KX3-2M module?
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OK, there has been a lot speculation but nobody has one yet to test.
I both run JT65 on eme and WSPR on VHF and 600 meters, so I am fairly experienced in using these modes. I plan to rigorously test the KX3 + 2M for specs and test running these modes with real eme signals. I can run my K3 + 2m transverter (from another mfr) in parallel to compare performance receiving signals. I will test the frequency drift transmitting 3w. I have a EIP-538 mw frequency counter good to 26-GHz which uses an internal TCXO or external 10-MHz reference. I have a Rubidium reference oscillator with short-term stability of +/- 5 E-11 (that is 0.0000000005 or 0.0005 ppm) to use as reference source. That will definitely measure the frequency accuracy and stability of the KX3 + 2M combination. I do not have a set up for measuring phase noise, but the parallel test described above will compare sensitivity using my K3 with TCXO-3/EXREF using an OCXO reference (be my phase noise reference). The OCXO is +/- 5 E-12 with Phase noise = -86 dBc/Hz, -118 dBc/Hz (100-Hz), -119 dBc/Hz (1KHz). I will publish my testing results on my website (I'll post the link when this is done). I also operate microwaves up to 10-GHz: currently have 1296-28, 3400-144, and 10,368-144 MHz transverters. All operate with an LO frequency about 1100-MHz and multiply to the frequency needed to mix with the IF radio. Example: the 10,368 MHz transverter uses an xtal LO = 189.33 MHz which is multiplied to 10,224 MHz and mixes with 144-MHz from the IF radio. the stability of the 189.33 MHz xtal oscillator is multiplied x54 and added to that of the 144-MHz radio. It should be obvious that the stability of the transverter LO is way more important since it gets multiplied. More and more PLL LO's are being used for this so the resulting LO frequency of 10,224 MHz is < +/- 9-Hz. At worst case this is added to the +/- 10-Hz of the KX3+2M to provide a frequency error of up to 19-Hz. Wow! I think folks need to settle down and wait a bit until we can provide some independent testing before judging the merits of the KX3+2M. 73, Ed - KL7UW ------------- Date: Tue, 8 Apr 2014 17:08:29 -0700 From: Wayne Burdick <[hidden email]> To: Walter Underwood <[hidden email]> Cc: "[hidden email] Reflector" <[hidden email]> Subject: Re: [Elecraft] KX3-2M module? Message-ID: <[hidden email]> Content-Type: text/plain; charset=iso-8859-1 Actually, with extended temp compensation applied, the KX3-2M module's long-term frequency stability is typically better than +/- 0.1 ppm (+/- 10 Hz). But it's the short-term excursions within this range that would probably not work with JT65. Again, I haven't tried it. These excursions are due to the FLL (frequency-locked-loop) algorithm, which obtains data from an EEPROM table having increments of about 0.1 degree C (after calibration is complete). 73, Wayne N6KR 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
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In reply to this post by Stewart Bryant
I wouldn't be doing that for a couple reasons Stewart. I was advised not to by Elecraft in previous discussions.
1.Wideband transmitted Noise. Under driving the radio PA stageswhile they still have the same gain means that the S/N of the transmitted signal is reduced considerably, a bad thing especially if a high power amplifier is planned on the VHF and above bands where band noise is low and transmitter wideband noise will be heard over a wide area. 2. There are some gotchas with the KX3 and setting the output to a low value in the transverter menus. I have mentioned these before, but the ATU Tune button is dangerous as it will put out a lot more power than what is set in the transverter power setting in the settings! Danger Will Robinson! So, the only sensible and safe way to wire into an external transverter is to use normal HF power output and attenuate with a power attenuator it before the input of the transverter, wasteful in power and heat, but... So aftermarket KX3 PA heatsink and copper heatspreader for SI570 and extra calibration for VFO temperature may be essential for the highest frequency stability. 73 David Anderson GM4JJJ > On 9 Apr 2014, at 08:24, "[hidden email]" <[hidden email]> wrote: > > When driving a transverter presumably you will be running at 0dbm rather than at 5W. I wonder if the KX3 still experience thermal drift due to PA heating at very low power? > > Stewart/G3YSX > Sent from my iPad > > ______________________________________________________________ > 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 > Message delivered to [hidden email] 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 Message delivered to [hidden email] |
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In reply to this post by W7GJ, Lance
Stewart,
That's a good question. Certainly lower RF output will generate less heat. One issue that would need to be determined is whether the 2M module has any operating mode which would result in a full output spike which would likely destroy 0 dBm input circuit components. This has been documented for many non-Elecraft radios. But let's assume you can turn power to 0.1w at minimum (that is currently indicated on the KX3 PWR control). That would be 100mw or +20 dBm level. That can be attenuated to 0 dBm using a chip 50-ohm load or 20-dB attenuator (which I would be sure was rated for 3w - just in case). Design of transverter IF connections could either be common Rx/Tx or separate (preferred). If common, the transverter will have some sort of IF T/R control so load/atten. could be inserted on the Tx side. Inserting 20-dB attenuation on receive would affect receive sensitivity and possibly system NF. The circuit using a 50-ohm load would couple low power via a 10pF capacitor. You might need to have an adjustable drive level pot following this (make it an L-pad). With operation at this level frequency drift characteristics will likely by the same for Rx and Tx. I can test this concept when I get the 2M module for testing on my bench. 73, Ed - KL7UW ------------------ Date: Wed, 9 Apr 2014 08:24:57 +0100 From: "[hidden email]" <[hidden email]> To: Dave <[hidden email]> Cc: "<[hidden email]>" <[hidden email]> Subject: Re: [Elecraft] KX3-2M module? Message-ID: <[hidden email]> Content-Type: text/plain; charset=us-ascii When driving a transverter presumably you will be running at 0dbm rather than at 5W. I wonder if the KX3 still experience thermal drift due to PA heating at very low power? Stewart/G3YSX Sent from my iPad 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: [hidden email] ______________________________________________________________ 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 Message delivered to [hidden email] |
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