Re: [Elecraft] FTDX5000 Design Flaw
The ARRL is aware of this issue. This problem was discussed in my 1988 articles on phase noise in QST (March April issues). The article notes that a high phase noise transmitter degrades the performance of a low phase noise receiver to that of the transmitter. This article started the ARRL making composite transmit noise measurements. A strong signal (S9+50dB) from a transmitter with broadband -130 dBc composite noise in a 500 Hz bandwidth reduces the receiver's blocking dynamic range to 103 dB. Most top notch receivers show a blocking dynamic range of around 140 dB. In this case, the dynamic range is reduced because the noise floor is increased. I don't think most hams are aware of the problem. If you have a nearby ham running high power and your receiver doesn't work well when they are transmitting, you just assume that the signal is too strong for your receiver. This problem is like splatter or key clicks. It doesn't impact the owner of the transmitter, but instead degrades the receiving environment of those who live near them. There is little incentive for the owner of the high composite noise transmitter to improve their equipment. -John KI6WX The FTDX500 wouldn't be the only one, if a -130 dBc composite noise number defines failure. If you have access to QST reviews, compare: Flex 5000 FT-2000 Orion II IC-7700 K3 all of which plot tx composite noise at 100 or 200 W out to 1 Mhz. You can draw your own conclusions, but the FTDX5000 apparently isn't exceptional in that regard. The Flex is no better than -120 dBc out to 1 MHz, the FT-2000 is slightly worse than the FTDX-5000, and the Orion II is no better than -130 dBc out to 100 kHz. The Icom rigs seem to do a little better. The K3 performance indeed far surpasses the others. I could find no comment on these numbers in the reviews. Bob NW8L Why is this not sent to the Editor and Technical Editor or QST as well as the lead test engineer at the ARRL lab? What was their response? If the radio's transmitted phase noise is that bad, Yaesu should be forced to recall all units currently in the field. 73, ... Joe, W4TV __ 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] FTDX5000 Design Flaw
There have been a lot of comments on the reflector about the QST review of the FTDX5000. However, no one has noted a significant design flaw in the transmitter that shows up in the review. Refer to Figure 3 that shows the composite transmitter noise. It shows a noise level of -130 dBc/Hz from 10 kHz to 1 MHz (and probably beyond). This transmitter when combined with a full power amp could wipe weak signals in an entire amateur band for anyone living within a few miles of the transmitter (see the math calculation below). While a number of other transceivers have this problem, I wouldn't expect a top of the line $6K radio to have such lousy composite transmit noise. This problem is created either in the radio's synthesizer or its transmit amplification chain. The K3 was specifically designed to minimize composite transmit noise. The K3 QST review showed a transmit noise level of -155 dBc/Hz at a 100 kHz offset. This is 4 S-units less noise than the FTDX5000 at the same offset. This is not a theoretical calculation. I know of one case of composite transmit noise where an amateur transmitter wiped out weak signal reception across an entire ham band in a receiver located several miles away. -John KI6WX CALCULATIONS Assume that we have a FTDX5000 transmitting CW on 20 meters followed by a 1.5 kW amp. The transmit power is +62 dBm. At a 100 kHz offset, the transmit noise is -68 dBm/Hz. Assume that the FTDX5000 transmit output is fed to an isotropic radiator (0 dB gain) on top of a hill and we have a receiver also with an isotropic antenna in a valley with line of sight to the hill. For directional antennas, the sum of the antenna gains depends on where they are aimed and could be greater or less than the 0 dB in this example. For the moment, we'll place the receiver 1 mile from the transmit antenna. The path loss between the transmit and receive antennas is 60 dB, which implies the receive power of the transmit noise will be -128 dBm/Hz. The normal atmospheric noise on 20 meters is about -144 dBm/Hz, which means that the transmit noise will be 16 dB greater than the normal background noise. This noise will be spread across the entire band whenever the FTDX5000 is transmitting. If it is transmitting CW, the receiver will hear noise modulated in Morse code. If it is transmitting SSB, the noise will vary with the voice modulation peaks. The receiver would have to be more than 6 miles away for the noise to drop to background levels. Another way to look at this problem is how many S-units would the show up in a 500 Hz receive bandwidth. The total power in the noise is -101 dBm in the 500 Hz bandwidth. S4 is -103 dBm, so the noise would be about a S4 signal level. Each time you halve the distance to the transmitter, the noise will increase by 1 S-unit. If you live 1000' from a FTDX5000, you could see a noise level of S7. You can reduce the noise by using a narrower filter, but you would have to drop down to a 100 Hz filter to reduce it by 1 S-unit. This calculation was done with the transmit antenna on top of a hill so we could use free space radiation to calculate the path loss. If both antennas are on a flat surface of earth, the path loss will be somewhat greater, but the exact magnitude requires using antenna radiation software such as NEC-4. __ 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] 250 Hz and 400 Hz Filter Measurements
Beware of the conclusions of the so-called K3 Filter Study. I don't know who wrote it since there is no name on it, but the 250 Hz filter does not fall apart at -25 dB. The results shown are exactly what you would expect for a well-designed receiver with no signal at the input. The author of this study doesn't state the conditions of the K3 such as band, preamp status and antenna connection, but I will assume no antenna connected with the preamp on. If you look at the first plot on page 3 labeled Study of Inrad 400 and 250 Hz Filters, you will see a broad shoulder at about 30 dB down that the author is concerned about. This shoulder drops off at 100 Hz and 1100 Hz due to the DSP filtering. So let's look at what is causing this. There is no signal into the K3, so all of the noise is internally generated. At 600 Hz, the noise is coming from the preamp and is then filtered by the 250 Hz and 400 Hz roofing filters. The shoulder is caused by the internally generated noise after the roofing filter. The noise from the preamp is dominate, so that is sets the noise figure. However, if we made it even more dominate, so that the shoulder was lower, we would reduce the dynamic range of the K3. Receiver design is a tradeoff so that you create both minimum noise and maximum dynamic range. If the author had coupled a noise diode to the input of this K3, he would have found that the shoulder would disappear because he now had a noise signal into the K3 much stronger than the preamp. My advice would be to disregard this report because the measurements were not made in such a way as to accurately determine the response of the K3 filters. -John KI6WX Both you and Ed raise good points. No intent there -- I agree that the so-called 250 Hz filter is slightly more useful than the 400 Hz. My real objective is to get Inrad to clean up their act! BUT -- take a look at the data in this link. Lots of food for thought. There's something different about the K3 Sub-RX, and the Roofing filters seem to fall apart below about -25dB. Makes a guy wonder what's going on! http://audiosystemsgroup.com/K3FilterStudy-250HzRoof.pdf 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] Has anyone epoxied their toroids after they were wound?
