Re: [Elecraft] K1 Future Improvements to VFO D3, R17, R18 any one tried??
There is one very simple solution to greatly improve the stability of any VFO: blowing air over the equipment case. It's not obvious, but by keeping the case cool, you keep air inside the case close to ambient temperature. The stability gain can be incredible--around an order of magnitude. I like to think it also reduces the chance of component failure due to to heat. You can place the fan on a stand behind or next to the transceiver to blow over the top. I place the fan right on the top, horizontally, raised with spacers in each of the fan's mounting holes. (No holes in the case--just gravity holding the fan.) I drop the voltage to the fan to about 50% to 75% to keep it quiet. I've not tried this with a K1, but it sure works with other transceivers. 73 Dick, K0KK On Dec 19, 2005, at 4:31 PM, Mike Morrow wrote: But returning back to the original question, I'd say that if anyone finds something simple that improves the already excellent stability of the K1 VFO, I'd certainly be interested in hearing about it. Happy experimenting! 73, Mike / KK5F ___ 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] K1 Future Improvements to VFO D3, R17,R18 any one tried??
Don wrote: I would not regard 100 Hz of drift in the K1 as a design problem at all - The K1 spec is for drift less that 200 Hz after a 5 minute warmup. The fact that the K1 does not use a DDS vfo is not a 'design problem' as was stated... I wholeheartedly agree. I had been using (and still use) three of SWL's wonderful DSW-series mono-band DDS rigs before I got my K1 in late 2000. I was fully prepared to be disappointed by the stability of the LC VFO design of the K1. Instead, I quickly found that I was very pleased with the stability of the K1's VFO. but surely was a design decision based on price/performance with components available at the time it was designed. At the time the K1 was designed, DDS units were not as available as today and were still quite pricy - by the time the KX1 was designed, the cost of DDS had dropped significantly. I would express a different view. I would hate to see the performance of the K1 *degraded* by the use of a DDS VFO. After experiencing how well the K1's LC VFO performs, I would now NOT buy a K1 if it used a DDS frequency generation scheme such as that found in the KX1 or DSW. A simple DDS VFO design such as is found in KX1 or DSW units puts a fair amount of spurious output directly into the higher level transmitter stages, and into the receiver mixer. This junk degrades transmitter spurious output quality and receiver performance. The K1's LC VFO and hetrodyne crystal oscillator output is far cleaner than any current DDS-only VFO. Those who wish for every little enhancement possible in the RF performance of a radio will NOT choose a simple DDS VFO design. More sophisticated rigs that use DDS use it in conjunction with a PLL to generate a much cleaner signal rather than using the direct raw output of a DDS chip. Perhaps soon a combo DDS-PLL chip that is low-cost and low-power will arrive for use in our QRP rigs and reduce the concern about spurious output. An additional issue arises from the requirement in the KX1 for the DDS to produce output frequencies over a very wide range as it changes band-to-band, mode-to-mode, and receive-to-transmit. The KX1 DDS generates all of the required frequencies directly, rather than through hetrodyning with crystal oscillators. The clocking rate for current low-cost low-power DDS chips like the KX1's AD9834 is limited to 50 MHz, and the maximum output frequency at that clock is about one-third of that (16.6 MHz). This means that coverage of any ham band above 20m is fundamentally out of the question. However, a simple DDS VFO has a few advantages over the LC VFO: Excellent stability, resetability, wide frequency span, and adaptibility to digital control. Only the first two are usually apparent to the operator. OTOH, the step-wise incremental tuning and the manipulations required to change the tuning step make DDS VFO tuning far less natural than that of the continuous output of an LC VFO that tunes where and just as fast or slow as I turn the dial. So the options are clear. Choose the simple DDS rig if crystal-like temperature stability and resetability are most important to you. Choose a LC VFO rig if overall RF performance and naturalness of tuning are most important to you. I fail to understand how anyone could refer to this a 'design problem'. Agreed. The *superior* performance of the LC VFO over the simple DDS VFO make it the choice of those for whom the RF signal performance of their radio is important. It's a very *positive* design feature of the K1 over the KX1 that may go unrecognized by those unfamiliar with the technical issues at hand. But returning back to the original question, I'd say that if anyone finds something simple that improves the already excellent stability of the K1 VFO, I'd certainly be interested in hearing about it. Happy experimenting! 73, Mike / KK5F ___ 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] K1 Future Improvements to VFO D3, R17, R18 any one tried??
