wires as a 'T'. My inverted 'L' has its 90 ft vertical section supported by a tall tree. It slopes away from the tree in order to minimise absorption by it. Also it is slightly longer than a quarter wave making it slightly inductive and is matched to the 50 ohm coax by a parallel fixed capacitor acting as an L-match. This also has the advantage that the point of maximum current is some way up the 'vertical' section. All good stuff. 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Topband Digest, Vol 259, Issue 14
Sorry Jim K9YC but it is incorrect to say that a loading coil at the base of an antenna, which is less than a quarter wave, will affect the high current point of the antenna. Assuming the coil is pure L with no distributed C, the current exiting the coil will be the same as that entering it. It is simply another way of matching the antenna to the feeder. However I'm sure you are right to say it's more convenient to accept the slight loss in the feeder and to tune it in the shack. I think it was W8JI who went to great lengths with two thermocouple RF ammeters to prove the currents were the same at the top and bottom of his mobile antenna loading coil. 73, Tom G3OLB On Sun, 28 Jul 2024 at 05:03, wrote: > Send Topband mailing list submissions to > topband@contesting.com > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.contesting.com/mailman/listinfo/topband > or, via email, send a message with subject or body 'help' to > topband-requ...@contesting.com > > You can reach the person managing the list at > topband-ow...@contesting.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Topband digest..." > > > Today's Topics: > >1. Quarter wave sloper ? (jim.thom jim.t...@telus.net) >2. Re: Quarter wave sloper ? (Felipe J. Hern?ndez) >3. Re: Quarter wave sloper ? (Gene Smar) >4. Re: Quarter wave sloper ? (jim.thom jim.t...@telus.net) >5. Re: Quarter wave sloper ? (Gene Smar) >6. Re: Quarter wave sloper ? (Tree) >7. Re: Quarter wave sloper ? (Rick Kunath) >8. Re: Quarter wave sloper ? (Rick Kunath) >9. WG: AW: Quarter wave sloper ? (dj...@t-online.de) > 10. Re: Quarter wave sloper ? (Felipe J. Hern?ndez) > 11. Re: Quarter wave sloper ? (Jim Brown) > 12. Re: Quarter wave sloper ? (Jim Brown) > 13. Re: Quarter wave sloper ? (jim.thom jim.t...@telus.net) > 14. Re: Quarter wave sloper ? (Jim Brown) > > > -- > > Message: 1 > Date: Sat, 27 Jul 2024 12:47:51 -0700 > From: "jim.thom jim.t...@telus.net" > To: topband@contesting.com > Subject: Topband: Quarter wave sloper ? > Message-ID: > < > cab4zmgu5-mk94mjy9khpmf_a-1kyg5px6fulxb1k2mvqofm...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Has anyone had success with a 160m, 1/4 wave sloperhanging off a 90' > tower, with a 40m yagi just above the top of the tower ? > > > -- > > Message: 2 > Date: Sat, 27 Jul 2024 15:50:23 -0400 > From: Felipe J. Hern?ndez > To: "jim.thom jim.t...@telus.net" > Cc: topband@contesting.com > Subject: Re: Topband: Quarter wave sloper ? > Message-ID: > 4walcja6xmwo6vr5f5jmqid...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Yes, is a great performer, don?t waste your time with inv v or sloping > dipoles, is a little trickier to tune but it?s a fantastic radiator. > > Felipe > Np4z > > On Sat, Jul 27, 2024 at 3:48?PM jim.thom jim.t...@telus.net < > jim.t...@telus.net> wrote: > > > Has anyone had success with a 160m, 1/4 wave sloperhanging off a 90' > > tower, with a 40m yagi just above the top of the tower ? > > _ > > Searchable Archives: http://www.contesting.com/_topband - Topband > > Reflector > > > > > -- > > Message: 3 > Date: Sat, 27 Jul 2024 20:35:24 + (UTC) > From: Gene Smar > To: "jim.thom jim.t...@telus.net" , > > Subject: Re: Topband: Quarter wave sloper ? > Message-ID: <10192229.543199.1722112524...@mail.yahoo.com> > Content-Type: text/plain; charset=UTF-8 > > Not exactly, but close. I installed an 80M 1/4 wave sloper (a/k/a > half-sloper) wire off my 64 foot tower at 50 feet. Above the wire at 66 > feet is a? Bencher Skyhawk tribander where I shorted all the parasitic > elements to the boom for extra top-hat loading. The sloper seems to be > pretty broadbanded and I can work into the Canadian maritime provinces and > UK and western Europe pretty regularly from Maryland with 100 Watts. > FWIW. > 73 de?Gene Smar AD3F? > > Sent from my Radio Shack TRS-80 model 100 laptop > > On Sat, Jul 27, 2024 at 3:48 PM, jim.thom jim.t...@telus.net< > jim.t...@telus.net> wrote: Has anyone had success with a 160m,? 1/4 > wave sloperhanging off a 90' > tower, with a 40m yagi just above the top of the tower ? > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > > > -- > > Message: 4 > Date: Sat, 27 Jul 2024 13:36:57 -0700 > From: "jim.thom jim.t...@telus.net" > To: Felipe J. Hern?ndez > Cc: topband@contesting.com > Subject: Re: Topband: Quarter wave sloper ? > Message-ID: > 21kx+7szeh1...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > Tnx for the quick response. > > Is a CM choke required at the feedpoint ? > If I can't fit the entire required length of wire,(I think I ca
Topband: QRP on 160?
