Re: Circularly-polarized antennas for two-way?
Adding to what Jeff said. For the example of the JPS-SNV-12 the default switching interval is 250 msec so that switching is at a syllabic rate. It can be set as short as 50 msec but then those switch transitions become as annoying as the mobile multipath flutter.? The voter is designed to select the antenna/receiver with lowest noise (FM Mode). If for example the normally vertical polarized signal is received predominantly in horizontal plane via diffraction then the signal received at the horizontal antenna will be stronger than the normal antenna. The multipath flutter will still be present, however the nulls will not be as noisy.?
Multipath flutter sounds quite different at 10 meters as it does at 70 CM or 800 MHz. So if working the lower frequency bands perhaps some experimentation might yield a closer transition to null ratio.?
5.5 SNR Voting and Noise-Only (FM Mode) Voting
Each Site Voter Module uses a Digital Signal Processor to continuously measure the signal and noise levels of the audio input from each receiver site. The signal measurement is made in the 300 to 800 Hz band by a JPS Interoperability Solutions proprietary speech detection and measurement algorithm. The SNV-12 measures not only the energy in this range, but also the amount of syllabic activity. Speech syllables do not consist of continuous energy, but occur at predictable rates and with predictable harmonic content. Noise is measured in the frequency band above 2200 Hz, again using a spectral approach. The Signal to Noise Ratio (SNR) is calculated from the amplitude of calculated signal divided by the amplitude of the noise. The SNR measurement operates from -6 dB to +40 dB. FM systems work best if only the noise
measurement is used for the selection of the best site, while the SNR measurement provides optimal voting performance in more noisy AM and HF systems.
The SNV-12 DSP algorithms are designed to vote speech and noise signals. For this reason the unit¡¯s voting capability cannot be verified by injecting test tones into the receive audio inputs.
In order for a new site to be voted, one SVM must detect a (selectable) better noise level or SNR than the presently voted site, and maintain this difference for a selected voting transition time.
Factory defaults for these settings are 1 dB noise level/SNR difference and a 250 msec voting transition time. This means that if site A is presently voted, site B must maintain a 1 dB noise or SNR advantage over site A for at least 250 msec. in order to be voted in place of site A. Other ¡°voting criteria¡± may be selected to fine-tune system performance. Since the majority of voting systems use FM receivers, the factory default voting method is FM Mode. This voting mode is also recommended whenever low to mid-range tones (below 2.2 kHz) are introduced into the audio spectrum for signaling purposes.
To set the SNV-12 to vote based on SNR (AM/HF mode), a dipswitch must be set on each SVM. Note: All SVMs in a chassis must be set for the same mode; there cannot be a mixture of FM and AM/HF settings on the modules.
5.6 Voting Transition Criteria
The SNV-12 will react and vote immediately when signals appear on a previously inactive system (when the voter changes from all sites squelched to one or more sites unsquelched). An adjustable delay timer sets when a voting transition can occur within a system that is currently active (one site already voted). The voting delay settings are from 50 msec to 5 seconds. The purpose of longer delays is to restrict the number of voting transitions that occur when signal conditions vary rapidly. This voting delay time is set by CPM module switch SW4, a 16-position rotary switch.
In order to be voted over the presently voted site, a new site must also maintain a noise or SNR advantage over the presently voted site for the selected transition time. This signal quality level is adjustable, and set by CPM dipswitches SW2-1, 2, 3. See Section 3 for more information on the noise and SNR differences, and on voting delay settings.
toggle quoted message
Show quoted text
On Mon, Nov 21, 2022 at 11:52 AM, Eric wrote:
Will a voter switch fast/often enough to keep up with the flutter style fading?
?
Eric
WB6TIX
On Mon, Nov 21, 2022, 09:00 RFI-EMI-GUY < rhyolite@...> wrote: Actually, My suggestion is for the second antenna to he a horizontal loop avoiding the hassle and loss related to a CP antenna.
On Sun, Nov 20, 2022 at 09:39 PM, Matt Wagner wrote:
I like RFI-EMI-GUY's recommendation of setting up a pair of receivers fed into a voter -- although building a CP antenna and setting up a receive voter is _two_ projects in one...
?
