KX3 Receive Performance Below 1500 kHz
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KX3 Receive Performance Below 1500 kHz
 
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If this is true then the spec on page 51 of the KX3 manual is very
misleading where is states: "310 kHz - 32 MHz and 44-54 MHz..." I was looking forward to using the KX3 on the new 630m Ham Band recently approved by WRC-2012: 472-478 KHz. The K3 operates down to 490 KHz but no lower so unusable on the new ham band. The KX3 "appeared" to be the first commercially mfd radio able to operate down there. If not then this is a BIG missed opportunity. I use a Clifton Labs Z-10020 MW BC Band Reject filter (540-1700 KHz) which rejects signals inside that band. Signals seen at -50 dBm are reduced to the the -110 dBm noise floor, whereas the signals below 540-KHz are unaffected below about 515 KHz. I have used it with the K3 and my SDR-IQ (which tunes to 500-Hz). There was discussion last fall that the KX3 might be capable of transmitting on 630m. I would like the official word on this before publishing my paper reviewing the KX3 at MUD-2012. 630m will remain the province of the "experimenter" if no commercial "shelf-ready" equipment is available. 73, Ed - KL7UW I run 100w into a 43x122 foot inverted-L on 600m under the license WD2XSH/45. ------------------ Date: Sat, 7 Jul 2012 08:15:31 -0500 (GMT-05:00) From: Mike Morrow <[hidden email]> Subject: [Elecraft] KX3 Receive Performance Below 1500 kHz To: [hidden email] Message-ID: <[hidden email]> Content-Type: text/plain; charset=UTF-8 A discussion of KX3 MF lack of sensitivity recently took place on the KX3 list. The KX3 should not be considered really usable below about 1500 kHz, as Wayne explsined: ---- Original Message (from KX3 list) > I thought there was some advantage to AM BCB reception > to be had with the KXAT3. If a KXAT3 is installed, harmonic images are attenuated, but this has little effect on signal strength. > Why wouldn't the T/R PIN diodes be as well protected by > high pass filtering that rolled off below 400 kHz rather > than 1500 kHz The carrier lifetime of the diodes is roughly 1.5 microseconds. This means that strong signals at the low end of the broadcast band could cause IMD (IP2) if not attenuated. The HPF provides about 20-30 dB of rolloff by this frequency, ensuring that this isn't a problem. The KX3 is optimized for ham-band use so this is entirely appropriate. Wayne 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep [hidden email] "Kits made by KL7UW" http://www.kl7uw.com/kits.htm ====================================== ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: KX3 Receive Performance Below 1500 kHz
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Hi Ed,
The KX3's spec also says, "Note: Sensitivity decreases gradually below 1.5 MHz due to protective high-pass filtering...." We did this to ensure that the PIN diodes in the T/R switch are protected. A fairly large amount of attenuation is required by the time you get down to 500 kHz or lower. We did do some transmit tests in the 470 kHz range. We can easily get +10 or possibly +20 dBm output at these frequencies, but you'd need an external filter/amplifier to obtain useful transmit power output. Given that, I would think that an external receiving converter that shifted the 0-1 MHz range up to 7-8 MHz on the KX3 would also be a good solution. The KX3 has transverter bands that can be set up for this application, allowing the VFO to read correctly when on this band. The ACC2 GPIO pin could be used to turn the external converter on/off. The K3 has the same high-pass filtering in the main antenna path as the KX3. But the K3 also provides a way to bypass the filter, by using the KXV3's RX ANT input (or the XVTR input). 73, Wayne N6KR On Jul 8, 2012, at 12:22 AM, Edward R. Cole wrote: > If this is true then the spec on page 51 of the KX3 manual is very > misleading where is states: > "310 kHz - 32 MHz and 44-54 MHz..." > > I was looking forward to using the KX3 on the new 630m Ham Band > recently approved by WRC-2012: > 472-478 KHz. The K3 operates down to 490 KHz but no lower so > unusable on the new ham band. The KX3 "appeared" to be the first > commercially mfd radio able to operate down there. If not then this > is a BIG missed opportunity. > > I use a Clifton Labs Z-10020 MW BC Band Reject filter (540-1700 KHz) > which rejects signals inside that band. Signals seen at -50 dBm are > reduced to the the -110 dBm noise floor, whereas the signals below > 540-KHz are unaffected below about 515 KHz. I have used it with the > K3 and my SDR-IQ (which tunes to 500-Hz). > > There was discussion last fall that the KX3 might be capable of > transmitting on 630m. > I would like the official word on this before publishing my paper > reviewing the KX3 at MUD-2012. > > 630m will remain the province of the "experimenter" if