Re: [Elecraft] Band pass filters
When you buy RA6LBS filters each comes with a tracing by a spectrum analyzer showing the exact filter characteristics. On each of these that I own the tracing matches the Rigol with tracking generator. They really work well. I have a complete set of 500 watt filters from RA6LBS. They are sold by DXengineering. My other set is VA6AM they also provide 80 to 100 dB of rejection with a 3500 watt rating. The cost of those filters with switch, multiplexers and cabling is more expensive than many people have invested in their radio alone. In conclusion, investing in a heavy duty set of filters is cheaper than blowing up a radio. Plus, it gives one more options. 73, Morgan NJ8M BS + MS + $2.98 = COFFEE Real Life Experience = Priceless, says the man who set his back yard on fire with a breadboard tuner loading a 160 meter inverted L with 1000 watts. LOL On Tue, Jul 27, 2021 at 9:55 PM Jim Brown wrote: > On 7/27/2021 12:53 PM, Morgan Bailey wrote: > > 80 to 100 dB band to band attenuation is necessary for a contest station. > > That depends a LOT on the radios and the amps. > > > Reviewing Contest University the RA6LBS talk from a few years ago is the > > basis for this decision. He probably has the most experience in this > field > > beside that of VA6AM. Both make great filters. Just having a filter is > not > > enough. One needs a multiplexer in conjunction with the band pass filter > to > > get to that DB level. One could stack 2 band pass filters and attain > > whatever is needed to get the job done. The multi switchable boxes that > run > > about 500 to 900 dollars only give about 30 to maybe 40 db of rejection. > > That also depends a LOT on the boxes, and some are far better than > others. See this study I did about 8 years ago for National Contest > Journal. http://k9yc.com/BandpassFilterSurvey.pdf Several of the units > are 10-20 dB better than that. > It > > is just not enough to keep the other radio quiet and SAFE from front in > > overload and toasting the receiver circuits. I use transmitting band pass > > filters rated at 3500 watts on the output of my amp. > > This is a very good way to do it. Most hams overlook the harmonics and > IMD generated in power amps. > This coupled with > > multiplexers on 160/80/40 and 20/15/10 makes for a multi two or an SO2R > > setup quiet on each radio. Between the multiplexer and associated band > pass > > filters I am able to run 1.5KW 160-10 with an antenna farm that takes up > 68 > > linear feet total for 160-10. Additionally, 160/80/40 are vertical > > polarized and 20/15/10 are horizontal polarized adding more rejection. It > > works and works well. > > > > One problem that many stations on a small lot have is ignoring Common > Mode > > pick up off the shield of the coax. Grounding all shields before entering > > the shack > > YES! AND seriously bonding everything in the shack and the building that > contains it. > > and using 1:1 choke baluns is a necessary step to prevent > > interstation interference. > > Yes, it's quite important to have a SERIOUS common mode choke at the > feedpoint of EVERY antenna. http://k9yc.com/2018Cookbook.pdf > > > > Having radios with very low composite/Phase noise is necessary. > > YES! > > At the last Visalia DX Convention, gave an overview talk on a dozen or > so mechanisms that contribute to inter-station interference, and how to > minimize each. It's here. http://k9yc.com/Multi-Station.pdf > > And W2VJN's book on the subject is excellent. > > 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 mbaileyc...@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] Band pass filters
On 7/27/2021 12:53 PM, Morgan Bailey wrote: 80 to 100 dB band to band attenuation is necessary for a contest station. That depends a LOT on the radios and the amps. Reviewing Contest University the RA6LBS talk from a few years ago is the basis for this decision. He probably has the most experience in this field beside that of VA6AM. Both make great filters. Just having a filter is not enough. One needs a multiplexer in conjunction with the band pass filter to get to that DB level. One could stack 2 band pass filters and attain whatever is needed to get the job done. The multi switchable boxes that run about 500 to 900 dollars only give about 30 to maybe 40 db of rejection. That also depends a LOT on the boxes, and some are far better than others. See this study I did about 8 years ago for National Contest Journal. http://k9yc.com/BandpassFilterSurvey.pdf Several of the units are 10-20 dB better than that. It is just not enough to keep the other