Re: [Elecraft] low pass filters
OTA TV is growing rapidly which is why cable companies are hurting. I’ve been exclusively OTA for over 10 years. Also, with the repack a number of stations are being moved back to VHF. Sent from my iPad On Feb 18, 2019, at 11:41 PM, K9MA wrote: >> On Sun, Feb 17, 2019 at 4:26 PM Don Wilhelm wrote: >> >> >> Low pass filters come from a past era when the FCC requirements were not >> as stringent and TVs responded to those higher order harmonics from >> amateur transmitters. That is no longer the case. > > Here, Don is talking about external low pass filters intended to suppress VHF > harmonics. If you live in an area where TV signals are weak, they may still > be necessary. Of course, hardly anyone receives their TV service that way any > more, and most TV stations have moved to the UHF bands, anyway. > > The low pass filters in solid state radios and amplifiers are necessary > because their outputs are untuned, and the nonlinearity of transistors > generates lots of harmonics, including low order ones. In the days of vacuum > tubes, the pi network served as an effective filter. The popular pi-L was > even better. > > It might be interesting, during a major contest, to listen on the second > harmonic, say around 14.120 when there's a lot of activity on 40. Many are > using solid state amplifiers now, and even 43 dB down may be audible. I've > never positively identified one, but a lot of stations don't come back to me > for other reasons, so it would be hard to tell. > > > 73, > > Scott K9MA > > -- > Scott K9MA > > k...@sdellington.us > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to w...@w2xj.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] low pass filters
On Sun, Feb 17, 2019 at 4:26 PM Don Wilhelm wrote: Low pass filters come from a past era when the FCC requirements were not as stringent and TVs responded to those higher order harmonics from amateur transmitters. That is no longer the case. Here, Don is talking about external low pass filters intended to suppress VHF harmonics. If you live in an area where TV signals are weak, they may still be necessary. Of course, hardly anyone receives their TV service that way any more, and most TV stations have moved to the UHF bands, anyway. The low pass filters in solid state radios and amplifiers are necessary because their outputs are untuned, and the nonlinearity of transistors generates lots of harmonics, including low order ones. In the days of vacuum tubes, the pi network served as an effective filter. The popular pi-L was even better. It might be interesting, during a major contest, to listen on the second harmonic, say around 14.120 when there's a lot of activity on 40. Many are using solid state amplifiers now, and even 43 dB down may be audible. I've never positively identified one, but a lot of stations don't come back to me for other reasons, so it would be hard to tell. 73, Scott K9MA -- Scott K9MA k...@sdellington.us __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Inrad W1 Headset and K3
Hi Jim I bought several MC500, I am happy with them, but not good isolation when doing multi on SSB And the foam is shelled very quickly 73, Jorge Enviado desde mi iPhone El 18 feb. 2019, a la(s) 19:56, Jim Brown escribió: > On 2/18/2019 5:02 PM, Dick Dievendorff wrote: >> I used mine this weekend, I am very happy with them. The headset has a 1/4 >> stereo phone plug that is quite robust when compared with a 3.5 mm plug and >> an adapter. The cable is long and seems sturdy. Very comfortable over the >> ear phones with good isolation. > > If I had $195 (headset plus mic plug adapter) to spend and needed a good > boom-mic headset, I'd buy a CM500 and a couple of bottles of a REALLY nice > single malt. The only reason I can think of to spend that kind of money is if > the headphones have REALLY great isolation from room noise, and then only > room noise was a problem for me (like in a SSB multi-op contest station). And > I'd do the A/B comparison before plunking down the bucks. > > There's BS in the product description too -- "1 1/2 feet coiled cord for RF > suppression" is nonsense. If anything the added length makes it a better > receiving antenna for radios with RF problems! And there is zero magic to 600 > ohms -- we haven't matched impedances in audio for nearly 50 years! It's > simply a low impedance mic, and virtually all mics used in ham radio have > been low impedance for at least that long. > > I've been using a CM500 for about ten years, and the only thing that breaks > is the cable, because I'm really a klutz with headsets. It's not replaceable, > and I don't see a note that the cable in this one is either. If I'm not > mistaken, the excellent Sennheiser headset DOES have a replaceable cable. > > 73, Jim K9YC > > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to cx6vm.jo...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Inrad W1 Headset and K3
