Re: Topband: New MFJ 259C available
As I looked at things over the years, very few people want VNA's that attach to PC's, and that market is covered anyway. I thought a 259 revision wth direct conversion receivers and a wide frequency range, and a calibrate function, and just basically do what the 259B does now, would have been much better. The RigExpert handheld series of complex impedance analyzers pretty much fit that goal. The AA-54 is in the same price class as the MFJ-259B and has +13 dBm output power. It doesn’t have the frequency range of the 259B but it will accurately cover HF through 6m. At roughly 2x the price, the AA-600 gets you a serious 600 MHz handheld analyzer with OSL calibration and PC graphing connectivity. Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
Thanks, Jim! That's good information, I'll look into it! Thanks! Most of my VNA work in recent years was in the design, tuning and matching of embedded antennas for 900 MHz, 1.4 GHz and 2.5 GHz for electricity, gas and water meters home-area networks and personal security devices. I mostly used a little Smith Chart program called WinSmith 2.0 that was sufficient for my tasks. Those programs you have listed sound interesting, indeed! I'll check 'em out! Many thanks! 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Brown Sent: Wednesday, March 05, 2014 12:25 AM To: topband@contesting.com Subject: Re: Topband: New MFJ 259C available On 3/4/2014 7:04 PM, Charlie Cunningham wrote: I'd also like to be able to apply VNA measurements to some of my HF antennas and I might be willing to take a laptop out there to do that, but I could also just calibrate out the feedline to move the measurement plane out to the antenna and do the measurments from indoors! Would be nice to have the capability! Charlie, Virtually all of the major vector analyzers can write impedance data files in a standard plain text format (called Touchstone) that can be imported by modeling programs like SimSmith. They also allow you to do TDR of the system, so you can subtract out the feedline. From there you can design matching networks. There's a piece on my website that lists several decent analyzers, then shows you to use SimSmith to do these things. SimSmith is FREE, and runs in Java. Dan, AC6LA, has some wonderful Excel spreadsheets that work with this data. One of them will take open circuit and short circuit sweeps for a piece of transmission line and compute Zo, Vf, and attenuation vs frequency. Most of his spreadsheets are free. Dan also sells a spreadsheet that automates EZNEC and, I think, will do optimization. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: ARRL Board Requests Member Comments About Digital Modes
I think Henk's post makes very good sense. As to the limited use of JT9 -- it is a VERY new mode, released only within the past 18 months. Yes, it is superior, and hopefully will be adopted. But that takes time for all to acquire the new software that produces and decodes it, as well as the learning of the software. But I also agree with W4TV, who notes that the difference between JT65 and JT9 matters little with respect to the bandplan and interoperability with other modes. What really matters is that the gear used produce clean signals and that the operators of all modes do so intelligently and with consideration of others. I am FAR more concerned with high power amplifiers cranking out phase noise, splatter, and clicks than I am with the relatively low level of distortion produced by those using digital modes, the vast majority of which are running pretty low power. 73, Jim K9YC On 3/4/2014 11:40 PM, Henk PA5KT wrote: Mike, One of the problems with making band plans is that every region makes its own and then forget how things are arranged in other zones. In EU still a lot of the countries have only 1830-1850 available. To make everybody happy the bandplan has to allow CW, digital and phone in this 20kHz window. Why not using the Region 1 plan as a base? Up to 1838 CW. 1838-1840 CW and narrow band digital with 500Hz bandwidth 1840-1843 digital and other modes. 1843 and higher all modes. Also it would be nice if everybody would use JT9. It is much more efficient, but it is rarely used. Most people stick to JT65. 73 Henk PA5KT _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
On 3/5/2014 7:15 AM, Paul Christensen wrote: +13 dBm may be more than adequate depending on that unit's (AA-54) selectivity. I would like to see it's real world performance in the presence of a strong AMBC field. Paul, There is a VNWA users Yahoo group, which is called VNWA. :) Yahoo groups are easy to join. You could ask about AMBC issues there, and there's a good chance that someone in your area owns one and might bring it to your QTH for a test. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