radio quiet and SAFE from front in overload and toasting the receiver circuits. I use transmitting band pass filters rated at 3500 watts on the output of my amp. This is a very good way to do it. Most hams overlook the harmonics and IMD generated in power amps. This coupled with multiplexers on 160/80/40 and 20/15/10 makes for a multi two or an SO2R setup quiet on each radio. Between the multiplexer and associated band pass filters I am able to run 1.5KW 160-10 with an antenna farm that takes up 68 linear feet total for 160-10. Additionally, 160/80/40 are vertical polarized and 20/15/10 are horizontal polarized adding more rejection. It works and works well. One problem that many stations on a small lot have is ignoring Common Mode pick up off the shield of the coax. Grounding all shields before entering the shack YES! AND seriously bonding everything in the shack and the building that contains it. and using 1:1 choke baluns is a necessary step to prevent interstation interference. Yes, it's quite important to have a SERIOUS common mode choke at the feedpoint of EVERY antenna. http://k9yc.com/2018Cookbook.pdf Having radios with very low composite/Phase noise is necessary. YES! At the last Visalia DX Convention, gave an overview talk on a dozen or so mechanisms that contribute to inter-station interference, and how to minimize each. It's here. http://k9yc.com/Multi-Station.pdf And W2VJN's book on the subject is excellent. 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] Band pass filters
David I purchased blank PCBs from VA6AM along with the torroids with a view to building a switched filter set. Still on my list of “want to do” and my motivation was driven by space reduction in my portable SO2R project. However I’ve somewhat learnt the hard way to be honest with myself upfront on time and effort versus paying an arm and a leg for a commercial solution. Paul > On Jul 27, 2021, at 1:42 PM, CUTTER DAVID via Elecraft > wrote: > > Thanks all for the great advice and the further reading. > > In my specific case of K3S + KPA500 + KAT500, is there no room to reduce the > high performance W3NQM filters? > > I understand common mode filters and have made good versions of these from > K9YC cookbook. They remain in circuit all the time, so that's easy, whilst > NQN filters have to be replaced for each band change, so, even I want to have > a quick peek at another band, it still takes minutes to swap around the > filters with the other station. It's a painful loss of time and prone to > getting it wrong. Building a lower specification filter set with relay > switching would be easier. > > David G3UNA > > >> On 27 July 2021 at 20:53 Morgan Bailey wrote: >> >> >> 80 to 100 dB band to band attenuation is necessary for a contest station. >> Reviewing Contest University the RA6LBS talk from a few years ago is the >> basis for this decision. He probably has the most experience in this field >> beside that of VA6AM. Both make great filters. Just having a filter is not >> enough. One needs a multiplexer in conjunction with the band pass filter to >> get to that DB level. One could stack 2 band pass filters and attain >> whatever is needed to get the job done. The multi switchable boxes that run >> about 500 to 900 dollars only give about 30 to maybe 40 db of rejection. It >> is just not enough to keep the other radio quiet and SAFE from front in >> overload and toasting the receiver circuits. I use transmitting band pass >> filters rated at 3500 watts on the output of my amp. This coupled with >> multiplexers on 160/80/40 and 20/15/10 makes for a multi two or an SO2R >> setup quiet on each radio. Between the multiplexer and associated band pass >> filters I am able to run 1.5KW 160-10 with an antenna farm that takes up 68 >> linear feet total for 160-10. Additionally, 160/80/40 are vertical >> polarized and 20/15/10 are horizontal polarized adding more rejection. It >> works and works well. >> >> One problem that many stations on a small lot have is ignoring Common Mode >> pick up off the shield of the coax. Grounding all shields before entering >> the shack and using 1:1 choke baluns is a necessary step to prevent >> interstation interference. >> >> Having radios with very low composite/Phase noise is necessary. I use >> FTDX101 radios in the shack. If radios are noisy and they raise the noise >> floor of the other radio during reception, about the only solution is to >> get a new radio that is clean on the output. Check out the Sherwood >> engineering pages for those ratings. While you are there, one may want to >> check out the ratings of