On 2/18/2019 5:02 PM, Dick Dievendorff wrote: I used mine this weekend, I am very happy with them. The headset has a 1/4 stereo phone plug that is quite robust when compared with a 3.5 mm plug and an adapter. The cable is long and seems sturdy. Very comfortable over the ear phones with good isolation. If I had $195 (headset plus mic plug adapter) to spend and needed a good boom-mic headset, I'd buy a CM500 and a couple of bottles of a REALLY nice single malt. The only reason I can think of to spend that kind of money is if the headphones have REALLY great isolation from room noise, and then only room noise was a problem for me (like in a SSB multi-op contest station). And I'd do the A/B comparison before plunking down the bucks. There's BS in the product description too -- "1 1/2 feet coiled cord for RF suppression" is nonsense. If anything the added length makes it a better receiving antenna for radios with RF problems! And there is zero magic to 600 ohms -- we haven't matched impedances in audio for nearly 50 years! It's simply a low impedance mic, and virtually all mics used in ham radio have been low impedance for at least that long. I've been using a CM500 for about ten years, and the only thing that breaks is the cable, because I'm really a klutz with headsets. It's not replaceable, and I don't see a note that the cable in this one is either. If I'm not mistaken, the excellent Sennheiser headset DOES have a replaceable cable. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Inrad W1 Headset and K3
I used mine this weekend, I am very happy with them. The headset has a 1/4 stereo phone plug that is quite robust when compared with a 3.5 mm plug and an adapter. The cable is long and seems sturdy. Very comfortable over the ear phones with good isolation. Has a boom mike that I can push out of the way for a CW contest. I’m glad I bought them. 73 de Dick, K6KR > On Feb 18, 2019, at 16:40, Jorge Diez - CX6VM wrote: > > hello > > anyone use the new Inrad W1 Headset with K3? > > What´s the headset connectors, both 3.5 mm like CM500? > > thanks for the info! > > -- > 73, > Jorge > CX6VM/CW5W > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to d...@elecraft.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Inrad W1 Headset and K3
hello anyone use the new Inrad W1 Headset with K3? What´s the headset connectors, both 3.5 mm like CM500? thanks for the info! -- 73, Jorge CX6VM/CW5W __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KX3 Shutdown and Power up problems.
Bernie, Do you have a saved configuration file for that KX3 from a time it was working properly? If so, you can do an EEINIT (Reset to Factory Defaults) - see the manual for the procedure. The reset will lose the calibration data and any menu settings that you have added. That is why the saved configuration file is important - restore the configuration file using KX3 Utility. If you have no other recourse, you can request the factory configuration file from supp...@elecraft.com. Be sure to specify your serial number. If the EEINIT does not correct it, you can ask for an RSA to send it in for service. If you prefer, it can be sent to the service facility in Italy. 73, Don W3FPR On 2/18/2019 5:57 PM, BERNARD COLLINS via Elecraft wrote: My KX3 has developed a problem after a power interrupt/restore carried out by my mistake. With batteries fitted it will no longer fully power down, it stays orange with (7) *** stars showing on screen and Delta f light on and OFS and B green lights on. I have to disconnect all power to the unit to fully shutdown ie pull out one battery and no external supply. i have run utility and down loaded the latest firmware programes several times with no success as per page 25 of the manual. On re establishing power to KX3 either external or battery radio starts up automatically and is working. i would be great full of any suggestions from the group. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Searching for Noise (i.e., Samples Thereof)
Don't forget to turn off all uninterruptable power supplies too... 73 Frank W3LPL - Original Message - From: "Bob McGraw K4TAX" To: elecraft@mailman.qth.net Sent: Monday, February 18, 2019 8:36:13 PM Subject: Re: [Elecraft] Searching for Noise (i.e., Samples Thereof) One of the first things to do is isolate the noise to two sources in general. (a) inside the house, (b) outside the house. My approach is to use the 12V battery off of the lawn tractor to power the transceiver. Use the antenna and band which provides the worst noise. Then pull the main breaker for the house. What's the noise difference? If there is little to no difference, the noise is outside of the house. If the noise drops a noticeable amount, that part of the noise is inside the house. The MFJ 805 works well for finding noise inside