From what I've seen, Comprod makes a circularly polarized antenna, the 205-70, but doesn't really hype it any:
?
by VE3BYT and VE3KL describes the Skew-Planer antenna, which looks a lot like the cloverleaf antenna seen in 5.8 GHz drones and such. They note difficulty stacking them with anything metallic; it's unclear if this is a unique challenge with this design, though.
?
I think being able to stack a few of them in an array would be helpful, especially since a singular one effectively has -3 dB gain. Could be a fun little antenna project.
Neil you're not the only one! I've tried getting some information from the manufacturers on CPs and got almost nothing.
I do know however that a North Texas group took a DB420 and rotated the dipole elements 90¡ã to horizontal with each pair out of phase at 180¡ã. This meant one dipole on the left was rotated 90¡ã over while the other dipole on the other side was rotated 90¡ã toward the viewer.? All bays were done this way...A pattern check showed an almost perfect horizontal pattern. DB would not acknowledge it because it was modification of their design and they had no intent on trying to prove it one way or the other. If you need more info you could email me direct
?
Chris WB5ITT?
?
?As a Broadcaster, I have asked many of the Commercial? Antenna? manufacturers? If? their Engineers? could develop a prototype antenna for me.? ZERO takers.
?? what I am looking for is a Vertically mounted? Horizontally Polarized? antenna? with at least 9-19 db gain? around 426-440 Mhz? spectrum? for an ATV? repeater
? Yeas? ago? I built a loop ring open Alford slot cage antenna. It worked ok.? Lost the design plans? in a house fire.?? have not been able to Find them since.?? But? looking for a Pipe style? Slotted Dipole array.
? Anyone? have? any? Knowledge? on designing these with specs?? for 426-440??
?
? Neal? KA2CAF
?not sure if there is still an ATV? repeater ? located at Brookdale? Community College? in NJ? on the WBJB? FM? Tower.
?still have My ATV? gear? , and want to Tinker.
?
?
?
On Sunday, November 20, 2022 at 06:33:13 PM EST, Chris Boone < setxtelecom@...> wrote: ?
?
Circular polarization eliminates a lot of mobile flutter due to reflections. Radio broadcast industry normally uses right hand circular polarization on FM and left hand circular polarization on the HD signals. Television is now leaning more toward elliptical with 70% in the horizontal and 30% in the vertical.
If I recall the test that was mentioned in the earlier email was written up in Bill Pasternak's "All you wanted to know about FM and repeaters" book. The CP array that was built used two Cushcraft four poles mounted at 45¡ã off of vertical in each direction. Basically a 4 bay turnstile turned on its side.
?
I thought about building a CP for 6m. The Nicom series in FM broadcast is real easy to duplicate and works rather well. On 2 meters it would be even easier since the size would be smaller.
?
Chris WB5ITT?
?
I've gone down this rabbit hole as well.? There's some ancient documentation out there showcasing some experiment?where a linear and circular antenna at a repeater site were choosable by the users (via DTMF) I guess to get a consensus?which one offered?what the users' observed?as "mo better."? Apparently?the CP won the election.
?
It's said even with vertical mobile antennas, the randomness of reflections of things can cause fluttering and such and CP on the mountain top alleges to help with this.
?
All this in mind, I'm actually in a position to test exactly this here in Virginia in the upcoming year... so I am.? Stay tuned.
?
73
John, kx4o?
On Sun, Nov 20, 2022 at 5:48 PM Matt Wagner < mwaggy@...> wrote:
Howdy,
?
I went down a little bit of a rabbit hole reading about the use of circular polarity in antennas. I'm curious if anyone's experimented with it for repeaters or traditional two-way stuff.
But, while I can read lots of theory about circular polarity in antennas, and see people using it for various purposes, I've found absolutely nothing about people running it on traditional two-way systems. Is this something people have played around with? It sounds like it could be useful, but I can't possibly be the first to have thought of this, so I wonder if it ends up not working out well?
?
?
?
?
?
?
--
The Real RFI-EMI-GUY
? -- The Real RFI-EMI-GUY
|
Re: R1225 Ribbon Cable set
Thanks Mike. I had found them as well but agree that the cost is far beyond it's value. I even tried sending the seller a message to discuss an offer. No interest.?
I'm going to try and source the connectors and just wire up my own.?
Thanks again, Jeremy?
On Mon, Nov 21, 2022, 11:02 AM M M < wa6ilq@...> wrote: There's a set of original cables here:
But the price is, in my opinion, OUTRAGEOUS.??