ADC front ends vs Superhet front ends.Hybrid >> superhet/ADC front end receivers seem to be the best choice for this >> environment at the moment. RMDR and Close in blocking dynamic range are the >> magic numbers to review. >> >> 73, Morgan Bailey NJ8M >> >> BS + MS + $2.98 = COFFEE >> Real Life Experience = Priceless, says the man who set his back yard on >> fire with a breadboard tuner loading a 160 meter inverted L with 1000 >> watts. LOL >> >> >>> On Tue, Jul 27, 2021 at 1:52 PM David Hachadorian >>> wrote: >>> >>> You need a filter on the TX radio to prevent its phase noise from being >>> heard on other bands. Just pressing PTT on the TX radio, even without >>> putting out any measurable power, will raise the noise floor on multiple >>> bands. With suitable band decoders driving filter selection, >>> fast-switching between bands is possible. >>> >>> Dave Hachadorian, K6LL >>> Yuma, AZ >>> >>> >>> On 7/27/2021 9:09 AM, CUTTER DAVID via Elecraft wrote: Given the improved performance of modern transceivers, is there still a >>> call for high specification W3NQN band pass filters in a 2-transmitter >>> station? For example on a Multi-2 contest environment. For instance K3S + >>> KPA + KAT. The filter fitted between radio and amplifier. I have the *feeling* that a receive-only filter (with tx bypass) might >>> be all that is needed. This is much easier to implement than a full >>> transmitter-rated set making fast switching between bands (eg for a quick >>> look around) very quick and easy from the keyboard, etc. David G3UNA > __ > 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
Re: [Elecraft] Band pass filters
Thanks all for the great advice and the further reading. In my specific case of K3S + KPA500 + KAT500, is there no room to reduce the high performance W3NQM filters? I understand common mode filters and have made good versions of these from K9YC cookbook. They remain in circuit all the time, so that's easy, whilst NQN filters have to be replaced for each band change, so, even I want to have a quick peek at another band, it still takes minutes to swap around the filters with the other station. It's a painful loss of time and prone to getting it wrong. Building a lower specification filter set with relay switching would be easier. David G3UNA > On 27 July 2021 at 20:53 Morgan Bailey wrote: > > > 80 to 100 dB band to band attenuation is necessary for a contest station. > Reviewing Contest University the RA6LBS talk from a few years ago is the > basis for this decision. He probably has the most experience in this field > beside that of VA6AM. Both make great filters. Just having a filter is not > enough. One needs a multiplexer in conjunction with the band pass filter to > get to that DB level. One could stack 2 band pass filters and attain > whatever is needed to get the job done. The multi switchable boxes that run > about 500 to 900 dollars only give about 30 to maybe 40 db of rejection. It > is just not enough to keep the other radio quiet and SAFE from front in > overload and toasting the receiver circuits. I use transmitting band pass > filters rated at 3500 watts on the output of my amp. This coupled with > multiplexers on 160/80/40 and 20/15/10 makes for a multi two or an SO2R > setup quiet on each radio. Between the multiplexer and associated band pass > filters I am able to run 1.5KW 160-10 with an antenna farm that takes up 68 > linear feet total for 160-10. Additionally, 160/80/40 are vertical > polarized and 20/15/10 are horizontal polarized adding more rejection. It > works and works well. > > One problem that many stations on a small lot have is ignoring Common Mode > pick up off the shield of the coax. Grounding all shields before entering > the shack and using 1:1 choke baluns is a necessary step to prevent > interstation interference. > > Having radios with very low composite/Phase noise is necessary. I use > FTDX101 radios in the shack. If radios are noisy and they raise the noise > floor of the other radio during reception, about the only solution is to > get a new radio that is clean on the output. Check out the Sherwood > engineering pages for those ratings. While you are there, one may want to > check out the ratings of ADC front ends vs Superhet front ends.Hybrid > superhet/ADC front end receivers seem to be the best choice for this > environment at the moment. RMDR and Close in blocking dynamic range are the > magic numbers to review. > > 73, Morgan Bailey NJ8M > > BS + MS + $2.98 = COFFEE > Real Life Experience = Priceless, says the man who set his back yard on > fire with a breadboard tuner