Hi Paul, Where is a selectivity spec or a description?? 73 Tom - Original Message - From: Paul Christensen w...@arrl.net To: topband topband@contesting.com Sent: Wednesday, March 05, 2014 10:15 AM Subject: Re: Topband: New MFJ 259C available +13 dBm is nothing. That is only 20 milliwatts or 1 volt across 50 ohms if that is at 50 ohms. +13 dBm may be more than adequate depending on that unit's (AA-54) selectivity. I would like to see it's real world performance in the presence of a strong AMBC field. For the CIA/VNA class of analyzers with their high selectivity, that power level is definitely more than sufficient. Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3705/7155 - Release Date: 03/05/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
Hello, In my qth you need at least 30 dBm (1 Watt) for reliable measurements with a broadband detector. The 160m antenna picks up such an amount of signals that with less power you do not get correct results. I allways use a selective methode with bridge, receiver and signal source. Kees, PE5T -- From: Tom W8JI w...@w8ji.com Sent: Wednesday, March 05, 2014 7:08 PM To: Paul Christensen w...@arrl.net; topband topband@contesting.com Subject: Re: Topband: New MFJ 259C available Hi Paul, Where is a selectivity spec or a description?? 73 Tom - Original Message - From: Paul Christensen w...@arrl.net To: topband topband@contesting.com Sent: Wednesday, March 05, 2014 10:15 AM Subject: Re: Topband: New MFJ 259C available +13 dBm is nothing. That is only 20 milliwatts or 1 volt across 50 ohms if that is at 50 ohms. +13 dBm may be more than adequate depending on that unit's (AA-54) selectivity. I would like to see it's real world performance in the presence of a strong AMBC field. For the CIA/VNA class of analyzers with their high selectivity, that power level is definitely more than sufficient. Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3705/7155 - Release Date: 03/05/14 _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
Where is a selectivity spec or a description?? 73 Tom Tom, Apart from the N2PK analyzer, I don't know any published selectivity spec. The detector minimum res. bandwidth of the N2PK unit is 7 Hz and produces +4dBm into 50 ohms. FWIW, RigExpert put together a comparison of analyzers based on measurement topology. For sure, it's a biased piece -- especially when the MFJ product is discussed. So, keep that in mind. http://www.rigexpert.com/index?s=articlesf=aas The plot below shows how well the N2PK analyzer can selectivly ignore a large multi-volt base voltage from three nearby AMBC stations located 2 miles to the south. Two of the AM stations are Non-D in the daytime. One is 15KW, the other is 5KW. Note that the T is resonated to 1420 kHz, right where the stations transmit (look for 1320, 1460, and 1530 kHz). The attached plot shows total RF immunity on the X trace. On the R trace, small blips do show - each representing the local AMBC stations. However, even these can be easily ime-averaged away in the software. http://72.52.250.47/images/N4NN.jpg Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
(look for 1320, 1460, and 1530 kHz). ... and looks like a couple other locals at 1010 and 1060. 73, ... Joe, W4TV On 3/5/2014 2:03 PM, Paul Christensen wrote: Where is a selectivity spec or a description?? 73 Tom Tom, Apart from the N2PK analyzer, I don't know any published selectivity spec. The detector minimum res. bandwidth of the N2PK unit is 7 Hz and produces +4dBm into 50 ohms. FWIW, RigExpert put together a comparison of analyzers based on measurement topology. For sure, it's a biased piece -- especially when the MFJ product is discussed. So, keep that in mind. http://www.rigexpert.com/index?s=articlesf=aas The plot below shows how well the N2PK analyzer can selectivly ignore a large multi-volt base voltage from three nearby AMBC stations located 2 miles to the south. Two of the AM stations are Non-D in the daytime. One is 15KW, the other is 5KW. Note that the T is resonated to 1420 kHz, right where the stations transmit (look for 1320, 1460, and 1530 kHz). The attached plot shows total RF immunity on the X trace. On the R trace, small blips do show - each representing the local AMBC stations. However, even these can be easily ime-averaged away in the software. http://72.52.250.47/images/N4NN.jpg Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