All they are is 1/10 inch spaced single row ribbon cable.
Mike
|
Re: International crystal manufacturing
What company is this?
There is no continuity to this message.
Glenn
WB4UIV
On 11/21/2022 3:44 AM, Karl Shoemaker
wrote:
It's Monday morning, November 21,? about 12:30am and my outgoing
line (Voip circuit) would not work so I had to use my in coming
line (regular POTS) landline expecting an expensive call on my
next billing.
The call went through using the keystrokes Doug gave.
I asked the person on the phone if they can change frequency on a
channel element, for example Motorola. He said they can not do
that.? They only make and sell the crystal itself.
So, I'm back to "square one".
--
-
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
|
Re: Series-mode surge protection
Agree, the inductance will slow the pulse but does not remove or clamp it.? A gas tube (old and out dated although effective), MOV or MOV/SAD combination device is necessary to clamp the voltage to a reasonably safe level for the connected load.? Please note that the literature at the URL above for this device uses the words:? Conforms to UL Stds 1283 & 1449.? This is not the same as being listed.? This is a common "trick" to deceive and hopefully convince users the product is "listed" but is not the same.? If it was "listed" the manufacturer would be very proud to tell the prospective purchaser that it is.? The probable intent is to deceive the prospective purchaser that the device is "listed".? This also does not state what Edition of UL1449 it "conforms" to.? The statement of zero surge let through voltage is highly improbable when using a recognized surge suppression test and evaluation.? Another example of smoke and magic claims.? Personally, I would not use or recommend this product as a surge suppression device. ? UL Std 1283 relates to EMI filters.? Nothing to do with surge suppression.? This product may be fine for use as a switched outlet strip, EMI filter with very limited surge suppression capability.? Does the user really desire that the load be disconnected when there is an under or over voltage condition? ("catastrophic over/under-voltage shutdown").? Do you visit the site to restore power??
The Eaton URL below offers significant information for those interested in learning about surge suppression devices, practices, installation and evaluation of the device.? I am fully retired and have no affiliation with any manufacturer or vendor.? This information and reference is offered to aid those interested in learning more about surge suppression devices, commonly referenced as SPD or TVSS devices, their installation, testing/evaluation and effectiveness.
73, Bruce , W3YVV
|
Re: International crystal manufacturing
Chuck, I read your suggestion earlier.? In fact the Motorola Maxar does just that; a resistor sits next to the crystal case.
Some sites are off-grid (very low power consumption, like 50 mA on standby) so that's not an option for me.
I have a State-side vendor for *just* the crystal so that's not an issue.? Idealistically, I was trying to find what ICM did for decodes.
Thanks, folks,
--
-
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
|
Re: Need documentation for SS-32M tone encoder
I found out it's the "HB" one.? I can post the sheet if anyone wants it.
--
-
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
|
Re: Series-mode surge protection
Thanks for the links.? Well SurgeX is shy on diagrams or schematics to more fully explain?things though I guess protecting IP trade secrets might be the reason if not for the mentioning of this technique being patented.? If the patent exists, there's nothing to fear from publishing more detail than the ever so slightly?shallow verbal description.
I recall some of the Polyphaser AC protectors used series methods as well.
Perhaps it's time to buy one and dissect?it for the actual design.? Who knows... maybe it actually does what they say.
John
Here is a link to the SurgeX SX-1115-RT?datasheet:
According to the datasheet:
- The device is UL 1449 listed.
- The surge let-through voltage is zero volts.
This web page describes the theory of operation:
"...a reactor with two opposing air core inductors to slow surge current down to a trickle. Any residual energy leaving the inductors is eliminated by a clamping board. It removes all surge energy, allows zero let-through voltage to reach connected equipment, the ground or building wiring, and produces no common-mode disturbances. Its zero let-through technology stops all surge energy, up to 6,000 volts, without producing harmful ground contamination."
|
Re: Circularly-polarized antennas for two-way?