For many years after I was licensed in 1960, we were limited in G-land to 10 watts input to the PA (not output). So working DX was a major achievement, although there were quite a few 'fat watts' around! G3PU used to regularly work VK and ZL with a genuine 10 watts from his cliff top QTH on the south coast. G3ERN was another genuine 10 watter who worked VK/ZL. Somewhere in my log there is a QSO with George AA7JV when he was running 5 watts in Miami with an excellent signal. 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: ARRL DX CW Contest
Best top-band conditions I've heard in a while. Mid-West and West Coast romping in both mornings, including CA - N6RO and WA6KHK. 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Inverted-L Question
Steve, For comparison my inverted-L is similar to yours with a 94 ft vertical section and 43 ft horizontal (ish). It is on a tall tree, not a tower. Like you, I use an L-network to match it and get a feed impedance on 1826.5 KHz of 50+j0. I have a 1600pF capacitor in parallel but no inductor as I simply extended the antenna length to make it slightly inductive. 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: ZL1AZ
Good signals peaking at my sunrise this morning from Dennis ZL1AZ. Nice to hear 160 conditions improving. 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Unsubscribing
Hello Greg, Just to say thanks a million for the countless 160 metre QSOs we have had, mainly at UK sunrise, over the past 15 years. Your remote station receiving capability has always amazed me. I can imagine your frustration at hearing and copying us so many times, when we were not hearing you. Sometimes it was the other way round. Proof enough that one way propagation does exist on 160. I won’t be joining you on microwaves, but if you do decide to set up a 160 remote facility again in Cape Town, I will be listening for you! We hope to visit ZS1 again when these travel restrictions are lifted and when we do, we will certainly get together. Best 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Topband Conditions
Just to add to the discussion on band conditions, Mike W4EF near LA was romping into UK this morning, Tuesday at 0800 sunrise, peaking 8 to 9 and Larry N7DD was well over the 9. Apart from those two, the band was devoid of CW during the short time I was on. 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: DXE Thunderbolt
David G3WGN, I'm sure you must have some tall trees down there in the Dart Valley! You could save yourself a bundle in shipping charges alone by putting up a simple wire inverted 'L' or a 'T'. Use a pneumatic tennis ball launcher to place the halyard over the tree at the highest point. I have one of these and will even come down and do it for you as you're not far away! My 'L' is 90 feet up and 43 feet out to another tree. It is matched at 1825 KHz by a simple 1,600 pf high voltage ceramic capacitor as an L-network from base to the radial field. These caps are hard to come by these days, so rather than making the antenna slightly longer and inductive, it is probably better to make it slightly shorter and capacitive and then matching with a small shunt inductor, known as a 'hairpin'. Look forward to hearing you on 160! 73 Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: 160 conditions
It's nice to hear the band back in good shape again after a few years. Big CW signal from W4EF in CA this morning along with ZL3IX, also a string of JAs/HL earlier this week. Let's keep the 160 CW activity up! 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Safety with pneumatic tennis ball launchers
G4FTC wrote "The one thing that scares me with the tennis ball launcher is the risk of the plastic air reservoir exploding..." - which is why I always put on safety goggles when using mine. 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: 160 conditions
Outstanding sunrise conditions at 0800 today on top band. FM5BH on 1818 KHz S9+. ZL3IX on 1826.5 long path peaking S8/9 on my meter. RBN skimmers showing excellent path to USA but very little other activity. Come on guys, turn that computer off and plug the key in! 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Poor conditions in 2018??