Applying any material (Q-dope, epoxy, hot glue) to the wound toroid is not a good idea. It increases the interwinding capacitance and can effect the performance of the various toroidal transformers. This is especially true in the transmitter section where the toroids are tuned with a fixed capacitor to increase the power transfer. The value of these capacitors was determined without any coating material on the toroid, and changing the dielectric around the toroid windings may require a change in the capacitor's value. -John KI6WX Never have epoxied toroids, I can see one major disadvantage using this method... You'd never be able to rewind the same core. Epoxy is a real bear to remove. I've used hot glue to keep toroids in place, a little easier to remove if needed. Think you're better off with nail polish or acrylic.. ___ 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
Re: [Elecraft] K3 roofing filter group delay
Don; Don't forget Bessel filters. These are maximally flat for group delay, but have a much slower rolloff. A 5-pole 500-Hz 0.5 dB Chebyshev will be down 80 dB at 1 kHz and will have a group delay of 16 ms at band center and 44 ms at -3 dB. A 5-pole 500-Hz Bessel filter will be down 40 dB at 1 kHz and have a constant group delay across the passband of 10 ms. You can have a flat group delay or a fast rolloff, but you can't have both. -John KI6WX Brian and all, The number of poles is not the primary deciding factor. It is the type of filter (Cohn, Chebychev, Butterworth, Gaussian to 6 dB, Gaussian to 12 dB, etc.) that will influence the group delay. See the discussion on filters in Experimental Methods for RF Design for further information. In general, those filters with a 'rounded nose' will have the best group delay characteristics - but that is only a generalization, the details will tell the rest of the story. 73, Don W3FPR Brian Lloyd wrote: A number of messages have gone back and forth here about roofing filters. We did mention group delay but I wonder if Elecraft can provide group delay characteristics for the various filters offered for the K3. Seems to me that, in general, fewer poles tend to provide better group delay in a filter at the expense of the skirts. OTOH, if the skirts in the roofing filter are sufficient to attenuate a strong, undesired signal so that it cannot cause desense, then it strikes me that the 5-pole filters might actually provide superior performance for digital communications. 73 de Brian, WB6RQN Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com ___ 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
Re: [Elecraft] K3 roofing filter group delay
You can cascade a pair of Bessel filters to get better frequency response while maintaining a flat group delay, but you do have to isolate them so that they both are seeing a resistive source and load impedance. The cascaded filters would show a 6 dB rolloff at nominal cutoff frequency. The 3 dB point will occur at about 70% of bandwidth. A pair of 5-pole Bessel filters cascaded with a 500 Hz 3 dB bandwidth will be down about 55 dB at 1 kHz. The better method is to build a 10-pole 500-Hz Bessel filter which will be down nearly 60 dB at 1 kHz. There was also a question about a linear phase filter with equiripple error. A 0.5 degree error is about +/-5% variation in group delay. A 5-pole 500-Hz 0.5 degree equiripple filter will be down 50 dB at 1 kHz and have about 11 ms of group delay. -John KI6WX Don't forget Bessel filters. These are maximally flat for group delay, but have a much slower rolloff. John, What penalty (if any) would occur in cascading identical Bessel filters to improve roll-off and stop-band attenuation? Would the overall response still be considered Bessel, or will a point be reached where the response begins to take on Chebyshev characteristics? ___ 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
Re: [Elecraft] K3 TX IMD
Craig; I can't comment specifically on the TX IMD performance since I wasn't involved with that part of the design. The comments I made referred to excessive broadband amplitude and phase noise that some transmitters generate that can cover 100's of kHz of bandwidth. If you live near such a transmitter running a kW of power, you can hear the transmissions across much of an amateur band. We do understand that problem and worked to minimize it as much as we reasonably could. -John KI6WX I was intrigued by Johns KI6WX comments on the K3's transmitter design. Quote The K3 is designed to not only receive signals in a noisy RF environment, but also to generate a much cleaner signal in transmit How good is the transmitter IMD performance? I was also wondering if the issue of TX ALC induced IMD was addressed? A problem thats so common in many Japanese radios. Would the K3 meet the NTIA Redbook Standard? I was also wondering what final PA transistors or FET's are used in the K3? Craig VK3HE ___ 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
Re: [Elecraft] Now for the real question about the K3!
OK Here is the real question. How did you keep the K3 a secret? Lots of guys working on the K3 project plus the testers. How did you keep the secret? We made sure no one in the group has ever held, nor is known to want to hold, public office. 73, Lyle KK7P And Wayne kept everyone real busy looking at design issues, plus some of us also hold real jobs during the daytime, so no time to write blogs on Elecraft development projects. Both Lyle and I quit doing K2 mods several years ago as the K3 design effort heated up, so maybe that was the best clue that something was going on. -John KI6WX ___ 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
Re: [Elecraft] YAQ: K3
Toby; The phase noise of the K3 is significantly less than the K2. One of our main design goals was to improve the local oscillator design of the K3 without adding significant cost to the radio. After much design work and experimental tests, we were able to find a unique design that did this. The TCXO option has no effect on phase noise, only on the long term frequency stability of the radio. -John KI6WX YAQ: What are the phase noise figures like? Does the 1 PPM TCXO option improve them, and if so by how much? vy 73 de toby ___ 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
Re: [Elecraft] Fw: [bcc] Fw: Announcing the Elecraft K3 Transceiver:10/100W, 160-6m, Assembled or Kit
Toby; Wayne will have to answer whether Elecraft will be doing the work required to apply a CE mark. I am not sure it is required since the K3 is powered off of 12 volts. The K3 will meet all RoHS requirements. -John KI6WX He wants to know if the K3 has or will have a CE sticker. Otherwise he is worried that customs hier in Germany might not let the K3 in. This has never been a problem with any amateur stuff I have imported, which for the most part have kits, so he might have a point as far as the assembled version is concerned. ___ 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
Re: [Elecraft] The New K 3 kit
Official link should be up Monday. For the time being you can access the important data at: http://www.elecraft.com/K3 -John KI6WX So is there a link to see the new kit? I went to the Elecraft site and nothing about the K3 there?? Enquiring minds want to know ... :} Mike Heit KD7YLA ___ 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
Re: [Elecraft] K3 RX performance (tantalizing preview)
Let me add my 2 cents on this. We intentionally designed the K3 to minimize interference from nearby strong signals. This is done by optimizing the mixer and post amp to have high dynamic range and designing the local oscillator to have minimal phase noise. We wanted you to be able to copy that weak DX signal without interference at the same time your neighbor is running a K3 at a kilowatt output in the same part of the band. The K3 is designed to not only receive signals in a noisy RF environment, but also to generate a much cleaner signal in transmit. Some other rigs will generate broadband amplitude and phase noise when transmitting; we minimized that as much as possible in the K3 design. -John KI6WX Bill, W5WVO wrote: Have you yet published on this list or elsewhere any claimed RX bench metrics like noise floor, DR3, IP3, etc.? Not yet. We're still testing the beta units. But just to give you a hint: a couple of days ago Eric measured a blocking dynamic range of 143 dB, and it remained 143 dB at 20 kHz, 5 kHz, and 2 kHz. To put this into perspective, the K2, IC-7800, Orion II, and FTDX9000 all have a blocking dynamic range of -133 to -135. We can't directly extrapolate to IMDDR3, but suffice to say it will be excellent. 73, Wayne N6KR ___ 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