Matt, I used a circularly polarized antenna on the WA6TDD repeater back in the 70's and early 80's. The antenna was a single bay antenna made specifically for the repeater by the JAMPRO antenna Company as a test for the 2-way world. It even has de-icers!? If you're familiar with the JAMPRO Penetrator antenna, this was the same antenna with the exception that it was center mounted; the mast was straight down below the white insulator at the feed point. This replaced a (linear) Phelps Dodge 4.8 dB gain Super-Duper Storm Master antenna.? The gain went from approximately +4.8 db to - 3 dB.? The ERP went from 100 watts to approximately 13 watts. Just to clarify, the repeater transmit was now circular and all of the users were linear; none of the users were circular.? The difference in coverage of transmit was amazing. For example: at the time I worked in a 33 story building with 6 levels of underground parking. With the linear antenna I was able to copy the repeater with its 100 watts ERP about 25 feet into the parking entrance and that was it. With the circular antenna on the repeater and a 19" spike on the top of my car I was able to copy the repeater solid down to the 2nd level and hear it spotty down to the 5th level.? At some places on the 5th level I could find spots that were almost full quieting.? People that listened to the repeater with radios like the old Patrolmen type receivers claimed that they no longer had to place their receivers near the window and fiddle with the antenna, they could now take the radio anywhere in their homes and hear the repeater with no problems. It was solid through areas like the Santa Ana Canyon and Sepulveda Pass. What was rather humorous and showed a lack of understanding by some users, who were upset that the repeater was no longer ""60 over S9," it was now only "20 over S9." The fact that it had better coverage and penetration was not the point! Now for the bad news.? It didn't hear very well.? It simply had too small an aperture. While stations could hear the repeater better than ever, and had been solid into the repeater with the 4.8 dB gain linear antenna, they? were now not so solid.? Handhelds that had no problems now had problems.? We eventually went back to the Phelps Dodge Linear antenna. What did we learn?? We learned that circular transmit to linear receive is a plus.? Yes, circular to circular is best, but not very practical. Think about putting a circularly polarized antenna on your car or handheld radio. If you have a circularly polarized antenna that truly commutates, it will be optimally coupled to a linear receive antenna even when the polarization of the signal as received is "spun" due to bounces and other propagation anomalies. It really works! You can read more about this at ? download and read the pdf file. Hopefully attached is a picture of the Antenna that JAMPRO build for the WA6TDD Repeater. Burt, K6OQK 
|
Re: International crystal manufacturing
AT&T had analog MSF5000 repeaters on the microwave sites that had a 4 wire circuit going back to the regional #4ESS
that provided a switch based method of interconnection between repeaters.
When microwave had problems they used their radios and had a private two-digit dialing plan to get to the destination
repeater. I saw DLR/CLR (design layout record/circuit layout record) that was left on a couple of sites that showed
everything including the dialing plan.
In a way, this could be described as a VERY EXPENSIVE predecessor to IRLP. MCI had a similar nationwide system with UHF repeaters but I don't know if or how it was tied into the switched network. Anyone from MCI on this list? Our company's warehouse is a former MCI microwave hub - I'd love to pick your brain about some of the equipment and facilities we inherited. I grew up in a telco family as well. Some of my earliest memories include visiting CO's in northeastern and central Pennsylvania with my dad. --- Jeff WN3A -- This email has been checked for viruses by Avast antivirus software. www.avast.com
|
Re: Circularly-polarized antennas for two-way?
Will a voter switch fast/often enough to keep up with the flutter style fading? Good question. Simple answer: no, generally speaking, a regular SNR voter and two separate cross-polarized antennas won't be effective in combatting mobile flutter. The rate of mobile flutter is primarily a function of two things; the relative velocity of the stations (in the case of a repeater, only the mobile is moving), and the wavelength (the shorter the wavelength, the faster the flutter for a given velocity). A voting comparator designed to specifically deal with mobile multipath flutter could be designed, and back in the AMPS cellular days, such designs were effective, but the voting was not based on comparing relative SNR's in the audio domain like a typical two-way voter does. To others that have commented: at any instant of time, there is no guarantee that that, at any instant in time or space, multipath experienced at the receiver is being caused by cross-polarization. That is, don't assume that simply having two linear cross-polarized antennas, or even a single circular polarized antenna, is going to magically cure multipath. CP helps to address polarization skew caused by reflections, but the reflections are still there - there can, and will, still be destructive cancellation that can't be avoided regardless of whether the receiving antennas is linear or cpol. And of course, whenever a CP signal is reflected, its polarization sense is inverted, so a mobile CP antenna absolutely does not help deal with multipath if the repeater is also CP. The US is one of the countries that regularly uses CP on FM broadcast, and to a lesser extent on TV, but it's certainly not a worldwide standard. Many countries, including most of Eu, use linear polarization. There have been a lot of studies done on the subject of reception of Vpol vs Hpol vs Cpol vs slant-pol transmitted signals using linearly-polarized receiving antennas, often with conflicting results. Bottom line: CP can help in some situations, but it's not a magic cure. I'm not trying to dissuade anyone from experimentation, just have reasonable expectations on what you'll achieve. --- Jeff WN3A -- This email has been checked for viruses by Avast antivirus software. www.avast.com
|
Re: MIII Programming Software
There is absolutely nothing on repeater-builder on programming the Mastr III station.