I have to disagree with Steve VK6VZ and Dave W0FLS about conditions so far this season on topband. Although talking about different paths and times, regular daily long path skeds between myself with several other G's and ZL3IX, have been remarkably successful and I have logged 23 completed QSOs since 21st September this year. That's not quite a complete Q per day, but taking into account the days one of us didn't show up, it's not far short! Also, the RBNs have indicated good propagation to USA/Canada most days at UK sunrise. West coast stations have been conspicuous by their absence though, with the exception of a couple of big signals from AZ and AB. US activity is not particularly good at our sunrise, probably explained by most folks needing 8 hours sleep! 73, Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: 160m Parasitic array (VE6WZ_Steve)
Fascinating presentation Steve, thank you. Tom G3OLB _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Topband conditions
A couple of hours this morning on 160 CW yielded FR4NT, VE6WZ and ZL3IX as well as some other old friends, so considering the high static levels, conditions are pretty good! 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Capacitive vs. Inductive Matching of Inverted 'L'/'T'
I used to use a slightly shortened 'L' with a small inductor at the base until I was told by LA5HE that he could hear me on 80 as well as 160! Using capacitor matching forms a low pass network which will reduce harmonic radiation. The inductor method forms a high pass L-network. BTW, why is it called a 'hairpin' inductor? Looks nothing like a hairpin, or does it? 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Air wound coil
Bob W7RH - you don't need expensive hard-to-find vacuum capacitors to match a quarter wave 'L' or 'T' on top band. I use cheap multilayer high voltage disc ceramics and these have been working perfectly at QRO levels with my inverted 'L' for years. I use 1600pF made up from 1000pF + 470pF + 220pf all rated at 6.3KV and available (over here) from CPC at less than $4 for 10. Antenna is slightly longer than a quarter wave so it is inductive and the capacitors form the other part of the L-match network. 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Top band sloper resonance
Gary KA1J, It struck me that maybe you originally cut your sloper a little longer so you could match it with a simple capacitor. My inverted L is resonant on its own, somewhere down in the 1.750 region. It’s effectively matched to 50 ohms by an L network but the series inductance part of the network is made by lengthening the antenna a little. I have a parallel high voltage ceramic capacitor from the feed point to radials. I can’t check the actual values because I’m currently on vacation in W4 land. 73, Tom G3OLB Sent from my iPhone _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Wednesday activity night
Roger G3YRO – conditions haven’t been all bad on 160 lately. ZL3IX and I have had 7 good long path QSOs in this month so far. 73, Tom G3OLB Sent from Mail for Windows 10 _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: 160 activity night
Sorry guys, I thought I posted the following about a month ago. Must be a long delay echo on the 160 reflector! Tom G3OLB Just to say that I wholeheartedly endorse Roger's comments on repeat 160 metre contacts. We are not all certificate hunters and many are only too happy to rag-chew. In 58 years on top band, I have no idea of my DXCC score but it's quite a few. So please Mark K3MSB and all you others who are frightened of answering CQs from someone you may have worked before, if you hear us on please give us a shout even if just for old times sake! Don’s (WD8DSB) experience is very sad and the other guy must be a complete moron. How long does it take for a minimal QSO, RST + name? I'm not sure I can climb out of the sack at Z or 0300Z on a Wednesday though Roger! Sent from Mail for Windows 10 _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: 160m DX Activity Night
Just to say that I wholeheartedly endorse Roger’s comments on repeat 160 metre contacts. We are not all certificate hunters and many are only too happy to rag-chew. In 58 years on top band, I have no idea of my DXCC score but it’s quite a few. So please Mark K3MSB and all you others who are frightened of answering CQs from someone you may have worked before, if you hear us on please give us a shout even if just for old times sake! Don’s (WD8DSB) experience is very sad and the other guy must be a complete moron. How long does it take for a minimal QSO, RST + name? I’m not sure I can climb out of the sack at Z or 0300Z on a Wednesday though Roger! 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: D10 Field Telephone Cable
Vic/David – looks like D10 field telephone cable may be readily available at: http://armyradio.com/800-Meters-DON-10-WD1-TT-D-10-Twisted-Pair-Telephone-Cable.html GBP 64.50 for 800 metres sound a pretty reasonable price to me. 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Conditions improving
Really good to hear 160 conditions getting better by the day! Greg ZL3IX was peaking 569 running only 50 watts on long path at my sunrise today. Forget the digital modes and start bashing that key! 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Jeff's Book