Re: [Elecraft] Characteristic Impedances
Which filters are you referring to? If it is the K2, clearly the BPF's are 50 ohms in and out. It is not so clear about the LPF. It could be doing some impedance transformation to match the output impedance of the amplifier on different bands. -John KI6WX Gang- Can anyone tell me the design values for the termination impedances for both the bandpass and lowpass circuits. I'd be ever so happy if it is 50 Ohms. Thanks, Bill NA7Y ___ 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
Re: [Elecraft] swr bridge diodes
Use a 1N5711. Breakdown voltage is 70 volts and voltage drop across the diode is only a few tenths of a volt at low current. It makes a reasonable detector up to 500 MHz. -John KI6WX Anyone have any idea what sort of diodes would work best in the swr bridge of a high power antenna tuner? What is normally used, fast switching or what? ___ 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
Re: [Elecraft] K2 fails PLL Reference Oscillator range test
Does the DC voltage change at pin 1 of U6? If yes, the problem is getting the voltage to the varactors or with the varactors. If no, the problem is with the DC circuitry around U6 or U5. Once you know the voltage for Band+/Band-, the problem should be fairly easy to track. -John KI6WX Hi guys, I'm on page 60 and had been having a heck of a time getting the 4MHz Oscillator calibration in spec. Got it in spec (12110.84), and proceeded to the PLL Reference Oscillator range test. Pushing Band+ and Band- yielded a change of a few Hz, but nothing approaching the required range of 9.8kHz - 15 kHz. I have already checked every component going line by line through the manual, all soldering has been checked about 10 or 20 times by this point (in the process of getting the 4MHz oscillator into spec). Q19 was replaced, and X1 also. At this point, I have to wonder if it's one of the ICs in the PLL section. This has been frustrating me for a couple of months now. ___ 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
Re: [Elecraft] K2 frequencyh stability
I believe the N1KO data was that he observed a drift of 80 Hz, not 800 Hz. A drift that large would indicate something seriously wrong in one of the oscillators. The current K2 design is not as good as a TCXO, but it is a lot better than an unstabilized crystal oscillator. It should be possible to reduce the drift to significantly less than 100 Hz over a temperature range of 10-50C with adjustment of resistor RA in the temperature compensation circuit. -John KI6WX - Original Message - From: VR2BrettGraham [EMAIL PROTECTED] For a point of reference for N1KO's observed 800 cycle drift as his K2 warms up with use, I looked up the specs for one of my non-TCXOd radios (IC-765) overall the radio can drift +/- 350 cycles from 0 to 50C after 1 minute from switch on, +/- 200 cycles in the first hour. ___ 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
Re: [Elecraft] K2 frequency drift
The K2 drift mentioned by Adam is about 5 ppm for 10 MHz WWV. This isn't bad for a non-TCXO oscillator. With TCXO oscillators, you can probably get down to 1 ppm, but it might cost you $50 extra. You can do even better by mounting the oscillator in an oven (OCXO), but it will cost you a penalty in both cost and power consumption. Neither of these options is feasible for the K2 design. Now a few comments about some of the other comments on this thread. The PLL reference is the major source of drift in the K2, especially on the higher frequency bands. If you reduce the PLL reference drift enough, you might find that the BFO drift becomes more significant. You can measure BFO versus PLL reference drift by measuring the frequency on both USB and LSB. The thermistor/resistor network for PLL reference frequency stabilization was designed to compensate both for warmup drift and drift induced by a KPA100. In receive only, the K2 internal temperature will rise about 10F in a half-hour. Running a KPA100 at high power can result in even larger temperature excursions. Adjusting RA can reduce this drift; just follow the instructions in the manual. Finally, the PLL reference frequency stabilization was tested in an temperature chamber from 40F to 120F, and the stabilization works well over this temperature range. In one test, the K2/100 was started cold at 59F for 30 minutes, and then put in transmit at 20 watts CW output for 40 minutes. This increased the internal temperature to 114F. The total VFO drift over this temperature range was 70 Hz; the total BFO drift was 10 Hz. The test unit has an optimized RA resistor. -John KI6WX - Original Message - From: [EMAIL PROTECTED] That being said, I still do notice a temperature-dependent frequency drift during normal usage. The drift is predictable, with the zero beat on the dial I get with reference to WWV drifting by as much as 70-80 Hz if the temperature difference between ambient and the max temp the rig hits with the KPA100 under heavy use is large. The frequency at which I can zero-beat WWV does not change unpredictably. The radio consistently zero-beats low (e.g. WWV zero-beats at 10.000.07) when cold. Is this a really big deal? On SSB, certainly not. On CW I like to zero-beat dead-on with the narrow filters. Perhaps I'm just being a perfectionist. ___ 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
Re: [Elecraft] QRP from the bottom of the Grand Canyon
Mike; In the 1970's, W6JTH and myself took a HW-7 into the bottom of the Grand Canyon in the area of Deer Creek and Thunder River/Tapeats Creek. We were able to work some stations on 40 meters, all within a few hundred miles of the canyon. We were not able to make any contacts on 20 or 15 meters. -John KI6WX - Original Message - From: Mike and Alicia Fanning [EMAIL PROTECTED] Anyone have any experience trying QRP from the bottom of the big hole? I will be backpacking the week of September 6-12 in the Grand Canyon, and would like to take my KX-1, but I don't want the weight if I will just be talking to myself. Anyone have any experience from the bottom of the Canyon (specifically at the sunspot pits or at Bright Angel campground)? Thanks, Mike, K4GU ___ 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
Re: [Elecraft] Unique synthesizer LO ?
Two additions to my recent posting based on several replies. The ARRL composite transmit noise test measurements have been 7.5 dB lower than reality for many years. This is true for all radios, not just the K2. My comment about improving the phase noise only applies if the RF board is re-designed. I don't think it is possible to significantly reduce the phase noise with a mod on the current board. -John KI6WX Peter; I have posted on the web a detailed set of measurements of the K2 phase noise, both in receive and transmit. The measurements cover a frequency range of 20 Hz to 45 kHz. These measurements can be viewed at: http://home.pacbell.net/johngreb/k2phasenoise.pdf The ARRL composite transmit noise measurements that were published in QST are in errror and show less noise than reality. The transmit phase noise measurements in the above document are the correct phase noise measurements, but they do not include any amplitude noise that might be on the transmit carrier. The K2 oscillator phase noise is good for a simple low-current synthesizer, but there are ways to make it better. I note some of those in the above document. A re-designed K2 RF board could drop the phase noise by at least 10 dB, which would improve the 5 kHz two-tone third-order dynamic range 6 dB. -John KI6WX Maybe not the cleverest question of the year but I cannot resolve this one myself and I'm eager to understand. It is said that the synthesized LO of the K2 is of a unique design. Though, when I compare the LO phase noise specs of the K2 and the AOR7030, the latter seems to show much better specs. What makes the K2 synthesizer so special ? I'd appreciate any comment. Peter, PE1E ___ 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 ___ 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
Re: [Elecraft] Unique synthesizer LO ?