The AIM4170 family is not included in this review? Gregg W6IZT -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Joe Subich, W4TV Sent: Wednesday, March 05, 2014 2:33 PM To: topband@contesting.com Subject: Re: Topband: New MFJ 259C available (look for 1320, 1460, and 1530 kHz). ... and looks like a couple other locals at 1010 and 1060. 73, ... Joe, W4TV On 3/5/2014 2:03 PM, Paul Christensen wrote: Where is a selectivity spec or a description?? 73 Tom Tom, Apart from the N2PK analyzer, I don't know any published selectivity spec. The detector minimum res. bandwidth of the N2PK unit is 7 Hz and produces +4dBm into 50 ohms. FWIW, RigExpert put together a comparison of analyzers based on measurement topology. For sure, it's a biased piece -- especially when the MFJ product is discussed. So, keep that in mind. http://www.rigexpert.com/index?s=articlesf=aas The plot below shows how well the N2PK analyzer can selectivly ignore a large multi-volt base voltage from three nearby AMBC stations located 2 miles to the south. Two of the AM stations are Non-D in the daytime. One is 15KW, the other is 5KW. Note that the T is resonated to 1420 kHz, right where the stations transmit (look for 1320, 1460, and 1530 kHz). The attached plot shows total RF immunity on the X trace. On the R trace, small blips do show - each representing the local AMBC stations. However, even these can be easily ime-averaged away in the software. http://72.52.250.47/images/N4NN.jpg Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
My bad, I see it now. -Original Message- From: Gregg W6IZT [mailto:gregg.w6i...@gmail.com] Sent: Wednesday, March 05, 2014 2:43 PM To: 'topband@contesting.com' Subject: RE: Topband: New MFJ 259C available The AIM4170 family is not included in this review? Gregg W6IZT -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Joe Subich, W4TV Sent: Wednesday, March 05, 2014 2:33 PM To: topband@contesting.com Subject: Re: Topband: New MFJ 259C available (look for 1320, 1460, and 1530 kHz). ... and looks like a couple other locals at 1010 and 1060. 73, ... Joe, W4TV On 3/5/2014 2:03 PM, Paul Christensen wrote: Where is a selectivity spec or a description?? 73 Tom Tom, Apart from the N2PK analyzer, I don't know any published selectivity spec. The detector minimum res. bandwidth of the N2PK unit is 7 Hz and produces +4dBm into 50 ohms. FWIW, RigExpert put together a comparison of analyzers based on measurement topology. For sure, it's a biased piece -- especially when the MFJ product is discussed. So, keep that in mind. http://www.rigexpert.com/index?s=articlesf=aas The plot below shows how well the N2PK analyzer can selectivly ignore a large multi-volt base voltage from three nearby AMBC stations located 2 miles to the south. Two of the AM stations are Non-D in the daytime. One is 15KW, the other is 5KW. Note that the T is resonated to 1420 kHz, right where the stations transmit (look for 1320, 1460, and 1530 kHz). The attached plot shows total RF immunity on the X trace. On the R trace, small blips do show - each representing the local AMBC stations. However, even these can be easily ime-averaged away in the software. http://72.52.250.47/images/N4NN.jpg Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: New MFJ 259C available
Hi Paul, Reading the link, it looks like there are very few analyzers that use receivers, either superheterodyne or direct conversion. The AA-54 is in the class of broadband detectors, which are all sensitive to external RF. http://www.rigexpert.com/index?s=articlesf=aas Scrolling down the page to near the bottom, we find the superheterodyne or direct conversion frequency selective types. This is the mistake I think MFJ made, not doing a selective detector. The single overwhelming problem is external voltage. 73 Tom . - Original Message - From: Paul Christensen w...@arrl.net To: topband topband@contesting.com Sent: Wednesday, March 05, 2014 2:03 PM Subject: Re: Topband: New MFJ 259C available Where is a selectivity spec or a description?? 73 Tom Tom, Apart from the N2PK analyzer, I don't know any published selectivity spec. The detector minimum res. bandwidth of the N2PK unit is 7 Hz and produces +4dBm into 50 ohms. FWIW, RigExpert put together a comparison of analyzers based on measurement topology. For sure, it's a biased piece -- especially when the MFJ product is discussed. So, keep that in mind. http://www.rigexpert.com/index?s=articlesf=aas The plot below shows how well the N2PK analyzer can selectivly ignore a large multi-volt base voltage from three nearby AMBC stations located 2 miles to the south. Two of the AM stations are Non-D in the daytime. One is 15KW, the other is 5KW. Note that the T is resonated to 1420 kHz, right where the stations transmit (look for 1320, 1460, and 1530 kHz). The attached plot shows total RF immunity on the X trace. On the R trace, small blips do show - each representing the local AMBC stations. However, even these can be easily ime-averaged away in the software. http://72.52.250.47/images/N4NN.jpg Paul, W9AC _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3705/7155 - Release Date: 03/05/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
