Re: Topband: Broad band antenna approach for 160 Contesting
Rick at al, My comments in line On 2/28/2021 12:31, Richard (Rick) Karlquist wrote: On 2/28/2021 7:40 AM, Grant Saviers wrote: The nice thing about switched serial caps (if same values) for tuning upwards from a low resonance is the voltages are all the same. Plus caps and appropriate relays are cheap, easy, and small. Rick, I think you might have suggested this to me, and my implementation was published in QEX May/June 2019. Grant KZ1W Grant, Dave etc: I hadn't seen this article: the DVD was still shrink wrapped :-) Anyway, nice write up, it's similar to what I did, so maybe I suggested it. A couple of discussion points (not criticisms): 1. I use binary weighted cap values. In the article you say you going to do that but a comment on this reflector changed your mind to equal values. You mention in your posting today that this is nice because all the voltages are the same. Is there any other reason for this decision? The advantage of the binary weighting of course is that only two caps and only two relays are needed for four segments (or 3 and 3 for 8 segments). For my T, 85ft up and 2x 33ft arms, 8x 125ft 10ft up radials, resonant at 1825+/-, the 40 KHz almost equal steps modeled with one value cap 4000pf, so the series values were 4000, 2000, 1666, and short. Works per the modeling. That yielded the swr curves shown. There is an error in the schematic as wire numbers were mixed up and ground doesn't connect control to relay box properly. Other ones don't matter since all caps are the same value. 2. Figure 7 shows 6 relays to get "all decodes"? Perhaps this got messed up in Newington. Can you explain it better? The control box PCB was a general purpose diode decoder, up to 6 outputs. only 3 used in this application. 3. Figure 8 shows your 50 ohm t0 25 ohm matching transformer. The text credits K9YC and then goes on to say it is a transformer, a balun, and a common mode choke, all in one. I know K9YC very well and he correctly rails against the misapplication of the word "balun". Maybe more QRM from Newington? Choke and TLT/unun are separate. Choke about 5k ohms RG142 on FT240-31, TLT 50:22 Balun Designs. Pre K9YC designs with the 4" cores. Anyway, if you were going from 50 ohms to 12.5 ohms, this loose talk could almost be true. But AFAIK, going from 50 ohms to 22.2 ohms (3:2 turns ratio) is simply an unun, which is an autotransformer. At least that's what I'm doing. It could never be confused with a transformer, balun or common mode choke. 4. I like the Schrack relays. I see that DigiKey still has these available, but they identify them as "TE Connectivity Potter & Brumfield" but they also say "Series RZ, SCHRACK." I may use those going forward in place of the ones I used before. You mentioned the CDE mica caps I used, and then said you used cheap Ukrainian ones. Do you by any chance have a pointer to them on ebay? I realize that 4 years is a long time in ebay years, so maybe not. I looked on ebay for some more of the Tx caps a few months ago - no luck. BTW, an additional advantage of using capacitors instead of a tapped inductor is that the inductor will lose a lot of Q if a metal enclosure is used, unless it is huge. A plastic enclosure is clumsy and self destructs in sunlight. Plus sub one ohm inductors are pretty hard to make vs the Q of silver micas. Finally: have you gotten a lot of response to the article, especially in terms of people actually building it? Maybe I need to jump on the frequency agility bandwagon, if there is a critical mass of other stations to work who are on board. One builder who pointed out the wire number error. Besides agility for SSB, I built it to operate in the now defunct JA band plan. Keep the good ideas coming guys! 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Broad band antenna approach for 160 Contesting