Just to say I received my copy of Jeff's 'DXing on the edge' today, complete with 19 chapters, bought from 'Book Depository' via Amazon. Price including shipping was GBP 15.26. Now for some interesting reading! 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: 160 M Inverted 'L'
Folks, You don’t need expensive vacuum capacitors or bread slicers/toast racks to match your 160 metre ‘L’. I use a low pass L-network consisting of 0.95 microhenrys in series and 1600 pF in parallel with the coax. The inductor is not real and is made by slightly extending the length of the antenna, which is 90 ft up and 46 ft horizontal. The 1600 pF cap is made up of several high voltage 6.3 KV disc multilayer ceramic capacitors in parallel. These are readily available and cost 2 or 3 GBP each from CPC/Farnell (CA05041 series made by Murata). I have been using this arrangement for some ten years at significant power levels without any failures. 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: 80-160M remote autotuner needed (Mike DeChristopher)
Mike, I just can’t figure out why you would use 807s in a remote tuner! 73, Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Laurel & Hardy
Frank, Interesting that in the 1930s you folk in the colonies called the thing an “aerial” and not an “antenna”! 73 Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: BCB Interference
Rather than use a filter capable of handling the transmit power, surely a better solution for the K3 would be to use a separate 160m receiving antenna, via a small filter on the BNC auxiliary antenna input. 73 Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Slick Contest Operation
..sorry, posted to wrong reflector! _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Slick Contest Operation
G4FKA: What do you mean 'Once upon a time'? Have you listened on 160 lately? Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Digi Mode Spurious Issues
W8JI said: .as did KW with their KW2000 over here. Tom G3OLB _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Balun Question
Gary KA1J - take a look at this excellent article on ferriste baluns by GM3SEK: http://www.ifwtech.co.uk/g3sek/in-prac/inpr1005_ext_v2.pdf 73 Tom G3OLB _ Topband Reflector
Topband: 160m Inverted L High SWR
Works OK for me as well! Although mine needs 1600pF and I use little ceramic capacitors rated at 6.3KV, which are readily available from CPC/Farnell at about 10p each. 73 Tom G3OLB <> _ Topband Reflector
Topband: 'Hairpin' matching
The excellent web site for calculating matching network values should have been: http://home.sandiego.edu/~ekim/e194rfs01/jwmatcher/matcher2.html not the one I posted yesterday. 73, Tom G3OLB _ Topband Reflector
Topband: 'Hairpin' matching
Just to add a comment on this thread: I do not use an inductor to match my inverted 'L', just a capacitor from coax centre/bottom of wire to the radial point. Further I do not use big wide space 'toast-rack' Cs, but tiny ceramic ones rated at 6.3KV which will handle very decent amounts of power and are readily available over here. They seem to handle the high currents at the bottom of the quarter wave 'L' quite happily. I measure the impedance at resonance of the antenna without any matching network, then use www.sandiego.edu/~ekim/e194rfs01/jwmatcher2.html to calculate the L-network values needed. Fit the parallel capacitor then lengthen the antenna slightly to bring it back to the required frequency. This provides the inductance necessary for the L-network. Needless to say, your MFJ, or Palstar ZM-30 in my case, antenna analyser will probably give you the wrong sign for the reactive part of the antenna's impedance. This had me going for a long time before I realised the problem! Check this by moving the analyser frequency LF from resonance and the impedance should show -jX (capacitive). Moving the analyser HF from resonance should show inductive reactance (+jX). My inverted 'L' needs 1600pF to give me 50 + j0. I have also made switched L-networks to successfully resonate the same antenna on some other bands. 73 Tom G3OLB _ Topband Reflector
Topband: Fw: Inv-L joy
- Original Message - From: Tom Boucher To: 160 reflector Sent: Tuesday, July 23, 2013 6:30 PM Subject: Inv-L joy What bothers me about putting the actual antenna wire across the tree is that it is then very close and in fact touching the tree. I'm not sure what loss the tree would cause by having it so close. My inverted-L is held 85 ft up in an ash tree by nylon rope. I have a rope and insulator near the bottom which stands it off from the tree in the direction of the top section. I guess mine is 5 or 6 ft away at the top and further at the bottom. Nylon rope is pretty good from an abrasion viewpoint but it will still abrade. My L came down recently after well over a year of backwards and forward over the branches, so now my annual maintenance will include lowering the antenna, shortening the halyard at the top end to allow a fresh section of rope across the branches. Polyester rope is not nearly as abrasion resistant as nylon but looks very similar, so be careful what you are using! 73 Tom G3OLB _ Topband Reflector