no commercial > "shelf-ready" equipment is available. > > > 73, Ed - KL7UW > I run 100w into a 43x122 foot inverted-L on 600m under the license > WD2XSH/45. > ------------------ > Date: Sat, 7 Jul 2012 08:15:31 -0500 (GMT-05:00) > From: Mike Morrow <[hidden email]> > Subject: [Elecraft] KX3 Receive Performance Below 1500 kHz > To: [hidden email] > Message-ID: > <[hidden email] > > > > Content-Type: text/plain; charset=UTF-8 > > A discussion of KX3 MF lack of sensitivity recently took place > on the KX3 list. The KX3 should not be considered really > usable below about 1500 kHz, as Wayne explsined: > > ---- Original Message (from KX3 list) > >> I thought there was some advantage to AM BCB reception >> to be had with the KXAT3. > > If a KXAT3 is installed, harmonic images are attenuated, > but this has little effect on signal strength. > >> Why wouldn't the T/R PIN diodes be as well protected by >> high pass filtering that rolled off below 400 kHz rather >> than 1500 kHz > > The carrier lifetime of the diodes is roughly 1.5 microseconds. > This means that strong signals at the low end of the broadcast band > could cause IMD (IP2) if not attenuated. The HPF provides > about 20-30 dB of rolloff by this frequency, ensuring that > this isn't a problem. The KX3 is optimized for ham-band use > so this is entirely appropriate. > > Wayne > > > 73, Ed - KL7UW, WD2XSH/45 > ====================================== > BP40IQ 500 KHz - 10-GHz www.kl7uw.com > EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? > DUBUS Magazine USA Rep [hidden email] > "Kits made by KL7UW" http://www.kl7uw.com/kits.htm > ====================================== > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: KX3 Receive Performance Below 1500 kHz
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Wayne,
Thanks for the quick reply. I have also determined that there is reception down to 310-KHz when I use an antenna cut for 500-KHz. My first test was quick and used my 80m inverted-V which resulted in nothing being heard (maybe I did not have a good connection; it was just a quick look). I saw useful receive levels which would lead me to think use of my Clifton BC band reject filter ahead of a preamp tuned for 470-KHz would probably restore good sensitivity without subjecting the KX3 to overloading signals from the BC band (based on what I see using this filter with the K3 and the SDR-IQ). +10 dBm is quite sufficient for my transmit amplifier (a converted 100w NDB transmitter). I drive it with under 1mw direct from the K3 running in TEST mode output of the transverter output jack. I have built a low-pass filter for 510-KHz which can be used for transmitting (rated several hundred watts). WRC-12 stipulates ham output on the 630m band will not exceed 1w ERP (and no more than 5w ERP if permitted by certain national regulatory agencies). The ARRL Experimental Group was licensed to run up to ERP=20w; my 100w transmitter produces 4.15w ERP with my inverted-L antenna. So considering the low efficiency of antennas that hams would use one may only need something like 20w RF output. That is +43 dBm implying the need for about 30-dB transmit amplifier for the KX3. Relatively easy to do at this frequency (even a tube-type amp ckt drug out of an old 1960-70 manual would work). Some of our experimenters have had success converting stereo audio amplifiers into 500-KHz amplifiers with suitable change of input/output transformers and bypassing changes. Of course using a transverter is an option but that is a builder-experimenter option, at present. I actually built one for translating 10.4xx to 4xx KHz by use of a SBL-1 mixer and my 10-MHz OCXO station freq. reference source. The K3 will operate in test mode for running at 10.472-10.478 KHz. For other radios one would chose a ham band such as 80m or 40m to translate down. I will do some testing with my KX3 on transmitting at 470-KHz and have in mind a transistor amp to provide 25w (which I may eventually make if there is a market). Ham radio use of 472-478 KHz will require FCC action to happen in the USA. WRC-12 approves use after Jan 1, 2013. 73, Ed - KL7UW At 07:49 AM 7/8/2012, Wayne Burdick wrote: >Hi Ed, > >The KX3's spec also says, "Note: Sensitivity decreases gradually below >1.5 MHz due to protective high-pass filtering...." We did this to >ensure that the PIN diodes in the T/R switch are protected. A fairly >large amount of attenuation is required by the time you get down to >500 kHz or lower. > >We did do some transmit tests in the 470 kHz range. We can easily get >+10 or possibly +20 dBm output at these frequencies, but you'd need an >external filter/amplifier to obtain useful transmit power output. >Given that, I would think that an external receiving converter that >shifted the 0-1 MHz range up to 7-8 MHz on the KX3 would also be a >good solution. The KX3 has transverter bands that can be set up for >this application, allowing the VFO to read correctly when on this >band. The ACC2 GPIO pin could be used to turn the external converter >on/off. > >The K3 has the same high-pass filtering in the main antenna path as >the KX3. But the K3 also provides a way to bypass the filter, by using >the KXV3's RX ANT input (or the XVTR input). > >73, >Wayne >N6KR > > >On Jul 8, 2012, at 12:22 AM, Edward R. Cole wrote: > >>If this is true then the spec on page 51 of the KX3 manual is very >>misleading where is states: >>"310 kHz - 32 MHz and 44-54 MHz..." >> >>I was looking forward to using the KX3 on the new 630m Ham Band >>recently approved by WRC-2012: >>472-478 KHz. The K3 operates down to 490 KHz but no lower so >>unusable on the new ham band. The KX3 "appeared" to be the first >>commercially mfd radio able to operate down there. If not then this >>is a BIG missed opportunity. >> >>I use a Clifton Labs Z-10020 MW BC Band Reject filter (540-1700 KHz) >>which rejects signals inside that band. Signals seen at -50 dBm are >>reduced to the the -110 dBm noise floor, whereas the signals below >>540-KHz are unaffected below about 515 KHz. I have used it with the >>K3 and my SDR-IQ (which tunes to 500-Hz). >> >>There was discussion last fall that the KX3 might be capable of >>transmitting on 630m. >>I would like the official word on this before publishing my paper >>reviewing the KX3 at MUD-2012. >> >>630m will remain the province of the "experimenter" if no commercial >>"shelf-ready" equipment is available. >> >> >>73, Ed - KL7UW >>I run 100w into a 43x122 foot inverted-L on 600m under the license >>WD2XSH/45. >>------------------ >>Date: Sat, 7 Jul 2012 08:15:31 -0500 (GMT-05:00) >>From: Mike Morrow <[hidden email]> >>Subject: [Elecraft] KX3 Receive Performance Below 1500 kHz >>To: [hidden email] >>Message-ID: >> >><[hidden email] > >> >>Content-Type: text/plain; charset=UTF-8 >> >>A discussion of KX3 MF lack of sensitivity recently took place >>on the KX3 list. The KX3 should not be considered really >>usable below about 1500 kHz, as Wayne explsined: >> >>---- Original Message (from KX3 list) >> >>>I thought there was some advantage to AM BCB reception >>>to be had with the KXAT3. >> >>If a KXAT3 is installed, harmonic images are attenuated, >>but this has little effect on signal strength. >> >>>Why wouldn't the T/R PIN diodes be as well protected by >>>high pass filtering that rolled off below 400 kHz rather >>>than 1500 kHz >> >>The carrier lifetime of the diodes is roughly 1.5 microseconds. >>This means that strong signals at the low end of the broadcast band >>could cause IMD (IP2) if not attenuated. The HPF provides >>about 20-30 dB of rolloff by this frequency, ensuring that >>this isn't a problem. The KX3 is optimized for ham-band use >>so this is entirely appropriate. >> >>Wayne >> >> >>73, Ed - KL7UW, WD2XSH/45 >>====================================== >>BP40IQ 500 KHz - 10-GHz www.kl7uw.com >>EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? >>DUBUS Magazine USA Rep [hidden email] >>"Kits made by KL7UW" http://www.kl7uw.com/kits.htm >>====================================== >>______________________________________________________________ >>Elecraft mailing list >>Home: http://mailman.qth.net/mailman/listinfo/elecraft >>Help: http://mailman.qth.net/mmfaq.htm >>Post: mailto:[hidden email] >> >>This list hosted by: http://www.qsl.net >>Please help support this email list: http://www.qsl.net/donate.html 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep [hidden email] "Kits made by KL7UW" http://www.kl7uw.com/kits.htm ====================================== ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by wayne burdick
Wayne: An Elecraft Transverter for below 510 kHz would be well received, world wide. I guess the number of participants would be rather low to start with but interest would increase with the availability of such an item. A poll of the amateur market would give a good indication of interest. If the numbers aren't there to warrant such venture, then maybe one of the small kit-providers might pick up the banner. Presently, I see two potential customers; KL7UW and myself. How's that for a start? ;) 73 de Bill-w7kxb . . > From: [hidden email] > To: [hidden email] > Date: Sun, 8 Jul 2012 08:49:25 -0700 > CC: [hidden email] > Subject: Re: [Elecraft] KX3 Receive Performance Below 1500 kHz > > Hi Ed, > > The KX3's spec also says, "Note: Sensitivity decreases gradually below > 1.5 MHz due to protective high-pass filtering...." We did this to > ensure that the PIN diodes in the T/R switch are protected. A fairly > large amount of attenuation is required by the time you get down to > 500 kHz or lower. > > We did do some transmit tests in the 470 kHz range. We can easily get > +10 or possibly +20 dBm output at these frequencies, but you'd need an > external filter/amplifier to obtain useful transmit power output. > Given that, I would think that an external receiving converter that > shifted the 0-1 MHz range up to 7-8 MHz on the KX3 would also be a > good solution. The KX3 has transverter bands that can be set up for > this application, allowing the VFO to read correctly when on this > band. The ACC2 GPIO pin could be used to turn the external converter > on/off. > > The K3 has the same high-pass filtering in the main antenna path as > the KX3. But the K3 also provides a way to bypass the filter, by using > the KXV3's RX ANT input (or the XVTR input). > > 73, > Wayne > N6KR > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Not to rain on anyone's parade, Bill, but a couple of things