Peter; I have posted on the web a detailed set of measurements of the K2 phase noise, both in receive and transmit. The measurements cover a frequency range of 20 Hz to 45 kHz. These measurements can be viewed at: http://home.pacbell.net/johngreb/k2phasenoise.pdf The ARRL composite transmit noise measurements that were published in QST are in errror and show less noise than reality. The transmit phase noise measurements in the above document are the correct phase noise measurements, but they do not include any amplitude noise that might be on the transmit carrier. The K2 oscillator phase noise is good for a simple low-current synthesizer, but there are ways to make it better. I note some of those in the above document. A re-designed K2 RF board could drop the phase noise by at least 10 dB, which would improve the 5 kHz two-tone third-order dynamic range 6 dB. -John KI6WX Maybe not the cleverest question of the year but I cannot resolve this one myself and I'm eager to understand. It is said that the synthesized LO of the K2 is of a unique design. Though, when I compare the LO phase noise specs of the K2 and the AOR7030, the latter seems to show much better specs. What makes the K2 synthesizer so special ? I'd appreciate any comment. Peter, PE1E ___ 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
Re: [Elecraft] KSB2 in K2/100
I know this message is a bit old, but I've been too tied up with other projects to read the reflector mail for the last two months (fyi - the reflector generated over 2000 emails in the last 2 months). The increased gain mod I did for the KSB2 was originally designed to increase the transmit gain in SSB for a barefoot K2. The original K2 had difficulty reaching 10 watts of power output in SSB on 10 meters. When you drove the audio input harder to get to full power, the K2 would start to clip on the audio peaks. This does not create a wider bandwidth signal because the SSB modulator is followed by the SSB filter, but it does increase the audio distortion. I added the extra emitter follower stage to increase the overall IF gain in the SSB transmit signal path. This mod should not be necessary with the KPA100, since it can reach full power with only a few watts of drive. Some folks have reported that the emitter follower stage can cause power output instability when the KPA100 is installed. There is at least one fix around that reduces the gain of the emitter follower stage by increasing the emitter resistor value and apparently eliminates this instability. I would recommend that the emitter follower gain stage not be used in a K2/100 since it does appear to cause a stability problem, and there is no need for the extra gain on 10 meters. -John KI6WX - Original Message - From: Roy Morris [EMAIL PROTECTED] Sent: Saturday, June 03, 2006 9:41 AM I would like to hear from anyone who has K2/100s with both the unmodified KSB2 and the modified KSB2 with the KI6WX 2N amp mod (and 1.08 firmware). How does this mod affect mic gain and VOX operation? How does the absence of this mod affect mic gain and VOX operation? Does the mod help SSB modulation on 10 meters with the power level set at 5 watts? Do you find this mod helpful at 100 watts? Thanks for your input. Roy Morris W4WFB ___ 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
Re: [Elecraft] K2 frequency drift
Dave; I designed the K2 VFO stability mod that is now included in all K2's. Variations in the crystal stability cause each K2 to drift slightly differently. That's why I included the instructions on how to adjust the resistor values to minimize the K2's drift. I tested my K2 from 15C to 45C in a home built environmental chamber (use one of those thermoelectric cooler/heaters from WalMart or Target). I picked the resistor values to produce the minimum drift over an assortment of crystals that Elecraft sent me. I also adjusted those resistor values to achieve minimum drift in my K2. Over that temperature range, my K2 shows a maximum drift rate on its worst case band of 15m of 1.8 Hz/C. The average drift rate is less than 1 Hz/C. The K2 warmup internal temperature change is 5C. On 20m, my K2 will show a warmup drift of about 5 Hz. This shows what you can achieve if you run a careful set of experiments with different resistor values. I only know of a few people who have actually adjusted the resistor values. It is a long time consuming process with very careful data measurement. However, you can reduce your drift rate following the printed procedure. -John KI6WX - Original Message - From: [EMAIL PROTECTED] To: Elecraft@mailman.qth.net Sent: Wednesday, March 15, 2006 1:58 PM Subject: [Elecraft] K2 frequency drift Two questions for the group: 1. My K2, serial 5120, has worked flawless since I built it last fall...except that about a week ago, friends on a 20m net I work daily said I was low about 40 Hz in frequency. (Frequency calibration checked occasionally against both my external counter and WWV had been right on.) I transmitted first maybe 2 minutes after turning the rig on. So I dialed up about 40 Hz (.04 kHz) to get on frequency. In the next 15 minutes, I had to move the indicated frequency down slowly to the exact net freq. Drift was the obviously the problem. Since then, I've turned the K2 on early and found that by net time, it was on the exact frequency on the LCD. However, just after turning it on (room temp constand at about 68F), tuning WWV on 10 MHz (equalizing the stations's audio tone on USB and LSB) shows I'm low by 40-50 Hz, drifting up to indicated freq. in 15-20 minutes. I know that resistors RA and RD on the thermister board control drift rate, and some months ago there were comments here on how to compensate, but I didn't retain the thread. Anybody care to provide that advice again or new comments? 2. I'm currently building a KPA100 internal amplifier kit, and I'm wondering if the added heat creates drift or frequency calibration problems. Dave Martin ___ 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 ___ 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
Re: [Elecraft] DDS-VFO Maybe off Topic
Lee; A DDS VFO does have some issues when used to directly drive a transmitter. The biggest one is spurious outputs. These may be only 70 dB down from the carrier and a few kHz to 100's of kHz away. Now when you are running low power, such as the KX1, this doesn't matter too much. But if you directly run a kW from a DDS VFO, you may make some other folks not too happy with your spurious outputs. -John KI6WX I've been researching the DDS VFO topic on the Internet and found that somethings have been done in this area in the USA, but most of the sites are found in Japan or Europe. Why has the DDS-VFO type of circuit caught on here? I am looking for a kit or a project I could build for some Xtal control rigs I have rather than buy Xtals. Seems to me that would a nice way to go. I know that Flex Radio has done quite a bit of work with DDS and so has Elecraft. I wonder if there is a market out there for DDS VFO technology and a crystal replacement Lee - K0WA ___ 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
Re: [Elecraft] Cooling fans
Kevin; For some of my K2 power tests, I've placed a single 12V fan on the heat sink with 6-32 screws through the fan mounting holes to hold the fan about an inch above the heat sink. The fan blows air down onto the top of the heat sink. With that combination, I can run key down full power for a half-hour without excessive heating on the output transistors. -John KI6WX Hello all. I'm getting my K2/100 ready for sweeps and have decided to add some aux cooling. I have a couple of 3 computer case fans and was wondering from those who've done the same about placement and whether blow the air onto the heatsink or suck it through. Thanks for your input. R. Kevin Stover AC0H K2/100 # 4684. ___ 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
Re: [Elecraft] K2 PLL Temp Compensation adjustment