I have been using a shunt fed 45G tower for many years with around 50 radials. It is top loaded with a mono stack from 80 to 10 meters. It works extremely well on 160 using an Omega match. There is a 1000 pfd vacuum variable in series with a motor driven 1000 pfd vacuum variable to ground. The motor is a reversible 1 RPM, 12 VDC motor that is tuned remotely from the shack. The SWR is always 1.3/1 or better. The tower is 100 feet high. I can usually work anything I can hear. The receiving antennas are a Hi-Z 8, Hi-Z 2, NW BOG, and a Waller FLAG on a 40 ft boom at 93 feet. The FLAG shines on the long path. 73, John, W4NU K4JAG (1959 to 1998) Atlanta Sent from my iPhone > On Feb 28, 2021, at 10:41 AM, Grant Saviers wrote: > > The nice thing about switched serial caps (if same values) for tuning > upwards from a low resonance is the voltages are all the same. Plus caps and > appropriate relays are cheap, easy, and small. > > Rick, I think you might have suggested this to me, and my implementation was > published in QEX May/June 2019. > > Grant KZ1W > >> On 2/28/2021 07:10, Richard (Rick) Karlquist wrote: >>> On 2/27/2021 2:23 PM, Artek Manuals wrote: >>> Rick et all >>> >> he feed, The taps are relay selected . Taps selected for a dip >>> at 1816, 1840 , 1860, 1880, 1900 and 1920. SWR 1.3:1 from 1.8 to 19.5 which >>> the my KPA1500 and Alpha 9500 both love. >>> >>> Dave >>> NR1DX >>> manu...@artekmanuals.com >>> >> Thanks for posting this suggestion. Perfectly reasonable design. >> I use an alternative design using switched mica capacitors. >> I also use a 2.25:1 matching transformer, but the "windings" >> are implemented using coax. Not sure if Sevick does this. >> 73 >> Rick N6RK >> _ >> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector > _ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Broad band antenna approach for 160 Contesting
It would be nice to read your article but ARRL's absurd policy of not allowing it keeps me from seeing it. Crazy that I can read the current issue online, but cannot see back issues. Wes N7WS On 2/28/2021 8:40 AM, Grant Saviers wrote: The nice thing about switched serial caps (if same values) for tuning upwards from a low resonance is the voltages are all the same. Plus caps and appropriate relays are cheap, easy, and small. Rick, I think you might have suggested this to me, and my implementation was published in QEX May/June 2019. Grant KZ1W _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Broad band antenna approach for 160 Contesting
On 2/28/2021 7:40 AM, Grant Saviers wrote: The nice thing about switched serial caps (if same values) for tuning upwards from a low resonance is the voltages are all the same. Plus caps and appropriate relays are cheap, easy, and small. Rick, I think you might have suggested this to me, and my implementation was published in QEX May/June 2019. Grant KZ1W Grant, Dave etc: I hadn't seen this article: the DVD was still shrink wrapped :-) Anyway, nice write up, it's similar to what I did, so maybe I suggested it. A couple of discussion points (not criticisms): 1. I use binary weighted cap values. In the article you say you going to do that but a comment on this reflector changed your mind to equal values. You mention in your posting today that this is nice because all the voltages are the same. Is there any other reason for this decision? The advantage of the binary weighting of course is that only two caps and only two relays are needed for four segments (or 3 and 3 for 8 segments). 2. Figure 7 shows 6 relays to get "all decodes"? Perhaps this got messed up in Newington. Can you explain it better? 3. Figure 8 shows your 50 ohm t0 25 ohm matching transformer. The text credits K9YC and then goes on to say it is a transformer, a balun, and a common mode choke, all in one. I know K9YC very well and he correctly rails against the misapplication of the word "balun". Maybe more QRM from Newington? Anyway, if you were going from 50 ohms to 12.5 ohms, this loose talk could almost be true. But AFAIK, going from 50 ohms to 22.2 ohms (3:2 turns ratio) is simply an unun, which is an autotransformer. At least that's what I'm doing. It could never be confused with a transformer, balun or common mode choke. 