Re: Topband: Broadband dipoles
Yes Tom, I was going to mention the polyprop guys as well. Worst stuff you can use. Well remember a 60' mast bent across my neighbours roof as a result of using polyprop guys which had degraded in UV. You get splinters of the stuff in your hands as well! I use polyester (Terylene, Dacron, Trevira) for guys which seems pretty good. Nylon is super strong so I use it for halyards but it does have a fairly high stretch so not ideal for guys. 73 Tom G3OLB W8JI wrote: You mean this part of the SPX data sheet that screams "dummy load"? :-) "Tower guys are made of tough polypropylene rope. The resistive terminations are mounted in protective, ventilated containers." (Polypropylene, unless some special UV inhibited stuff, is terrible in sunlight. Nylon is much better. Polyproplene lasts about a year or two here, while typical nylon lasts a dozen years) Any antenna that says "no tuner required" and covers all frequencies with a low SWR should raise the snake-oil caution flag. _ Topband Reflector
Topband: Broadband dipoles
It's the reference to termination resistors in the SPX data sheet that bothers me. Tom G3OLB K1FZ wrote: http://www.spx.com/en/tci/pd-613t-and-f-broadband-dipole-antennas/> _ Topband Reflector
Topband: Antenna analysers in close proximity to BC station
Thinking again about this, we have missed out a stage. After measuring the tuner output impedance, we need to make a temporary L network which, when terminated with 50 ohms, looks like the antenna. Now put the MFJ on this terminated network and measure it's R +/- jX values which will represent the antenna. 73 Tom G3OLB WO0W wrote: ___ Topband reflector - topband@contesting.com
Topband: Antenna analysers in close proximity to BC station
That's an interesting idea Red and worth a try. 73 Tom G3OLB WO0W wrote: ___ Topband reflector - topband@contesting.com
Topband: Antenna analysers in close proximity to BC station.
A ham friend asked me to design a matching network for his 160 metre end fed quarter wave, so I asked him to provide an impedance reading using his MFJ-259B. I would then use the Berkley site (http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html ) to provide the necessary values for an 'L' network, as I have done many times at my own station. The readings he provided were total nonsense and quite erratic, so we concluded his MFJ-259B was dead. He assured me that he always does a static discharge before connecting the MFJ. So I paid him a visit, taking along my Palstar Antenna analyser thing, which has always performed well at home, and what-do-you-know, the readings on that were also erratic, total nonsense and it behaved in a way I have never seen before. Than someone suggested the problem may be due to a 50Kw BC station on 909 KHz, situated less than 5 miles away, causing both antenna analysers to misbehave. We ended up with a good old-fashioned link coupled parallel tuned circuit with the antenna tapped a few turns up from the ground end. This works fine but he is power limited due to arcing across the tuning capacitor. So we would ideally like to revert to the 'L' network plan, but how to use the antenna analyser in the presence of a high BC station field. Anyone any ideas? 73 Tom G3OLB ___ Topband reflector - topband@contesting.com
Topband: DSL knocks out when on topband
Herb, On the recommendation of John G3PQA, I recently changed my router from a D-Link unit to an ADDON NWAR-3670 which appears to have much better RFI immunity. I'm not getting any dropouts at all now and I do not have an OZ1CTK type filter in line, just some ferrite rings of unknown origin on all the lines in and out. With the old D-Link router the internet connection would drop when running 50W on 160 or 80 even though my antennas are some 3 or 400 feet away from the house and 'phone line. Some of the newer modems are plainly more RFI proof. 73 Tom G3OLB ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: TB Season
G3OIT wrote: Well something just ate my control cable to my remote antenna switch box! Pesky rabbits I think. 73 Tom G3OLB ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Fw: RSGB 1st 1.8 MHz Contest
Tree - delete this please - sent it to the wrong reflector! 73, Tom G3OLB - Original Message - From: Tom Boucher To: 160 reflector Sent: Sunday, February 12, 2012 10:17 AM Subject: RSGB 1st 1.8 MHz Contest Nice to work some old friends last night although G activity seemed low and the last couple of hours were a little painful. 160 QSOs with at least one dupe which was my logging error (sorry Terry!) Nice quiet channel for almost all of the contest and noticeably few keying clicks on the band - perhaps all those FT1000s have now been modified. The K3 once again showed its superb close-in performance and is just great in split Rx or diversity modes. My 85 ft high inverted 'L' is probably not the best transmitting antenna for a UK contest and I would probably do better with a horizontal dipole - next time perhaps. Shack was minus 2 degrees C so as well as the amp, had the fan fire running full belt. Unfortunately tripped the mains breaker part way through so had to reduce power somewhat (the fire, not the amp!) Conditions for DX were not particularly good although the band was open to North America with some weak signals. VE1ZZ called me 5 minutes into the contest - Jack must have been in full daylight at that time. K2ZM, N2FQ and N4RJ were the others with WD5R as my last Q. To the east UA9XF was a good signal but no JAs heard. 73 Tom G3OLB ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: RSGB 1st 1.8 MHz Contest