loading a 160 meter inverted L with 1000 > watts. LOL > > > On Tue, Jul 27, 2021 at 1:52 PM David Hachadorian > wrote: > > > You need a filter on the TX radio to prevent its phase noise from being > > heard on other bands. Just pressing PTT on the TX radio, even without > > putting out any measurable power, will raise the noise floor on multiple > > bands. With suitable band decoders driving filter selection, > > fast-switching between bands is possible. > > > > Dave Hachadorian, K6LL > > Yuma, AZ > > > > > > On 7/27/2021 9:09 AM, CUTTER DAVID via Elecraft wrote: > > > Given the improved performance of modern transceivers, is there still a > > call for high specification W3NQN band pass filters in a 2-transmitter > > station? For example on a Multi-2 contest environment. For instance K3S + > > KPA + KAT. The filter fitted between radio and amplifier. > > > > > > I have the *feeling* that a receive-only filter (with tx bypass) might > > be all that is needed. This is much easier to implement than a full > > transmitter-rated set making fast switching between bands (eg for a quick > > look around) very quick and easy from the keyboard, etc. > > > > > > David G3UNA __ 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] Band pass filters
Bird makes a very good bandpass filter for the SDR radio you are speaking of... It gets rid of ALL phase noise on all bands at once. 73, and thanks, Dave (NK7Z) https://www.nk7z.net ARRL Volunteer Examiner ARRL Technical Specialist, RFI ARRL Asst. Director, NW Division, Technical Resources On 7/27/21 12:50 PM, Bill Steffey NY9H wrote: well said at field day that famous SDR, very reasonably priced, abundant with features DID INDEED SPREAD wide band noise ..it was on 10 and wiped out all thru 80 meters on three other radios of various makes. ( mine was a k3) ... maybe all we needed was to have bandpass filters for THAT radio ... but 4 band of good filters starts to move into the purchase price of that radio Sherwood has spoken of this...and hope he will be elaborating ... as I hate being the bearer of bad news bill ny9h On 7/27/2021 2:49 PM, David Hachadorian wrote: You need a filter on the TX radio to prevent its phase noise from being heard on other bands. Just pressing PTT on the TX radio, even without putting out any measurable power, will raise the noise floor on multiple bands. With suitable band decoders driving filter selection, fast-switching between bands is possible. Dave Hachadorian, K6LL Yuma, AZ On 7/27/2021 9:09 AM, CUTTER DAVID via Elecraft wrote: Given the improved performance of modern transceivers, is there still a call for high specification W3NQN band pass filters in a 2-transmitter station? For example on a Multi-2 contest environment. For instance K3S + KPA + KAT. The filter fitted between radio and amplifier. I have the *feeling* that a receive-only filter (with tx bypass) might be all that is needed. This is much easier to implement than a full transmitter-rated set making fast switching between bands (eg for a quick look around) very quick and easy from the keyboard, etc. David G3UNA __ 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 k6ll.d...@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 d...@nk7z.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] Band pass filters
80 to 100 dB band to band attenuation is necessary for a contest station. Reviewing Contest University the RA6LBS talk from a few years ago is the basis for this decision. He probably has the most experience in this field beside that of VA6AM. Both make great filters. Just having a filter is not enough. One needs a multiplexer in conjunction with the band pass filter to get to that DB level. One could stack 2 band pass filters and attain whatever is needed to get the job done. The multi switchable boxes that run about 500 to 900 dollars only give about 30 to maybe 40 db of rejection. It is just not enough to keep the other radio quiet and SAFE from front in overload and toasting the receiver circuits. I use transmitting band pass filters rated at 3500 watts on the output of my amp. This coupled with multiplexers on 160/80/40 and 20/15/10 makes for a multi two or an SO2R setup quiet on each radio. Between the multiplexer and associated band pass filters I am able to run 1.5KW 160-10 with an antenna farm that takes up 68 linear feet total for 160-10. Additionally, 160/80/40 are vertical polarized and 20/15/10 are horizontal polarized adding more rejection. It works and works well. One problem that many stations on a small lot have is ignoring Common Mode pick up off the shield of the coax. Grounding