Nigel; I designed the PLL stability mod for Elecraft. The mod was designed to compensate for the drift in the average PLL reference crystal. These crystals do vary some by lot, and the drift can be further reduced by adjusting the value of Ra as explained in the manual. The drift will also vary by band, and you might want to measure your drift on several bands. Don't assume that the drift will be worst on 10 meters. My K2 actually shows its worst drift on 30 meters, and its lowest drift on 10 meters. The main reason for this is that the PLL reference stability changes with its frequency. From the data you present, your drift is several Hertz per C. Tuning Ra can reduce the drift to less than 1 Hz/C on the worst band. My K2 shows a worst-case drift of 0.5 Hz/C measured from 10C to 50C. I tuned resistor Ra to minimize the drift on all bands. In your case, you do need to reduce the value of Ra. An initial measurement using Ra at 27K would be a good start. You may find it necessary to use 1% resistor values to get the lowest possible drift. -John KI6WX - Original Message - From: Nigel [EMAIL PROTECTED] I want to fine tune the temp compensation by adjusting the resistor RA, currently at 33k and would like to confirm my thinking before starting. My K2/100 drifts down about 50Hz after 30 minutes from turn on and stabilizes. After a good period of transmitting which gets the fan on high it will drift down another 40 to 50Hz. The PLL range is 13.26kHz The uncompensated oscillator drifts down with a temperature increase therefore I need to further increase the compensation. To achieve this I need to decrease the value of RA. Perhaps 27k or 22k? Have I got this right? 73, Nigel ZL2DF ___ 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
Re: [Elecraft] PLL Reference Oscillator out of spec
Mike; That is way out of spec. Make sure you all of the components installed in the correct location. Double check that you go the varactor diodes in the right location; this circuit uses two different types. Also check the DC voltage on the varactor diodes to make sure it varies from 0 to 8 volts. If everything checks out okay, ask Gary to send you a new crystal and check that one out. -John KI6WX - Original Message - From: Mike KL7R [EMAIL PROTECTED] I have completed Allignment and Test, Part II I need help with the PLL Reference Oscillator Range Test: Ref High Freq 12098.1 Ref Low Freq 12092.56 Range (kHz) 6.35 Which is out of spec. The Rev E and Rev F books say minimum of 9.8 khz I am using a single XTAL at X1/X2 (ECS V 12.09-S KOREA G0) I am using a shielded 10mh at L31) Rev B boards. Rev E manual The rig works on receive on 40 meters FB I dont have the K2 Temperature-Compensated PLL Reference Upgrade. How much does that Upgrade cost? Mike KL7R Was Ser #1938 (unbuilt - then upgraded to rev b boards) Now Ser #3373 ___ 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
Re: [Elecraft] Testing the compressor on K2 #4913
Ken; The compressor uses a power detector to measure the power level and it then uses that to set the audio gain. This results in no distortion of the audio signal. It is possible to run digital modes such as PSK31 through the compressor without adding any significant distortion to them. It is also possible to increase the compression level up to 16:1 by changing a resistor value. I'm not sure I would recommend that because every background noise in your shack could be transmitted at full output power. -John KI6WX - Original Message - From: Ken Bessler [EMAIL PROTECTED] Is the design of the K2's compressor so that even at 4:1, it's not too harsh? I've been using 2:1 for normal ops and 4:1 for difficult contacts. My mic is an old CB Cobra hand mic (600 ohm). I also have a headset mic salvaged from a cell phone (2.2k). I don't use that one much. I talked to KB0OMQ (2 miles away) on 40m today and had him rate the compressor for quality at 1:1 and 4:1. He said there was no difference in quality - just in strength. That was on the CB mic. That had me scratching my head. Surely, 4:1 compression would sound terrible so close in? I'm used to my FT-857D where at 65 of 100 it sounded good but at 100 it was only good for busting pileups. I would get complaints of my audio if I forgot to turn it down for a ragchew. I'm pretty sure my compressor is working - I get much more power for a given sound with it set to 4:1. Is the K2's compressor just THAT clean? ___ 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
Re: [Elecraft] Tuner efficiency question
Parker Don; I haven't tried to measure the efficiency of the Elecraft tuners. It is a fairly difficult measurement to make correctly when the input and output impedance are significantly different. However, there are two effects to consider in tuner efficiency. At high power, an inefficient tuner can generate significant amounts of heat, which can destroy components. A 1kW transmitter into a 70% efficient tuner will generate 300 watts of heat in the tuner. The second effect is the loss of signal at the receive station. A 90% efficient tuner will lose 0.5 dB; a 70% efficient tuner will lose 1.5 dB. The 1 dB difference will not have any noticeable effect on the ability to receive CW. Even on digital modes, it will only have a minor effect on the received error rate. Other factors, such as QSB, QRM, or QRN, will have a bigger effect. As long as the Elecraft tuners are reasonably efficient, they shouldn't have any significant effect on your ability to communicate. -John KI6WX Parker et al, QST did a review and test of a bunch of balanced tuners a year or so back. I don't remember too much of it now but remember being shocked at how high the losses typically were. As I recall efficiency ran in the 65 to 75 percent range for many of them. The Johnson matchbox was the most efficient by far (90% or more??) but did not cover all bands. I have not really studied this issue but have always been interested. My gut feel is that often much of the loss in these tuners (when driving a balanced line) is in the internal balun which is at the output of typical tuners and is driving a balanced line to the antenna which often has a horrendous SWR. The high SWR on the balanced line is not itself a problem because balanced twin line or ladder line feeders can easily handle the high currents and voltages with low losses but the poor balun can quickly get too hot to touch because of the high circulating currents within the balun. Don K7FJ K2 4438 I've been using my QRP K2 for the last 2-3 years with a full sized Palstar tuner. I use a variety of antennas from 160 to 10 meters, fed with coax, ladder line, choke baluns, the Elecraft balun, etc. I'm thinking about going to an auto tuner (Dayton Hamvention coming). Has anyone compared the efficiencies of the very small tuner like the T1, the KAT2, and larger tuners like the Palstar? (I've been the Johnson KW Matchbox route as well.) Intuition tells me there is something lost when going to very small components packed into a tiny space compared to large air variables, big roller inductors, etc., but I don't have anything to back up that gut feel. Anyone make any measurements? Parker K2 2636 WD8JOL ___ 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
Re: [Elecraft] PLL range (L31)
Mike; The recommended minimum PLL reference range of 9.8 kHz provides plenty of margin for operation on 160 meters. There is no need to increase it beyond that range. -John KI6WX - Original Message - From: Mike Markowski [EMAIL PROTECTED] My K2 passed the PLL range test with 9.84 kHz, so it juuust surpasses the 9.8 kHz lower limit and seems fine after some initial testing on 160m. But while I have the radio pulled apart building the 100 W stage, would it be worthwhile replacing L31 to get more comfortably in the middle of the PLL range? Or if it ain't broke, don't fix it? Thanks very much, Mike AB3AP ___ 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
Re: [Elecraft] Low PLL reference oscillator range
Paul; I designed the temperature stability part of the PLL reference oscillator. The PLL reference tuning range needs to be a minimum of 9.8 kHz if you want to operate on 160 meters. A tuning range of 8.8 kHz will not work at 1.8 MHz. If you only want to operate down to 3.5 MHz, a PLL reference tuning range of 8.8 kHz is fine. The 8.8 kHz that appeared on the Elecraft web site was a typo - it has now been corrected to 9.8 kHz minimum. ECS has not been able to control the Q of the 12 MHz crystals as tightly as we would like. When they deliver higher Q crystals, the tuning range becomes narrower and the larger 12uH inductor is required to compensate for the higher Q crystals. -John KI6WX - Original Message - From: Paul Bruneau [EMAIL PROTECTED] 9.8 may be fine, but I have 9.26 (see below) :) I will check out the What's New section as Dave G3VGR suggested, and if that doesn't make sense to me I'll contact Elecraft as Dave Lowenstein suggested. Thanks all, and any additional comments definitely welcome! -Paul On Apr 21, 2005, at 7:08 PM, Tim Cailloux wrote: 9.8 is fine. Wayne has mentioned in the past that 8.8 is the real minimum. I just finished #4539 and I was at 9.8 also. .. Original Message ... On Thu, 21 Apr 2005 18:55:06 -0400 Paul Bruneau [EMAIL PROTECTED] wrote: My High freq: 12099.03 My Low Freq: 12089.77 My range: 9.26 ___ 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