the house. To further look for (a), turn all breakers off and the main back on. Noise should be about the same. Then add one breaker at a time and observe the noise. Yes, I know this takes many trips between the breaker panel and the radio. When you flip a breaker ON and the noise increases, that tells one what circuit and area of the house the noise is originating. Find it and eliminate it. Then move on to other breakers in the panel doing the same thing. This is simply the process of logically identifying the noise and then applying means to reduce or eliminate the noise. If it is outside of the house than an item such as the MFJ 852 works well. The NB and NR functions work well in the K3S but they are no substitute for finding and eliminating the noise source. 73 Bob, K4TAX On 2/18/2019 12:41 PM, John Simmons wrote: > Dave, > > Yeah I'd like to see that too. I'm lucky that my nearest neighbor is > 300 feet away and we have underground power. EVERY noise I've heard on > either HF, VHF or UHF has originated on my premises. > > 73, > -John NI0K > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to donov...@starpower.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] KX3 Shutdown and Power up problems.
My KX3 has developed a problem after a power interrupt/restore carried out by my mistake. With batteries fitted it will no longer fully power down, it stays orange with (7) *** stars showing on screen and Delta f light on and OFS and B green lights on. I have to disconnect all power to the unit to fully shutdown ie pull out one battery and no external supply. i have run utility and down loaded the latest firmware programes several times with no success as per page 25 of the manual. On re establishing power to KX3 either external or battery radio starts up automatically and is working. i would be great full of any suggestions from the group. regards Bernie MW0GBW __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Searching for Noise (i.e., Samples Thereof)
On 2/18/2019 12:36 PM, Bob McGraw K4TAX wrote: One of the first things to do is isolate the noise to two sources in general. (a) inside the house, (b) outside the house. My approach is to use the 12V battery off of the lawn tractor to power the transceiver. Use the antenna and band which provides the worst noise. Great advice. BUT -- when doing this, make sure that all UPS units are powered off, both because they are noise sources themselves, and because they keep some equipment running that's also likely to be a noise source. Lots more detailed advice in http://k9yc.com/KillingReceiveNoise.pdf Another important delineation of noise type is between 1) electronic noise, generated by electronic equipment, solar power systems, variable speed motor controllers, and switch mode power supplies; and 2) impulse noise, mostly generated by arcing on power lines, electric fences, and neon signs. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Searching for Noise (i.e., Samples Thereof)
One of the first things to do is isolate the noise to two sources in general. (a) inside the house, (b) outside the house. My approach is to use the 12V battery off of the lawn tractor to power the transceiver. Use the antenna and band which provides the worst noise. Then pull the main breaker for the house. What's the noise difference? If there is little to no difference, the noise is outside of the house. If the noise drops a noticeable amount, that part of the noise is inside the house. The MFJ 805 works well for finding noise inside the house. To further look for (a), turn all breakers off and the main back on. Noise should be about the same. Then add one breaker at a time and observe the noise. Yes, I know this takes many trips between the breaker panel and the radio. When you flip a breaker ON and the noise increases, that tells one what circuit and area of the house the noise is originating. Find it and eliminate it. Then move on to other breakers in the panel doing the same thing. This is simply the process of logically identifying the noise and then applying means to reduce or eliminate the noise. If it is outside of the house than an item such as the MFJ 852 works well. The NB and NR functions work well in the K3S but they are no substitute for finding and eliminating the noise source. 73 Bob, K4TAX On 2/18/2019 12:41 PM, John Simmons wrote: Dave, Yeah I'd like to see that too. I'm lucky that my nearest neighbor is 300 feet away and we have underground power. EVERY noise I've heard on either HF, VHF or UHF has originated on my premises. 73, -John NI0K __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Searching for Noise (i.e., Samples Thereof)
Dave,
Yeah I'd like to see that too. I'm lucky that my nearest neighbor is 300
feet away and we have underground power. EVERY noise I've heard on
either HF, VHF or UHF has originated on my premises.
