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 <k...@earthlink.net> > Subject: [Elecraft] KX3 Receive Performance Below 1500 kHz > To: elecraft@mailman.qth.net > Message-ID: > > <24244062.1341666931975.javamail.r...@mswamui-swiss.atl.sa.earthlink.net > > > > 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 dubus...@gmail.com > "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: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