Re: [Elecraft] Potential Elecraft Kit
One of the problems with designing and selling kits is the production volume. Will enough of the kits be sold to justify the cost of developing the product. I don't know if there is enough demand in amateur radio to justify the development cost of a spectrum analyzer. Let me state the design specifications of a hypothetical high-performance HF-VHF spectrum analyzer that could be developed as a kit that would retail for $500. To keep the cost down, the analyzer would use a PC for control and display; the control of the RF portion would be done through a USB interface. The parts to do this design are available today - no great invention is required. Specifications Frequency coverage: 100 kHz to 160 MHz Resolution bandwidth: 100 kHz to 1 Hz Video bandwidth: 10 kHz to 1 Hz Dynamic range: 80 dB Power measurement error: 1 dB Maximum sweep speed: 10 MHz/second Maximum input power: +20 dBm Input noise figure: 20 dB Windows software included for control, display, printing and saving data; user supplies the PC. Option for $150 Tracking generator to make instrument into scalar network analyzer It would take about a person-year of effort to design the hardware, write the software, and create manuals. However, I think you would only sell about a hundred units per year. That makes the development cost too high to justify the effort. -John KI6WX Gang, One of the insturments I always wanted for home use was a spectrum analyzer. Nice to have sound card analyzers with software and all, but a real rf analyzer in a small, functional package would be so great. With some careful trade off decisions it might even be affordable! The display is a big headache if you don't have a good Oscope handy but a creative designer [or two] might be able to do the job. I suppose it would not have the broad appeal of a K1, 2 or even a very compact antenna tuner, but it might appeal to a few hundred hams and others who do bench work. Wayne K9NE Yes, I know about the projects already on the web, but how many of you have actually rounded up all the stuff to build that one? ___ 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
Re: [Elecraft] PLL Range (was K2 #4785)
Mark; I would recommend using the 12uH inductor. I designed the K2 PLL temperature stability mod and it is my recommendation that you not have an oscillator reference range below 9.8kHz for the most effective performance of that circuit. -John KI6WX - Original Message - From: [EMAIL PROTECTED] I'm just at the point of testing the PLL Reference Oscillator Range as well and am measuring 9.11 kHz. This is low compared to the spec of 9.8 to 15 kHz per the manual. Before I proceed to much farther, is 9.11 kHz okay as is? Should I be getting a 12 uH replacement L31 as well? What is the downside of leaving it as is? Mark, NK8Q K2 S/N 4786 ___ 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
[Elecraft] Question on Moving to Montana
I'm considering moving to the Bitterroot Valley south of Missoula, Montana. Is there anyone on this list who lives in that area who could provide me more information on living there? Please reply directly to me since this email is grossly off topic. -John KI6WX ___ 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
Re: [Elecraft] K2 PLL Oscillator Range Test failure (barely)
Scott; You definitely want the PLL reference to tune at least 9.8 kHz so you don't compromise the performance on 160 meters. If L31 is 10uH, going to 12uH will cure the problem without causing any bad side effects. You can ask Elecraft to send you the different value inductor. The narrow and wide tuning ranges that sometimes occur on the PLL reference are due to variations in the Q of the 12 MHz crystal. This is not always easy to control. Elecraft has implemented a tighter spec with the crystal vendor so this problem is less than it was in the past. -John KI6WX On page 60 of the K2 manual the PLL Reference Oscillator Range Test asks for the Ref. High Freq. and Ref. Low Freq. measurements. I have HI = 12099.67 LO = 12090.50 DIFF 9.17 which is less than the 9.8 to 15 kHz required by the manual. Everything else looks good. Any ideas? Any help would be appreciated. Thanks. ___ 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
Re: [Elecraft] K2: VFO Drift and Temperature-Compensated PLL ReferenceUpgrade
Michael; Let me make a few comments about this circuit. I'm trying to understand a bit more about temperature-related VFO drift in the K2. My K2 sits in the basement where it is currently seeing stable ambient temperatures around 67F. When using 10 MHz WWV as a reference, I see approximately 40 Hz of drift (10,000.03 to 9,999.99) over a 30 to 45 minute period from a cold start. I am not transmitting during this period, I assume this is just due to a slight heating (can't be much of a temperature change) of various resistors, capacitors, inductors, and varactors. This is clearly in-specification as it is much less than the 100 Hz that is specified in the manual. ;^) A K2 or K2/100 will warm up about 5-10F above the local ambient temperature due to the internal power dissipation; more options installed will push this toward the higher number. My K2 is serial number 4137, so it has had the Temperature-Compensated PLL Reference Upgrade from the start. The Temperature-Compensated PLL Reference Upgrade documentation says that you can check the VFO drift by transmitting for a while to raise the temperature of the radio 15 or 30 degrees F _AFTER_ you have allowed a warm-up period of 30 or more minutes. This appears to infer that there is a difference in the nature between warm-up drift and post warm-up drift. If so, can someone explain what that difference is? There is no difference in the root cause of the drift. This adjustment procedure was designed so that you could make a consistent measurement of drift as you adjusted the value of RA. It is possible to reduce the 20 meter drift to less than 50 Hz with a 50F temperature swing. My K2 has been tested with this mod over a temperature range of 40F to 130F. The drift is not as well compensated below 50F, so you will see somewhat more drift if you operate outside in the winter. I haven't performed the formal post warm-up drift testing, but I plan to give it a try to see how stable the VFO is after warm-up. This raises another question... Will making any changes to resistor RA on the PLL thermistor board have any affect on the 40 Hz of warm-up drift (as opposed to the post warm-up drift), or is this something that can't really be addressed by the Temperature-Compensated PLL Reference circuit? Reducing the drift following the test procedure will also reduce the warmup drift. The warmup drift on my K2 is less than 20 Hertz as determined with the front panel frequency display and WWV. Thanks, Michael N9BDF PS It was nice to see that resistor RA was placed at the top of the PLL thermistor board -- makes it much easier to fine tune the temperature compensation! :^) This was intentionally done in the design so that any K2 user could improve the performance with a little additional work. That is also why RA is a 1/4 watt resistor and all of the other ones on the circuit board are 1/8 watt resistors. -John KI6WX ___ 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
[Elecraft] KX1 Wind River Mountains
Last summer, I had several folks track my location as I solo hiked through the Wind River Mountains on an historical exploration trip. I used a KX1 to send out my evening GPS location. The historical results of that exploration are now posted on the web at: http://home.pacbell.net/johngreb/fremont1842.htm This trip was able to determine with a high degree of certainty which mountain John C. Fremont climbed in August 1842. This is a question that has been in controversy for many years. -John KI6WX ___ 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
Re: [Elecraft] K2 Phase Noise