4. I like the Schrack relays. I see that DigiKey still has these available, but they identify them as "TE Connectivity Potter & Brumfield" but they also say "Series RZ, SCHRACK." I may use those going forward in place of the ones I used before. You mentioned the CDE mica caps I used, and then said you used cheap Ukrainian ones. Do you by any chance have a pointer to them on ebay? I realize that 4 years is a long time in ebay years, so maybe not. BTW, an additional advantage of using capacitors instead of a tapped inductor is that the inductor will lose a lot of Q if a metal enclosure is used, unless it is huge. A plastic enclosure is clumsy and self destructs in sunlight. Finally: have you gotten a lot of response to the article, especially in terms of people actually building it? Maybe I need to jump on the frequency agility bandwagon, if there is a critical mass of other stations to work who are on board. Keep the good ideas coming guys! 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Broad band antenna approach for 160 Contesting
The nice thing about switched serial caps (if same values) for tuning upwards from a low resonance is the voltages are all the same. Plus caps and appropriate relays are cheap, easy, and small. Rick, I think you might have suggested this to me, and my implementation was published in QEX May/June 2019. Grant KZ1W On 2/28/2021 07:10, Richard (Rick) Karlquist wrote: On 2/27/2021 2:23 PM, Artek Manuals wrote: Rick et all he feed, The taps are relay selected . Taps selected for a dip at 1816, 1840 , 1860, 1880, 1900 and 1920. SWR 1.3:1 from 1.8 to 19.5 which the my KPA1500 and Alpha 9500 both love. Dave NR1DX manu...@artekmanuals.com Thanks for posting this suggestion. Perfectly reasonable design. I use an alternative design using switched mica capacitors. I also use a 2.25:1 matching transformer, but the "windings" are implemented using coax. Not sure if Sevick does this. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: Broad band antenna approach for 160 Contesting
On 2/27/2021 2:23 PM, Artek Manuals wrote: Rick et all he feed, The taps are relay selected . Taps selected for a dip at 1816, 1840 , 1860, 1880, 1900 and 1920. SWR 1.3:1 from 1.8 to 19.5 which the my KPA1500 and Alpha 9500 both love. Dave NR1DX manu...@artekmanuals.com Thanks for posting this suggestion. Perfectly reasonable design. I use an alternative design using switched mica capacitors. I also use a 2.25:1 matching transformer, but the "windings" are implemented using coax. Not sure if Sevick does this. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: Broad band antenna approach for 160 Contesting
Rick et all I have changed the Subject line rather than further hijack Tree's original thread I have a "T" Radiator 60' high with flat top of the T, 80' long. Next 4 elevated non resonant 90' radials at 6ft.This gets me to ~22.5 ohms, 2.25:1 matching transformer out of Sevick to go to 50ohms . I then tune the system to resonance with a tapped inductor in series with the radial side of the feed, The taps are relay selected . Taps selected for a dip at 1816, 1840 , 1860, 1880, 1900 and 1920. SWR 1.3:1 from 1.8 to 19.5 which the my KPA1500 and Alpha 9500 both love. Dave NR1DX manu...@artekmanuals.com On 2/27/2021 3:23 PM, Richard (Rick) Karlquist wrote: On 2/27/2021 11:01 AM, Tree wrote: My general comments about the contest. Back about 15 years ago - it seemed like there was plenty of activity above 1900. AA1K spent most of the contest in 1999 kHz. Maybe it was conditions - but it seemed to be a lot less going on this year above 1.9 MHz. I had I thought about retuning my TX vertical somewhat higher temporarily just for this contest, but I was thinking that many stations would not have the capability to go above 1.9 MHz, so CQ'ing up there would have limited success. Without changing from my "normal" CW setting, I can get away with going up to almost 1.9 MHz before the Alpha 9500 complains too much. What is really needed is a remote switched tuning network that would divide the band into eight 25 kHz segments. Then I could S the high frequency stations on a demand basis. It is on my "someday" list of things to build. I already have built one for 80/75 meters with 8 segments, so the design is in my head. Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector -- Dave manu...@artekmanuals.com www.ArtekManuals.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