73,
-John NI0K
Dave New, N8SBE wrote on 2/18/2019 12:23 PM:
I've always wanted to better understand the tweaks/handles that we have
in the noise blanker/noise reduction algorithms in the K3/K3S. I can
'frob the knobs', until I see some reduction in noise, but I felt it
would be much better to not be flying blind, and be able to know just
what the various modes do and their parameters do, and be able to
actually see some better noise signature to get an idea of whether or
not a particular tweak is doing what I thought it was doing.
I have the Fred Cady book, and it goes into some detail, but I'd like to
see a much better description from the source as to just what all those
parameters actually do, and a means to see it actually happen, on the
P3, or a scope, hooked to the IF out or similar.
I'm plagued with all sorts of noise at my QTH, and I haven't spent much
time trying to hunt it all down. I feel I need better insight than to
just go around pulling circuit breakers. Some of the stuff is quite
likely to be off-premise, as well, which brings me back to likely having
to deal with it as best I can at the receiver end of it.
Thanks and 73,
-- Dave, N8SBE
Original Message
Subject: [Elecraft] Searching for Noise (i.e., Samples Thereof)
From: Wayne Burdick
Date: Sat, February 16, 2019 5:56 pm
To: Elecraft Reflector
As time permits, we're trying to better characterize the RF noise that
plagues stations at various locations.
__
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Message delivered to jasimm...@pinewooddata.com
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Re: [Elecraft] Searching for Noise (i.e., Samples Thereof)
I've always wanted to better understand the tweaks/handles that we have in the noise blanker/noise reduction algorithms in the K3/K3S. I can 'frob the knobs', until I see some reduction in noise, but I felt it would be much better to not be flying blind, and be able to know just what the various modes do and their parameters do, and be able to actually see some better noise signature to get an idea of whether or not a particular tweak is doing what I thought it was doing. I have the Fred Cady book, and it goes into some detail, but I'd like to see a much better description from the source as to just what all those parameters actually do, and a means to see it actually happen, on the P3, or a scope, hooked to the IF out or similar. I'm plagued with all sorts of noise at my QTH, and I haven't spent much time trying to hunt it all down. I feel I need better insight than to just go around pulling circuit breakers. Some of the stuff is quite likely to be off-premise, as well, which brings me back to likely having to deal with it as best I can at the receiver end of it. Thanks and 73, -- Dave, N8SBE Original Message Subject: [Elecraft] Searching for Noise (i.e., Samples Thereof) From: Wayne Burdick Date: Sat, February 16, 2019 5:56 pm To: Elecraft Reflector As time permits, we're trying to better characterize the RF noise that plagues stations at various locations. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Searching for Noise (i.e., Samples Thereof)
__ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] low pass filters
OT: A caution related to external low-pass filters … Many were made with cutoff frequencies -below- 6M and these exhibited high reflected power above 10M. Trivia, FWIW 73! Ken - K0PP On Sun, Feb 17, 2019 at 4:26 PM Don Wilhelm wrote: > A low-pass filter will not change RFI either coming into the shack or > going out. There are low-pass filters in all transceivers produced by > Elecraft (and most other manufacturers), and they are in both the > transmit and receive path. > The current FCC requirement is for the 2nd harmonic be suppressed by 43 > dB over the fundamental. > Low pass filters come from a past era when the FCC requirements were not > as stringent and TVs responded to those higher order harmonics from > amateur transmitters. That is no longer the case. > > Considering receive, we do have many sources of unintentional radiation > which is present in the HF spectrum, and other than locating and having > the offending device turned off, there is not much we can do about