all shields before entering the shack and using 1:1 choke baluns is a necessary step to prevent interstation interference. Having radios with very low composite/Phase noise is necessary. I use FTDX101 radios in the shack. If radios are noisy and they raise the noise floor of the other radio during reception, about the only solution is to get a new radio that is clean on the output. Check out the Sherwood engineering pages for those ratings. While you are there, one may want to check out the ratings of ADC front ends vs Superhet front ends.Hybrid superhet/ADC front end receivers seem to be the best choice for this environment at the moment. RMDR and Close in blocking dynamic range are the magic numbers to review. 73, Morgan Bailey NJ8M BS + MS + $2.98 = COFFEE Real Life Experience = Priceless, says the man who set his back yard on fire with a breadboard tuner loading a 160 meter inverted L with 1000 watts. LOL On Tue, Jul 27, 2021 at 1:52 PM David Hachadorian wrote: > You need a filter on the TX radio to prevent its phase noise from being > heard on other bands. Just pressing PTT on the TX radio, even without > putting out any measurable power, will raise the noise floor on multiple > bands. With suitable band decoders driving filter selection, > fast-switching between bands is possible. > > Dave Hachadorian, K6LL > Yuma, AZ > > > On 7/27/2021 9:09 AM, CUTTER DAVID via Elecraft wrote: > > Given the improved performance of modern transceivers, is there still a > call for high specification W3NQN band pass filters in a 2-transmitter > station? For example on a Multi-2 contest environment. For instance K3S + > KPA + KAT. The filter fitted between radio and amplifier. > > > > I have the *feeling* that a receive-only filter (with tx bypass) might > be all that is needed. This is much easier to implement than a full > transmitter-rated set making fast switching between bands (eg for a quick > look around) very quick and easy from the keyboard, etc. > > > > David G3UNA > > __ > > 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 k6ll.d...@gmail.com > > . > > -- > Dave Hachadorian, K6LL > Big Bear Lake, AZ > > __ > 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 mbaileyc...@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] Band pass filters
well said at field day that famous SDR, very reasonably priced, abundant with features DID INDEED SPREAD wide band noise ..it was on 10 and wiped out all thru 80 meters on three other radios of various makes. ( mine was a k3) ... maybe all we needed was to have bandpass filters for THAT radio ... but 4 band of good filters starts to move into the purchase price of that radio Sherwood has spoken of this...and hope he will be elaborating ... as I hate being the bearer of bad news bill ny9h On 7/27/2021 2:49 PM, David Hachadorian wrote: You need a filter on the TX radio to prevent its phase noise from being heard on other bands. Just pressing PTT on the TX radio, even without putting out any measurable power, will raise the noise floor on multiple bands. With suitable band decoders driving filter selection, fast-switching between bands is possible. Dave Hachadorian, K6LL Yuma, AZ On 7/27/2021 9:09 AM, CUTTER DAVID via Elecraft wrote: Given the improved performance of modern transceivers, is there still a call for high specification W3NQN band pass filters in a 2-transmitter station? For example on a Multi-2 contest environment. For instance K3S + KPA + KAT. The filter fitted between radio and amplifier. I have the *feeling* that a receive-only filter (with tx bypass) might be all that is needed. This is much easier to implement than a full transmitter-rated set making fast switching between bands (eg for a quick look around) very quick and easy from the keyboard, etc. David G3UNA __ 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 k6ll.d...@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] Band pass filters
You need a filter on the TX radio to prevent its phase noise from being heard on other bands. Just pressing PTT on the TX radio, even without putting out any measurable power, will raise the noise floor on multiple bands. With suitable band decoders driving filter selection, fast-switching between bands is possible. Dave Hachadorian, K6LL Yuma, AZ On 7/27/2021 9:09 AM, CUTTER DAVID via Elecraft wrote: Given the improved performance of modern transceivers, is there still a call for high specification W3NQN band pass filters in a 2-transmitter station? For example on a Multi-2 contest environment. For instance K3S + KPA + KAT. The filter fitted between radio and amplifier. I have the *feeling* that a receive-only filter (with tx bypass) might be all that is needed. This is much easier to implement than a full transmitter-rated set making fast switching between bands (eg for a quick look around) very quick and easy from the keyboard, etc. David G3UNA __ 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 k6ll.d...@gmail.com . -- Dave Hachadorian, K6LL Big Bear Lake, AZ __ 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] Band pass filters