Bob; I have a mod that will reduce the K2 phase noise. The implementation of the mod is not easy. Some of the changes require the ability to measure phase noise, and most folks don't have this capability. The mod can also degrade the PLL stability. Therefore, I do not plan on publishing the mod. My work on K2 phase noise has convinced me that the design is pretty close to the best performance that you can get on this type of oscillator design. -John KI6WX - Original Message - From: R March [EMAIL PROTECTED] Has anyone come up with a mod that reduces phase noise on the K2? Thanks, Bob ___ 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
Re: [Elecraft] KPA100 C83
Brian; When we built the original KPA100 prototypes, the optimum value of this capacitor was not known. If you make it larger, the amp draws more current on 10 meters but is more stable. With smaller values, you get better efficiency on 10 meters but it is more prone to spurious oscillations. It is a lot easier to remove the capacitor when it is soldered directly to the pads, so the instructions were changed to solder it to the pads. The original prototypes and earlier production KPA100's used 1200pF. Experiments showed that the value could be reduced without problems. My KPA100 has run for a long time with the value at 820pF. It was eventually decided that 1000pF was reasonable, so the production kits were changed to this value and updates sent out to the earlier KPA100 builders. Today, the part could be mounted in the holes without any problems. -John KI6WX - Original Message - From: Brian Wruble [EMAIL PROTECTED] Hi guys: While assembling my KPA100, I unfortunately charged right by the warning not to install C83 through the holes in the board. I removed the 1000ufd cap and reinstalled it as recommended. However, I am very curious as to why it is specified to be mounted this way. I have reviewed prior postings here, and found this question, but never saw any answers. Tnx de Brian W3BW ___ 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
Re: [Elecraft] Audio levels in K2
There is an alternative way to increase the K2 audio output to headphones. The K2 RF board contains series 82 ohm resistors at R35 and R36 to reduce the volume for more sensitive headphones. If you have low impedance or insensitive headphones, the value of these two resistors can be reduced to give you more audio output. There is an easy way to check if this will help. Plug your headphones into the K2 external speaker jack on the rear panel. If you now have plenty of volume from the headphones, reducing the values of R35 and R36 will fix the problem. -John KI6WX - Original Message - From: john [EMAIL PROTECTED] Hello All, I was chasing DX on the low end of 10m yesterday (good paths to VK!) and noted that even with phones on, I had the AF gain all the way up...and could use more. Perhaps this was due to the headphones I was using, but I wonder if others have noted the same thing. I think this is the only rig I've got that does not have enough AF gain to blast me out of the phones. On vy strong sigs, I don't need the gain, but on the very weak ones, I could use more. Thanks for your insight John K5MO ___ 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
Re: [Elecraft] Re: KX1 PSK31? [how about FSK?]
Chas; You don't need to add a reactance modulator to the KX1. The AD9834 DDS will directly generate FSK. It would almost be a trivial mod for Elecraft to add a firmware option for FSK31 that is activated through the key jack. A computer is a lot heavier to lug around than a KX1. A small lightweight portable keyboard and display would be much more compatible. The marketing issue would be cost. It would probably cost a substantial fraction of the KX1 price to sell such an option. -John - Original Message - From: Charles Greene [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Friday, October 08, 2004 3:58 AM Subject: Re: [Elecraft] Re: KX1 PSK31? [how about FSK?] John, I would think the first step should be to add a reactance modulator and simple interface to a computer sound card, ala the psk20, to the KX1 and use it with an ordinary computer, running a program like MixW. Mixw supports FSK31 by sending an FM modulated signal via the computer sound card to the mike input of a transceiver. For example, I can operate FSK31 on my K2 now; I just have to select it in MixW. I have a simple interface made up. Anyone can do this with any rig that operates on PSK31. The only difference is that the KX1 finals would operate class C, and the other rigs finals would operate class AB or some other linear mode. Of course that means you carry a LapTop with you when you go portable, but some have stated that isn't a problem. To have Elecraft to make a small keyboard and display that would plug into a KX1 type radio and allow if to transmit and receive FSK31, seems to be reinventing the computer. HP, Dell, etc do it pretty well, Yes I'd like to have one, but from Elecraft's point of view I'm not sure there is much of a market for that. Also, I'm not sure who you would talk to, as I have never seen FSK31 used, but maybe we could start an Elecraft net. 73, Chas, W1CG ___ 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
Re: [Elecraft] Re: KX1 PSK31? [how about FSK?]
The original PSK31 implementation included an option for FSK31. Theoretically, PSK31 should provide a 2-3 dB improvement in signal to noise ratio over FSK31. In practice, it is necessary to back off the power amplifier by a few dB to keep from generating an excessively wide signal, whereas FSK31 can be run in a class C amp at full power (as long as your amplifier can handle transmitting a continuous carrier). This difference can negate the improved SNR of PSK31. Since may of the digital mode software products support FSK31, it would be an interesting experiment to test its efficiency in a real communication system. A KX1 could trivially generate a FSK31 signal. Decoding it might require a more powerful processor, but is doable. The interesting question is how you interface the input and output to the operator. A display and keyboard would require a larger package or a separate module that plugged into a KX1. There are some small keyboards and displays that would work for this type of application. So perhaps we ought to ask Elecraft to make a small keyboard and display that would plug into a KX1 type radio and allow if to transmit and receive FSK31. It would even be a nicer option if you could plug it into a K2 and transceive both FSK31 and PSK31. -John KI6WX - Original Message - From: wayne burdick [EMAIL PROTECTED] However, it may be possible to operate the KX1 in any low-data-rate, dual-tone FSK mode. This is compatible with a class-C final amp, and should require only a firmware change. The KX1's key jack would serve as the data input/output port for connection to a computer. Unfortunately FSK (e.g. traditional RTTY) is not quite as popular as PSK31 for QRP use, even though good reliability is possible with some variants. ___ 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
Re: [Elecraft] K2: KAF2 Versus 2.2 kHz KSB2
The KAF2 actually starts rolling off about 1 kHz. This is nice for reducing the background hiss, but you do need to remove the KAF2 if you want to use Spectrogram to measure crystal filter frequency response. -John KI6WX - Original Message - From: Linden, Mike (BRC-Hes) [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Thursday, August 26, 2004 10:43 AM Subject: [Elecraft] K2: KAF2 Versus 2.2 kHz KSB2 I plan on building my KSB2 to KI6WX's 2.2 kHz crystal filter bandwidth specifications (which is now the current Elecraft bandwidth). Should I shift the KAF2's low-pass filter roll-off higher in frequency when I build it to account for the increased bandwidth of the KSB2, or will the low-pass roll-off be adequate as is? Thanks, Michael N9BDF K2 #4137 PS The Amateur Radio Emergency Communications Consistency Act (HR 1478) and the Amateur Radio Spectrum Protection Act (HR 713 S. 537) are in Congress. Please contact your Congressmen to ask for their support of these bills! See the following ARRL link for details: http://www.arrl.org/govrelations/ http://www.arrl.org/govrelations/ ___ 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 ___ 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
Re: [Elecraft] 2.3kHz KSB2 feedback