Anybody want to write something?
Mike WA6ILQ
|
Re: R1225 Ribbon Cable set
There's a set of original cables here:
But the price is, in my opinion, OUTRAGEOUS.??
All they are is 1/10 inch spaced single row ribbon cable.
Mike
|
Re: MIII Programming Software
M III ver 17 was the last version we had also. The RPM software we got IS tied to computer by a key. The only way around we found was to clone the hard drives, which meant you had to have the same exact computers.
|
Re: Circularly-polarized antennas for two-way?
Will a voter switch fast/often enough to keep up with the flutter style fading?
Eric WB6TIX
On Mon, Nov 21, 2022, 09:00 RFI-EMI-GUY < rhyolite@...> wrote: Actually, My suggestion is for the second antenna to he a horizontal loop avoiding the hassle and loss related to a CP antenna.
On Sun, Nov 20, 2022 at 09:39 PM, Matt Wagner wrote:
I like RFI-EMI-GUY's recommendation of setting up a pair of receivers fed into a voter -- although building a CP antenna and setting up a receive voter is _two_ projects in one...
?
From what I've seen, Comprod makes a circularly polarized antenna, the 205-70, but doesn't really hype it any:
?
by VE3BYT and VE3KL describes the Skew-Planer antenna, which looks a lot like the cloverleaf antenna seen in 5.8 GHz drones and such. They note difficulty stacking them with anything metallic; it's unclear if this is a unique challenge with this design, though.
?
I think being able to stack a few of them in an array would be helpful, especially since a singular one effectively has -3 dB gain. Could be a fun little antenna project.
Neil you're not the only one! I've tried getting some information from the manufacturers on CPs and got almost nothing.
I do know however that a North Texas group took a DB420 and rotated the dipole elements 90¡ã to horizontal with each pair out of phase at 180¡ã. This meant one dipole on the left was rotated 90¡ã over while the other dipole on the other side was rotated 90¡ã toward the viewer.? All bays were done this way...A pattern check showed an almost perfect horizontal pattern. DB would not acknowledge it because it was modification of their design and they had no intent on trying to prove it one way or the other. If you need more info you could email me direct
?
Chris WB5ITT?
?
?As a Broadcaster, I have asked many of the Commercial? Antenna? manufacturers? If? their Engineers? could develop a prototype antenna for me.? ZERO takers.
?? what I am looking for is a Vertically mounted? Horizontally Polarized? antenna? with at least 9-19 db gain? around 426-440 Mhz? spectrum? for an ATV? repeater
? Yeas? ago? I built a loop ring open Alford slot cage antenna. It worked ok.? Lost the design plans? in a house fire.?? have not been able to Find them since.?? But? looking for a Pipe style? Slotted Dipole array.
? Anyone? have? any? Knowledge? on designing these with specs?? for 426-440??
?
? Neal? KA2CAF
?not sure if there is still an ATV? repeater ? located at Brookdale? Community College? in NJ? on the WBJB? FM? Tower.
?still have My ATV? gear? , and want to Tinker.
?
?
?
On Sunday, November 20, 2022 at 06:33:13 PM EST, Chris Boone < setxtelecom@...> wrote: ?
?
Circular polarization eliminates a lot of mobile flutter due to reflections. Radio broadcast industry normally uses right hand circular polarization on FM and left hand circular polarization on the HD signals. Television is now leaning more toward elliptical with 70% in the horizontal and 30% in the vertical.