Hi Paul Thanks for those thoughts. I see your point re sharing a tri-bander and that looks like a severe case. Looking at the number of filters already in place and the low spurii expected of Elecraft gear, it looks worth considering to down-grade the extra filters. For instance, the KPA amplifier has low pass filters on its input and output, then the atu has a filtering effect. I wouldn't know what this adds up to, but when the W3NQN filters were designed, things were very different. 73 David G3UNA > On 27 July 2021 at 17:30 Paul GACEK wrote: > > > Hi David > > I think any answer is dependent on the station configuration. > > For example, if the M/2 station is sharing a single tribander (i.e. one on > 20m and another on 15m) then I imagine filters are still essential as a > tri-plexer will only provide so much isolation. > > Another example; If a less than optimal 2xn antenna switch is used (i.e. > doesn’t provide excellent isolation) then filters can help to minimize > interference. > > These observations are based on my limited experience building a portable > SO2R station and separately a short time owning a Flex 6600M that had “state > of the art” internal filters. Reading the Flex manual seemed to suggest that > all bets are off when power exceeds 100w and you want to transmit on one port > and listen on another. > > Paul > W6PNG/M0SNA > www.nomadic.blog > > > On Jul 27, 2021, at 9:09 AM, CUTTER DAVID via Elecraft > > wrote: > > > > Given the improved performance of modern transceivers, is there still a > > call for high specification W3NQN band pass filters in a 2-transmitter > > station? For example on a Multi-2 contest environment. For instance K3S + > > KPA + KAT. The filter fitted between radio and amplifier. > > > > I have the *feeling* that a receive-only filter (with tx bypass) might be > > all that is needed. This is much easier to implement than a full > > transmitter-rated set making fast switching between bands (eg for a quick > > look around) very quick and easy from the keyboard, etc. > > > > David G3UNA __ 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] Band pass filters
Hi David I think any answer is dependent on the station configuration. For example, if the M/2 station is sharing a single tribander (i.e. one on 20m and another on 15m) then I imagine filters are still essential as a tri-plexer will only provide so much isolation. Another example; If a less than optimal 2xn antenna switch is used (i.e. doesn’t provide excellent isolation) then filters can help to minimize interference. These observations are based on my limited experience building a portable SO2R station and separately a short time owning a Flex 6600M that had “state of the art” internal filters. Reading the Flex manual seemed to suggest that all bets are off when power exceeds 100w and you want to transmit on one port and listen on another. Paul W6PNG/M0SNA www.nomadic.blog > On Jul 27, 2021, at 9:09 AM, CUTTER DAVID via Elecraft > wrote: > > Given the improved performance of modern transceivers, is there still a call > for high specification W3NQN band pass filters in a 2-transmitter station? > For example on a Multi-2 contest environment. For instance K3S + KPA + KAT. > The filter fitted between radio and amplifier. > > I have the *feeling* that a receive-only filter (with tx bypass) might be all > that is needed. This is much easier to implement than a full > transmitter-rated set making fast switching between bands (eg for a quick > look around) very quick and easy from the keyboard, etc. > > David G3UNA > __ > 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 paul.ga...@me.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] Band Pass Filters for QRP