come to mind: -- I would think it a risky business to develop a transceiver for a band that is not yet authorized for amateur use -- If most of us have trouble getting an antenna going for 160m - wow - 630m? Just thinking out loud; not wanting to discourage anyone. 73 de Jim - AD6CW On 7/8/2012 10:42 AM, Bill Harris wrote: > Wayne: > An Elecraft Transverter for below 510 kHz would be well received, world wide. I guess the number of participants would be rather low to start with but interest would increase with the availability of such an item. A poll of the amateur market would give a good indication of interest. If the numbers aren't there to warrant such venture, then maybe one of the small kit-providers might pick up the banner. > Presently, I see two potential customers; KL7UW and myself. How's that for a start? ;) > 73 > de Bill-w7kxb > . . > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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There are plenty of LF converters to homebrew from, most very
simple including those using an SA602/612. Another is the AMRAD LF converter, QST April 2002. PCBs can be purchased from FAR circuits. I use three of those for dual RX and TX with a 14MHz local oscillator and a K3 in transverter mode, displaying the actual LF freq (Project: http://no3m.net/index.php?page=600m ). There are guys in the experimental group running antennas far smaller than most would consider. However, while a short, minimally top-loaded (relatively speaking), heavily base loaded antenna will be grossly inefficient, all it takes is more power to reach the ERP level, which will be low anyways. 73 - Eric NO3M On 07/08/12 18:48, Jim Lowman wrote: > Not to rain on anyone's parade, Bill, but a couple of things > come to mind: > > -- I would think it a risky business to develop a transceiver > for a band that is not yet authorized for amateur use > > -- If most of us have trouble getting an antenna going for > 160m - wow - 630m? > > Just thinking out loud; not wanting to discourage anyone. > > 73 de Jim - AD6CW > > On 7/8/2012 10:42 AM, Bill Harris wrote: >> Wayne: >> An Elecraft Transverter for below 510 kHz would be well received, world wide. I guess the number of participants would be rather low to start with but interest would increase with the availability of such an item. A poll of the amateur market would give a good indication of interest. If the numbers aren't there to warrant such venture, then maybe one of the small kit-providers might pick up the banner. >> Presently, I see two potential customers; KL7UW and myself. How's that for a start? ;) >> 73 >> de Bill-w7kxb >> . . >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by KXBill
Jim,
Actually WRC-12 authorized ham radio use world-wide (with a few countries excluding themselves) starting on 1Jan2013. True that the FCC has not yet put into affect rules to allow it in the USA. I think it will happen in 2013! Its risky business to build radios for QRP but Elecraft did. The KX3 is a risk until several hundred orders came in! IBM did not take a risk so in 1977 a couple teenagers in their garage built the Apple and now the only things we read about are i-phones, i-pods, i-pads...and where is i-bm? Detroit did not take a risk so in the 1970 gasoline crises several Asian auto makers captured the small car field throwing GM into a head-spin downward for a decade trying to catch up. Typically, if you wait for a market to mature you are left in the dust of others. You can be sure there are several innovators looking at the potential of the new 630m ham band. Don't worry about discouraging them! I think the KX3 still has promise of being a good 630m radio (with a little help from its friends). 