The new standard version of the KSB2 filter is the same as my 2.2 kHz design. Elecraft measures the bandwidth to the 6 dB points, so they quote the bandwidth as 2.3 kHz. If you want to use my 2.5 kHz bandwidth design, you now only have to change 4 capacitor values. -John KI6WX - Original Message - From: Don Wilhelm [EMAIL PROTECTED] Folks, I didn't know that the 2.2 (or 2.3) kHz SSB filter had become the 'standard', but it does get my vote. I have long advocated the KI6WX 2.2 kHz filter bandwidth as my choice for a great compromise between 'punch' for QRP operation and good SSB fidelity. It does offer a flatter passband than the original 2.0 kHz SSB filter. To my mind, the 2.5 kHz bandwidth is a bit too wide, but many folks favor it for the increase in fidelity. I do recall there was a time when the Collins 1.8 kHz mechanical filter was considered the ultimate for communications effectiveness - at least in the receive part of things - my how times and values have changed!!! 73, Don W3FPR - Original Message - I recently built a KSB2 with the now standard 2.3Khz filter configuration. I have been recieving compliments on the TX audio quality. Some have said the SSB audio is the best they have heard from a K2. The filter sweeps on Sectrogram show less ripple and more symmetry then my previous 2.5kHz KSB2. John K5XTX ___ 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
Re: [Elecraft] KI6WX...Backpacking w/KX1
I just made it back last night from wandering around Wyoming and Montana after finishing the trip in the Wind River Range. I'll try to post a trip report later today. -John KI6WX - Original Message - From: [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Friday, July 30, 2004 10:19 AM Subject: [Elecraft] KI6WX...Backpacking w/KX1 Anybody got a status report on KI6WX backpacking in Wyoming mountatins with his KX1. 73 de K5AVJ Lynn Bailey ___ 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 ___ 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
[Elecraft] Climbing Trip with KX1
I took a KX1 with me on a solo climbing trip into the Wind River Mountains in central Wyoming in late July. The KX1 was used to send a GPS position each night so my location could be tracked if anything went wrong. N6KR and N0SS contacted me each evening at 0200Z to get the position. The weather was bad with two thunderstorms per day. This left a lot of standing water around which was very popular with the mosquitoes. The mosquitoes were the worst I have ever seen, including an Alaskan trip. The only way to avoid them was to keep moving or to hide in the tent. I met most of the trip objectives except for a climb to the summit of Fremont Peak. The weather wasn't going to permit the climb, so after three days of mosquito attacks, I bailed out early. For those interested, a brief summary of the reason for the trip is at then end of this message. I carried the KX1 with a set of lithium batteries, the portable paddle, and a 30m dipole made from 50' of #24 speaker wire. The speaker wire was split at one end to form the dipole and the rest of it was used for feedline. Total weight was a little over a pound including a plastic carrying case. The antenna was strung up about 6 feet off the ground using any convenient nearby trees. The antenna loaded up well on both 20 and 30 meters using the KX1 antenna tuner. We primarily used 10108 kHz, but had backup frequencies on 20 and 40 meters. The KX1 frequency accuracy was quite useful. On Monday evening, I got the antenna up and was on frequency about 10 minutes early. I hit the antenna tune button, and N0SS came right back on the frequency. I sent the info and Tom passed it on to Wayne when he arrived at the correct time. On Tuesday, I knew we were in trouble from solar activity. I could only hear WWVH on 10 MHz, no WWV, and both 30 and 20 were dead. No luck on either band. On 40 meters, I could hear both N6KR and N0SS calling (both were weak and not 100% copy), but they were unable to copy me. A more efficient antenna on 40 meters would have helped. By Wednesday evening, I was on my way out so no attempt at a contact. The mosquitoes were so bad that I was averaging about 5 kills per minute while hiking out. Even moving wasn't much help. The total trip covered about 30 miles. I was carrying 55 pounds including the KX1 and another half pound of a 2 meter FM rig that would have been line of sight to the Pinedale repeater once I was on the upper slopes of Fremont Peak. My border collie as carrying another 10 pounds. We could have gotten by with less weight, but we had everything we needed to survive the storms that were pounding us each day. The storms each day put on quite a show. We would have lightening strokes followed by earth shaking thunder, several times with less than a second separating them. The thunder would echo around the mountain valleys and sometimes would still be audible 50 seconds after the initial stroke. Most of the storms would also drop hail along with heavy rain. The water collected everywhere and mud was a problem. The purpose of the trip was to gather some on the ground data on John C. Fremont's military mapping trip into the Wind River Range in 1842. On August 15, 1842, he had climbed a mountain that he believed to be the highest point in the Rocky Mountains. There has been a historical controversy about which peak he climbed. Fremont took a number of scientific measurements on his trip. I have re-analyzed these measurements and believe they point to the answer to this question. I was able to locate the two points at which the drawings published in Fremont's 1843 Senate report were done. I was also able to locate Fremont's 1842 campsite at Island Lake based on his written description of the site (its unlikely that there will be any archeological remains since the site was only occupied for 3 nights). I got a good WAAS corrected GPS position on the location and elevation of the campsite. -John KI6WX ___ 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
Re: [Elecraft] Climbing Trip with KX1
Lynn; For the worst storms I had a fairly protected campsite. A much higher rise behind the camp would have taken most of the hits. The best thing for mountain lightning protection is to make sure you are not a high point. Valleys are good places for campsites. If you have to lean your neck back to look up at a nearby summit, you are reasonably safe from a strike. Also, don't leave the antenna feedline in the tent during a storm; the electromagnetic field from a nearby strike can induce significant amounts of current flow which could be hazardous. -John - Original Message - From: [EMAIL PROTECTED] John...thanks for giving us a backpack trip report. Sounds like the lightning was life-threatening. What's the key to surviving a lightning storm in the mountains? We got caught in one at about 10,500' when we were hiking near Silverton, CO..we also got hailed on. You must've been within a few hundred feet of the lightning strikes. Would you do anything different with the ham gear? Maybe take a 40 mtr. dipole, too? Also wonder what the CW abbreviation is for mosquito? QRN/SUX? Or maybe you could make one up.QMQ 73 de K5AVJ Lynn (K2 #1411) ___ ___ 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
Re: [Elecraft] Icom IC-7800 review
Bob, indeed the IC-7800's close-in phase noise is so bad that measurements of IMD and BDR are noise limited. As is detailed in the August QST article about Product Testing, ARRL chooses to measure the composite result including phase noise issues (see 3rd paragraph under both BDR and IMD sections on page 34 of August 2004 QST). G3SJX simply lists noise limited but ARRL's Expanded Test Reports shows the composite result. Indeed the K2 beats the IC-7800 for BDR but is equal for IMD at 1 kHz spacings. As has been discussed here previously, the K2's close-in performance also degrades quite a bit for signal spacings under 5 kHz. I'm not sure whether this is due to filter blow-by or phase noise. Here are the comparative measurements from ARRL's ETR's for the K2, IC-7800 and Orion at 5 and 1 kHz spacings respectively: Rig IMD BDR (at 5/1 kHz spacings) K2 91/67 134/116 IC-7800 89/67 115/96 Orion 92/84 130/118 Bill; I have extensive measurements of the K2 phase noise on all bands. On 20 meters at a 20 kHz spacing, both the oscillator phase noise and the mixer IP3 contribute to the overall dynamic range. At less than 10 kHz, the phase noise is dominate and limits the DR3. I know that filter blow-by is not an issue at 5 kHz with the CW filter. Greater than 20 kHz, the K2 DR3 is primarily limited by the mixer IP3 and the DR3 gets up to about 100 dB. -John KI6WX ___ 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