Once very simple solution that will provide more than 30 dB attenuation of the undesired signal is a coax stub. It's just a length of coax connected to the main transmission line with a T connector that is cut to the proper length to attenuate the signal from the other station. And, yes, you can use several of them in parallel. A couple of on-line references for building them are: http://www.k1ttt.net/technote/onestub.html http://www.k1ttt.net/technote/onestub.html 73, Ron AC7AC -Original Message- Good afternoon all. I have a question and would appreciate everyone's thoughts. I've started trying to get to the field with a buddy of mine. We take a popup camper and have a day or two operating event. We keep running into a problem if we both decide to set up stations. We are generally using K3s and W3EDP antennas or maybe a Buddipole. The antennas are 20-30 feet apart, so as you might guess, If one of us is on 40, the guy operating on 20 knows it and visa versa. While the K3 can do alot to minimize the interference, it's not something you'd want to listen to for very long. What options might be out there. We are aware of W3NQN bandpass filters, at $105-$125 a band, that can get expensive quick. But that's not the real problem. 6 of them is almost the size of them is almost the size of the radio. I don't really need filters capable of 200W. I'm looking for something closer to QRP levels. Even 20-30W would probably work, as it would allow for some of the backpacker type amps. I know the W3NQN filter, or some of their cloans would do the job, but I'd like something smallerIF I don't have to compromize too much in performance. Any suggestions would be appreciated. 73's Jack K5FSE Treas QRP ARCI jack.nel...@mindspring.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
Re: [Elecraft] Band Pass Filters for QRP
W3NQN wrote a nice series of articles for QST on bandpass filters, a couple of which were targeted specifically for QRP operations during Field Day. The design I liked uses a band reject element at the next harmonic frequency. You can make your own filters from those articles, and they are quite small in size due to the use of small ferrite cores for the inductors. 73, Dave AB7E On 10/27/2011 2:21 PM, Jack Nelson wrote: Good afternoon all. I have a question and would appreciate everyone's thoughts. I've started trying to get to the field with a buddy of mine. We take a popup camper and have a day or two operating event. We keep running into a problem if we both decide to set up stations. We are generally using K3s and W3EDP antennas or maybe a Buddipole. The antennas are 20-30 feet apart, so as you might guess, If one of us is on 40, the guy operating on 20 knows it and visa versa. While the K3 can do alot to minimize the interference, it's not something you'd want to listen to for very long. What options might be out there. We are aware of W3NQN bandpass filters, at $105-$125 a band, that can get expensive quick. But that's not the real problem. 6 of them is almost the size of them is almost the size of the radio. I don't really need filters capable of 200W. I'm looking for something closer to QRP levels. Even 20-30W would probably work, as it would allow for some of the backpacker type amps. I know the W3NQN filter, or some of their cloans would do the job, but I'd like something smallerIF I don't have to compromize too much in performance. Any suggestions would be appreciated. 73's Jack K5FSE Treas QRP ARCI jack.nel...@mindspring.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 __ 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
Re: [Elecraft] Band Pass Filters for QRP
Jack, 20-30 feet separation puts your antennas in each others' near fields, and they become coupled together [i.e. you're trying to receive on conductors that are actually parasitically part of your partner's transmit antenna]. Invest in a roll of coax and get them at least a couple of wavelengths apart, more is better. It'll make a big difference, and may get the QRM down to levels the K3 can handle. You may still need a couple of filters for 80/40 operation, the the higher frequency bands may turn out OK. Don't even think about 80/75 operation, we fried the T/R switch diodes in a K3 when someone tried that at our M/2 CQP expedition. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org On 10/27/2011 2:21 PM, Jack Nelson wrote: We are generally using K3s and W3EDP antennas or maybe a Buddipole. The antennas are 20-30 feet apart, so as you might guess, If one of us is on 40, the guy operating on 20 knows it and visa versa. __ 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
Re: [Elecraft] Band pass filters, was ICE