630m will likely be slow to start (just like the 60m band), but in time there will be a decent population there. Right now it is still an experimental band. Antennas are small for the wavelength but even with 4w ERP my signal was copied 2893mi distant. Antenna is about the same size as one for 160m (43x122 foot inverted-L). Ground-wave propagation to 300-km appears to be rock-solid (all the time). My signals were received at 91mi at 35-dB over noise for months with barely a couple dB variation in strength. Terrific emcomm potential. Why the ships used it for their emergency band when CW was still in use. 73, Ed ------------------------------- Date: Sun, 08 Jul 2012 15:48:18 -0700 From: Jim Lowman <[hidden email]> Subject: Re: [Elecraft] K3/KX3 MF/LF Transverter To: [hidden email] Message-ID: <[hidden email]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Not to rain on anyone's parade, Bill, but a couple of things come to mind: -- I would think it a risky business to develop a transceiver for a band that is not yet authorized for amateur use -- If most of us have trouble getting an antenna going for 160m - wow - 630m? Just thinking out loud; not wanting to discourage anyone. 73 de Jim - AD6CW 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep [hidden email] "Kits made by KL7UW" http://www.kl7uw.com/kits.htm ====================================== ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Ed: The close in coverage 630m offers, 24/7, is exactly why the interest among our local Emcomm folks. It will work out extremely well for those in Alaska. Someone is sure to ask; Will the KPA500 go down that low ? I imagine with a little tweaking, here and there, it can. de Bill-w7kxb . . > Date: Tue, 10 Jul 2012 00:13:28 -0800 > To: [hidden email] > From: [hidden email] > Subject: Re: [Elecraft] K3/KX3 MF/LF Transverter > > Jim, > > Actually WRC-12 authorized ham radio use world-wide (with a few > countries excluding themselves) starting on 1Jan2013. True that the > FCC has not yet put into affect rules to allow it in the USA. I > think it will happen in 2013! > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K3/KPA500/KX3 630 meters
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Sure, I can see the EMCOMM shack on the belt types with their mobile "high efficiency" 630 meter antennas now! Anyone calculate the battery requirements for 5W ERP with even a 16' whip? 200 miles will not even cover Florida from Tallahassee to Miami ... I can't imagine a use for 630 meters other than as a curiosity. It is a shame that ARRL and IARU wasted all of the political capital on 630 meters rather than securing an worldwide exclusive 50 - 100 KHz wide allocation somewhere useful like 60 meters. 73, ... Joe, W4TV On 7/10/2012 2:37 PM, Bill Harris wrote: > > Ed: > The close in coverage 630m offers, 24/7, is exactly why the interest among our local Emcomm folks. It will work out extremely well for those in Alaska. > Someone is sure to ask; Will the KPA500 go down that low ? I imagine with a little tweaking, here and there, it can. > > > de Bill-w7kxb > . . >> Date: Tue, 10 Jul 2012 00:13:28 -0800 >> To: [hidden email] >> From: [hidden email] >> Subject: Re: [Elecraft] K3/KX3 MF/LF Transverter >> >> Jim, >> >> Actually WRC-12 authorized ham radio use world-wide (with a few >> countries excluding themselves) starting on 1Jan2013. True that the >> FCC has not yet put into affect rules to allow it in the USA. I >> think it will happen in 2013! >> > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Edward R Cole
As one who has been exploring caves for the last 40+ years, my
principle interest in the 630M band is its ability to communicate thru solid rock. There is a long history of cave radios operating on medium frequencies under part 15, most of which use antennas consisting of a coil of wire. (One of the rules of thumb for cave radios is that the antenna and the battery should weigh about the same.) Cave radios used for communication are quite different from those used to locate the surface point directly over an under-ground point, and estimate its depth. If you are interested in cave radios, most of the work in the US has been documented in Speleonics, published by the Communication and Electronics Section of the National Speleological Society. All issues are available for free download from <http://www.caves.org/section/commelect/drupal/speleonics>. The most recent issue has an index of all issues and is available from <http://www.caves.org/section/commelect/splncs/splncs28.pdf>. There is also an active British group, the Cave Radio and Electronics Group <http://bcra.org.uk/creg/>. They accept Paypal for their publications. Cheers - Bill, AE6JV On 7/10/12 at 1:13, [hidden email] (Edward R. Cole) wrote: >I think the KX3 still has promise of being a good 630m radio >(with a little help from its friends). 630m will likely be >slow to start (just like the 60m band), but in time there will >be a decent population there. Right now it is still an >experimental band. ----------------------------------------------------------------------- Bill Frantz | gets() remains as a monument | Periwinkle (408)356-8506 | to C's continuing support of | 16345 Englewood Ave www.pwpconsult.com | buffer overruns. | Los Gatos, CA 95032 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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