If I recall the test that was mentioned in the earlier email was written up in Bill Pasternak's "All you wanted to know about FM and repeaters" book. The CP array that was built used two Cushcraft four poles mounted at 45¡ã off of vertical in each direction. Basically a 4 bay turnstile turned on its side.
?
I thought about building a CP for 6m. The Nicom series in FM broadcast is real easy to duplicate and works rather well. On 2 meters it would be even easier since the size would be smaller.
?
Chris WB5ITT?
?
I've gone down this rabbit hole as well.? There's some ancient documentation out there showcasing some experiment?where a linear and circular antenna at a repeater site were choosable by the users (via DTMF) I guess to get a consensus?which one offered?what the users' observed?as "mo better."? Apparently?the CP won the election.
?
It's said even with vertical mobile antennas, the randomness of reflections of things can cause fluttering and such and CP on the mountain top alleges to help with this.
?
All this in mind, I'm actually in a position to test exactly this here in Virginia in the upcoming year... so I am.? Stay tuned.
?
73
John, kx4o?
On Sun, Nov 20, 2022 at 5:48 PM Matt Wagner < mwaggy@...> wrote:
Howdy,
?
I went down a little bit of a rabbit hole reading about the use of circular polarity in antennas. I'm curious if anyone's experimented with it for repeaters or traditional two-way stuff.
But, while I can read lots of theory about circular polarity in antennas, and see people using it for various purposes, I've found absolutely nothing about people running it on traditional two-way systems. Is this something people have played around with? It sounds like it could be useful, but I can't possibly be the first to have thought of this, so I wonder if it ends up not working out well?
?
?
?
?
?
?
--
The Real RFI-EMI-GUY
|
Re: MIII Programming Software
The last version of the Mastr IIe/III program, which I believe is V17, is what is needed, and it is not tied to a PC. It looks DOS based, but it runs fine in XP at least.
ProGrammer is what is tied to a PC, and I never used it for MIII's. I don't even remember seeing the option for that to be supported.
toggle quoted message
Show quoted text
On 11/21/2022 11:38 AM, J Donovan via groups.io wrote: For the newer stations (stripes) you will need the newer win based software package that is tied to you computer. I don't know if Harris still supports these stations as we bought everytning we needed in 2012. It required an online verification or an activation key for each computer (seat)? by email.
Having said that and using both packages from my experience on stations we purchased in 2012 you can program the newer stations with the older DOS based software (PIA), but using the newer software on the older non striped version will brick them.
_._,_._,_
|
Re: MIII Programming Software
Having said that and using both packages from my experience on stations we purchased in 2012
you can program the newer stations with the older DOS based software (PIA), but using the newer
software on the older non striped version will brick them. That has been my experience as well, at least for analog stations. You may need the Windows software to program a P25 station which has a DSP card needed for P25; I don't have any P25 stations so that's just an educated guess... --- Jeff WN3A -- This email has been checked for viruses by Avast antivirus software. www.avast.com
|
Re: MIII Programming Software
For the newer stations (stripes) you will need the newer win based software package that is tied to you computer. I don't know if Harris still supports these stations as we bought everytning we needed in 2012. It required an online verification or an activation key for each computer (seat)? by email.
Having said that and using both packages from my experience on stations we purchased in 2012 you can program the newer stations with the older DOS based software (PIA), but using the newer software on the older non striped version will brick them.
|
Re: Circularly-polarized antennas for two-way?
Actually, My suggestion is for the second antenna to he a horizontal loop avoiding the hassle and loss related to a CP antenna.
toggle quoted message
Show quoted text
On Sun, Nov 20, 2022 at 09:39 PM, Matt Wagner wrote:
I like RFI-EMI-GUY's recommendation of setting up a pair of receivers fed into a voter -- although building a CP antenna and setting up a receive voter is _two_ projects in one...
?
From what I've seen, Comprod makes a circularly polarized antenna, the 205-70, but doesn't really hype it any:
?
by VE3BYT and VE3KL describes the Skew-Planer antenna, which looks a lot like the cloverleaf antenna seen in 5.8 GHz drones and such. They note difficulty stacking them with anything metallic; it's unclear if this is a unique challenge with this design, though.
?
I think being able to stack a few of them in an array would be helpful, especially since a singular one effectively has -3 dB gain. Could be a fun little antenna project.
Neil you're not the only one! I've tried getting some information from the manufacturers on CPs and got almost nothing.