Nice to work some old friends last night although G activity seemed low and the last couple of hours were a little painful. 160 QSOs with at least one dupe which was my logging error (sorry Terry!) Nice quiet channel for almost all of the contest and noticeably few keying clicks on the band - perhaps all those FT1000s have now been modified. The K3 once again showed its superb close-in performance and is just great in split Rx or diversity modes. My 85 ft high inverted 'L' is probably not the best transmitting antenna for a UK contest and I would probably do better with a horizontal dipole - next time perhaps. Shack was minus 2 degrees C so as well as the amp, had the fan fire running full belt. Unfortunately tripped the mains breaker part way through so had to reduce power somewhat (the fire, not the amp!) Conditions for DX were not particularly good although the band was open to North America with some weak signals. VE1ZZ called me 5 minutes into the contest - Jack must have been in full daylight at that time. K2ZM, N2FQ and N4RJ were the others with WD5R as my last Q. To the east UA9XF was a good signal but no JAs heard. 73 Tom G3OLB ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: 160 Conditions
Who says top-band conditions are in the doldrums? 160 was really singing this morning and signals from the mid-west and west were like I've never heard them. In under an hour at 0500Z, 30 US stations and 17 states worked. Jim N7JW (UT) was knocking the calibrated S meter of my K3 up to 20 over and Randy W6OAR (CA) was over the 9 when we worked. The evening of 6th December was also something else with 26 JAs worked and many more heard in the pile up. Let's hope these conditions continue! 73 & HNY Tom G3OLB ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: 160 metre vertical with 'top loading'
I take your point Yuri, but my simplistic way of looking at the current decreasing along a straight quarter wave of wire is due to the current flow through it's distributed capacitance to ground. Maybe that is wrong and I should go back and look at my transmission line theory. Surely the fact that it is an electrical quarter wave is due to the straight wire being part of one very large coil turn and therefore having an inductance, combined with that distributed capacitance causing resonance at one particular frequency? If that is so, then isn't my theory of the current decay being due to flow through distributed capacitance along it's length still correct? AA7JV said that the argument against current at both ends of the loading coil being the same, is that you cannot have high current and high voltage at the top of the coil because that represents much higher power than you are sticking into the base of the antenna. That's not true because we are talking about VA not Watts, i.e. there is a phase difference between V and I. 73 Tom G3OLB
Topband: 160 metre vertical with 'top loading'
On the eternally recurring argument about current into and out of a loading coil, here is the way my simple mind has always understood it: W8JI is correct in that the current into a perfect inductor must equal the current out of it. It's a piece of coiled wire so where else can the current go? Tom's assumption here is a 'perfect' inductor with no distributed capacitance. K3BU is also correct because he is assuming a practical inductor, with a finite length and distributed capacitance to ground. That's where the missing current is going, through the distributed capacitance to ground and hence lower output current from the top of the inductor into the antenna. Both right, so why the disagreement? 73 Tom G3OLB ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: First attempt at beverage antenna, not working as expected
Just a few comments to Mark WD4ELG: I too have a single short Beverage, about 350' over clay soil and sloping up a hill to the west, fed with about a quarter mile of RG58. It's really too short for top-band, but it does work. Myself and some other Gs have been carrying out daily long path tests with ZL3IX each morning at sunrise for a long while and the beverage has shown itself to be definitely a great advantage over the transmit antenna, an inverted 'L' at 80' and located well away from the house. The transmit antenna itself is not a bad one for receiving as I am in an electrically quiet rural location. Usually signals are slightly better on the Beverage but not hugely. Then occasionally there is a huge difference. An example of this was 2 mornings ago when Greg was peaking an excellent 579 on the short bev, but was barely readable on the 'L'. I'm not at all sure of the propogation mechanism at work here - anyone any ideas? I usually use the two antennas in diversity receive mode on a K3 which gives an added advantage. 73 Tom G3OLB ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