it. > Although if it is interfering with licensed operation, there is recourse > by cooperation with the FCC. The products giving problems range from > inexpensive switching power sources (read wall-warts) to control > circuits in many household appliances and other consumer devices, and > even some lighting products. > > If you are operating in an environment like Field Day where there are > multiple transmitters operating in close proximity, bandpass filters and > single band antennas are the normal "cure" as well as physical > separation of the antennas. > > 73, > Don W3FPR > > > > On 2/17/2019 5:59 PM, Richards wrote: > > Good day - What is the consensus concerning low-pass filters to > > minimize RFI both coming in and going out of the shack? Is there a > > type or size, brand or model that comes highly recommended? Is it > > prudent to employ one, regardless of whether or not there is a known, > > identified problem , i.e., just in case? Does it assist reception as > > well as transmission? > > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to kengk...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] P3TXMON
This last fall I installed the P3TXMON in my P3, using the DCHF-200 coupler. I guess I never checked this on 40M, but this weekend during the CW DX contest I found that I could not use 40M: I got so much RF entering the PC via the USB port that my logging program locked up and I had to reboot the PC. Got to thinking about the discussion recently on this reflector about the PL-259 discussion, and checked my installation. The coax was in good shape and properly tightened down to the coupler. However, the SO-239 connectors on the DCHF-200 were VERY loose! Tightened these down, and all is well on 40M again. Folks using one of the Elecraft couplers might want to check that the SO-239 connectors are firmly tightened down! 73, Tom W4KX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Looking for a way to switch an antenna input to the KAT500
W2VJN and N3RD from Top Ten Devices are great helpful guys. I have been using their band decoders for decades and we have both operated from the same station in St Croix. I also have a Top Ten 6 way antenna relay box that I only use only on contest expeditions with a single radio. It is small, light weight and easily fits in my suitcase. This is not a heavy-duty relay, you cannot run legal limit RTTY though it. Also the SO-239 center connectors are recessed which might cause an issue with some crimped PL-259's. To use their relays for an SO2R station would require a lot of relay boxes and they claim isolation >40dB. For me a single 2 x 6 box is a better choice, Array Solutions SixPak claims >55dB which Jim confirmed. John KK9A Jim Brown K9YC wrote: On 2/17/2019 6:26 PM, Randy Farmer wrote: > I concur with the comments on the Top Ten 2-way switches. I'm using > about 10 of them at various places in my SO2R contest station antenna > and BPF switching networks. They work well and have good isolation. I On the basis of my measurements with a Vector Network Analyzer, I am NOT impressed with these switches, and consider them poorly designed. The major design flaw is that they depend upon the chassis for signal return, so the signal path gets increasingly badly mismatched at 15M and above. I didn't measure crosstalk, but this design error would certainly impact it. I reduced the mismatch by about half by adding braid from the coax connectors to the circuit board and following (as best I could) the signal path to provide a return. Why? Because the "ground" layer is broken under the top layer, so it can't act as a return either! Someone cited 50 dB as "good isolation." When I replaced my WX0B 6x2, I measured isolation of about 55 dB. The replacement, a 4O3A 6x2, measured 75 dB worst case. And other one I'm using now, the 4O3A Antenna Genius, measures better than 95 dB worst case. If you look inside a well designed power amp, you'll see transmission line running from input and output for both TX and RX path. My Ten Tec Titans were built that way, and so is the KPA500. You'll also see mini-coax jumpers tying sections of the K3 together. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