I do know however that a North Texas group took a DB420 and rotated the dipole elements 90¡ã to horizontal with each pair out of phase at 180¡ã. This meant one dipole on the left was rotated 90¡ã over while the other dipole on the other side was rotated 90¡ã toward the viewer.? All bays were done this way...A pattern check showed an almost perfect horizontal pattern. DB would not acknowledge it because it was modification of their design and they had no intent on trying to prove it one way or the other. If you need more info you could email me direct
?
Chris WB5ITT?
?
?As a Broadcaster, I have asked many of the Commercial? Antenna? manufacturers? If? their Engineers? could develop a prototype antenna for me.? ZERO takers.
?? what I am looking for is a Vertically mounted? Horizontally Polarized? antenna? with at least 9-19 db gain? around 426-440 Mhz? spectrum? for an ATV? repeater
? Yeas? ago? I built a loop ring open Alford slot cage antenna. It worked ok.? Lost the design plans? in a house fire.?? have not been able to Find them since.?? But? looking for a Pipe style? Slotted Dipole array.
? Anyone? have? any? Knowledge? on designing these with specs?? for 426-440??
?
? Neal? KA2CAF
?not sure if there is still an ATV? repeater ? located at Brookdale? Community College? in NJ? on the WBJB? FM? Tower.
?still have My ATV? gear? , and want to Tinker.
?
?
?
On Sunday, November 20, 2022 at 06:33:13 PM EST, Chris Boone < setxtelecom@...> wrote: ?
?
Circular polarization eliminates a lot of mobile flutter due to reflections. Radio broadcast industry normally uses right hand circular polarization on FM and left hand circular polarization on the HD signals. Television is now leaning more toward elliptical with 70% in the horizontal and 30% in the vertical.
If I recall the test that was mentioned in the earlier email was written up in Bill Pasternak's "All you wanted to know about FM and repeaters" book. The CP array that was built used two Cushcraft four poles mounted at 45¡ã off of vertical in each direction. Basically a 4 bay turnstile turned on its side.
?
I thought about building a CP for 6m. The Nicom series in FM broadcast is real easy to duplicate and works rather well. On 2 meters it would be even easier since the size would be smaller.
?
Chris WB5ITT?
?
I've gone down this rabbit hole as well.? There's some ancient documentation out there showcasing some experiment?where a linear and circular antenna at a repeater site were choosable by the users (via DTMF) I guess to get a consensus?which one offered?what the users' observed?as "mo better."? Apparently?the CP won the election.
?
It's said even with vertical mobile antennas, the randomness of reflections of things can cause fluttering and such and CP on the mountain top alleges to help with this.
?
All this in mind, I'm actually in a position to test exactly this here in Virginia in the upcoming year... so I am.? Stay tuned.
?
73
John, kx4o?
On Sun, Nov 20, 2022 at 5:48 PM Matt Wagner < mwaggy@...> wrote:
Howdy,
?
I went down a little bit of a rabbit hole reading about the use of circular polarity in antennas. I'm curious if anyone's experimented with it for repeaters or traditional two-way stuff.
But, while I can read lots of theory about circular polarity in antennas, and see people using it for various purposes, I've found absolutely nothing about people running it on traditional two-way systems. Is this something people have played around with? It sounds like it could be useful, but I can't possibly be the first to have thought of this, so I wonder if it ends up not working out well?
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? -- The Real RFI-EMI-GUY
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I have excess to my needs a single port RLC Club in rack mount case.. bought it planning to add the deluxe II board but decided not to since I have already too many RLCs. Asking $550 for it plus shipping
Chris WB5ITT
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Re: Series-mode surge protection
Here is a link to the SurgeX SX-1115-RT?datasheet:
According to the datasheet:
- The device is UL 1449 listed.
- The surge let-through voltage is zero volts.
This web page describes the theory of operation:
"...a reactor with two opposing air core inductors to slow surge current down to a trickle. Any residual energy leaving the inductors is eliminated by a clamping board. It removes all surge energy, allows zero let-through voltage to reach connected equipment, the ground or building wiring, and produces no common-mode disturbances. Its zero let-through technology stops all surge energy, up to 6,000 volts, without producing harmful ground contamination."
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RFI-EMI-GUY
Karl Shoemaker
Burt K6OQK
Chris Boone WB5ITT