On 4/28/2011 11:39 AM, Rick Stealey wrote: Actually one of the main reasons the filters are used is in DXpedition or FD setups to restrict the phase noise you transmit to your (phone or cw) part of the band so there can be other stations operating on the same band. So you are protecting the other stations ability to use the band at the same time. This is NOT correct. Bandpass filters are just that -- they PASS the entire ham band, and only STOP signals outside the band. They will have NO effect on phase noise produced by a transmitter on th SAME band. A MUCH narrower filter is needed. W2VJN has published the design for a few multi-stub filters that ARE sharp enough to cut off between phone and CW on relatively wide bands like 160M, 80M, and 10M. It would be a real challenge to make them work on the other bands, which are MUCH narrower as percentage of the TX frequency. The W2VJN designs are in his EXCELLENT book on Managing Interstation Interference, available from the Inrad filter folks. It's worth many times the $25 cost. An important advantage of stubs is that they can be placed at the output of a power amp, so they can attenuate trash produced in the amp as well as trash produced in the transceiver. 73, Jim Brown 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
Re: [Elecraft] Band pass filters, was ICE
This is NOT correct. Bandpass filters are just that -- they PASS the entire ham band, and only STOP signals outside the band. W2VJN has published the design for a few multi-stub filters that ARE sharp enough to cut off between phone and CW on relatively wide bands like 160M, 80M, and 10M. Ok, so I was talking about SHARP bandpass filters. __ 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
Re: [Elecraft] Band pass filters, was ICE
It is much harder to design a bandpass filter narrow enough to pass the CW portion of a band while blocking the phone band or vice versa. But it is not impossible. Several decades ago the Murphy's Marauders contest club had some giant helical resonators that could do the job. As I recall the 20 meter one was the size of a rural mailbox. It had a knob so you could tune it to frequency. Al N1AL On Thu, 2011-04-28 at 12:24 -0700, Jim Brown wrote: Bandpass filters are just that -- they PASS the entire ham band, and only STOP signals outside the band. They will have NO effect on phase noise produced by a transmitter on th SAME band. A MUCH narrower filter is needed. __ 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
Re: [Elecraft] Band pass filters, was ICE
Ok, so I was talking about SHARP bandpass filters. Most of us are only interested in what we can build or buy at reasonable cost (not for a Pentagon budget). What you're suggesting MUST be used at the output of a transmitter to reduce phase noise from the TX, so it would VERY difficult to build (and thus expensive). I've seen a few RX XTAL filters (Inrad makes a few) for use between the antenna and the RX (and could be used at the RX IN/OUT of the K3), but they won't help with TX phase noise that lands on your RX frequency. In practice, the best way to run two rigs on the same band is with lots of separation between antennas and very good radios (like a K3). Remember that we pick up at least 6dB of attenuation by doubling the distance between antennas that are in each other's FAR Field, and even more if in the near field. Several of us who set up country expedition stations for the California QSO Party do that. This past year, we had two good tribanders on tower trailers separated by roughly 150 ft, both aimed to the east coast, and located so that they each was about 90 degrees off axis to the other. With both K3s driving decent 500W amps, we were able to have both rigs on 20M or 15M at the same time and work signals that were S7 or better. To work the weaker stations, we had to put those stations on different bands. 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
Re: [Elecraft] Band Pass Filters
Julius N2WN wrote: I'm looking to modify a MFJ-1025 (ala W8JI) and need to build a couple bandpass filters. My first thought is to steal the filter from the 160M Elecraft board, heck it works great. I do not have the parts for that on hand. I do have the parts for the filter in the KPA. Other than power handling, what are the differences between the two? Is the shape significantly different? I don't have BCB issues at this point, but the preamp in the MFJ is wide open to out of band noise. - Possibly I misunderstand you Julius, but the filters in the KPA100 working at 80m - 10m are Low Pass. Does it use a Bandpass filter on 160m? If you are looking for a filter to knock down MF BC signals if the need arises but pass 160m, I can if you like send you circuits for either High Pass or Bandpass filters - the latter of course attenuate signals / noise above and below 160m. Please let me know off-list. 73, Geoff GM4ESD ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