Paul wrote: Just reading page 59 of the K1 manual and it talks about provisions for improvements to the VFO temperature compensation And the use of D3, R17 and R18. Anyone tried this out and done any before and after tests. I've heard no reports of such experiments in the five years that I've had a K1 (#175) and been on this list. Reed, K7FLY, in early 2001 reported some things he did to improve temperature stability not involving any actual circuit changes (except replacing an abnormally temperature sensitive VFO votage regulator), at: http://www.qsl.net/ve3mcf/elecraft_reflect/K1_Temperature_Freq_Drift_Mgmt.tx t My old K1 with 170 kHz VFO span (and no stability mods) is surprisingly temperature stable, and I've not been tempted in the least to improve what is already very very good. It was recently reported that at least one K1 owner found VFO stability to be better with the capacitor supplied for the 170 kHz span than with the capacitor for the 80 kHz span. I've never used the 80 kHz option, so I can't report on a similar comparison. 73, Mike / KK5F ___ 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] K1 Future Improvements to VFO D3, R17, R18 any one tried??
I have mine set up for 80 khz and have absolutely no problems with temperature stability. In July for the FOBB, the top of my K1 got so hot I literally could not comfortably touch it. I was engrossed in the contest and didn't notice the sunlight through the trees focusing on the rig. In all that time, both heating up to sub-nuclear temperatures and cooling down to a comfortable 105 degrees in the shade, the K1 sat where ever I parked her. If anyone has temperature stability problems, I'd look for a defect, not a design change. Eric KE6US www.ke6us.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mike Morrow Sent: Sunday, December 18, 2005 9:13 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K1 Future Improvements to VFO D3, R17,R18 any one tried?? Paul wrote: Just reading page 59 of the K1 manual and it talks about provisions for improvements to the VFO temperature compensation And the use of D3, R17 and R18. Anyone tried this out and done any before and after tests. I've heard no reports of such experiments in the five years that I've had a K1 (#175) and been on this list. Reed, K7FLY, in early 2001 reported some things he did to improve temperature stability not involving any actual circuit changes (except replacing an abnormally temperature sensitive VFO votage regulator), at: http://www.qsl.net/ve3mcf/elecraft_reflect/K1_Temperature_Freq_Drift_Mgmt.tx t My old K1 with 170 kHz VFO span (and no stability mods) is surprisingly temperature stable, and I've not been tempted in the least to improve what is already very very good. It was recently reported that at least one K1 owner found VFO stability to be better with the capacitor supplied for the 170 kHz span than with the capacitor for the 80 kHz span. I've never used the 80 kHz option, so I can't report on a similar comparison. 73, Mike / KK5F ___ 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] K1 Future Improvements to VFO D3, R17, R18 any one tried??
Hi Don’t get me wrong, the K1 is operating well within specs, its just not so stable as the K2 or the KX1 I have in the shack. If anyone thinks theirs is stable try this, feed the output of the K1 into a program that will allow a waterfall display to be configured that allows about 1 hours worth of trace on screen , I use a QRSS morse prog that seems to work well for this, use a signal generator (I use the XG1 by Elecraft as a source). Turn on the k1 from cold and quickly tune in the signal at 7.040 for about 700Hz trace on the pc. Now every 5 mins record the traces freq on the pc or just let the k1 run for a hour and look at the trace. After do the same test with the K2 or the KX1 . I would be Very supprised if you still say the K1 has no drift, one interesting thing is that the drift aways seem down in freq after the first few mins, from cold the first 2-3mins produce a up drift of 10-40 hz before drifting down, I find about 100Hz drift after the first 5 mins in one hour. Also while doing the above test put a load on the k1 and put the key down for 10 sec or so and see what happens when you go back to receive. In practice I don’t find it any problem at all after the first 5mins but since elecraft have taken the time to print details about possible drift mod im sure even they will accept that its not a defect in an individuals radio but a design problem using a none DDS vfo. If you do a lot of tuning around like many do in a contest and your QSO's are contest type (i.e. very short) you will never notice this drift im sure! The display on the K1 still indicates the correct freq at all times. Regards Paul M0BMN -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of EricJ Sent: 18 December 2005 17:24 To: 'Mike Morrow'; elecraft@mailman.qth.net Subject: RE: [Elecraft] K1 Future Improvements to VFO D3, R17,R18 any one tried?? I have mine set up for 80 khz and have absolutely no problems with temperature stability. In July for the FOBB, the top of my K1 got so hot I literally could not comfortably touch it. I was engrossed in the contest and didn't notice the sunlight through the trees focusing on the rig. In all that time, both heating up to sub-nuclear temperatures and cooling down to a comfortable 105 degrees in the shade, the K1 sat where ever I parked her. If anyone has temperature stability problems, I'd look for a defect, not a design change. Eric KE6US www.ke6us.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mike Morrow Sent: Sunday, December 18, 2005 9:13 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K1 Future Improvements to VFO D3, R17,R18 any one tried?? Paul wrote: Just reading page 59 of the K1 manual and it talks about provisions for improvements to the VFO temperature compensation And the use of D3, R17 and R18. Anyone tried this out and done any before and after tests. I've heard no reports of such experiments in the five years that I've had a K1 (#175) and been on this list. Reed, K7FLY, in early 2001 reported some things he did to improve temperature stability not involving any actual circuit changes (except replacing an abnormally temperature sensitive VFO votage regulator), at: http://www.qsl.net/ve3mcf/elecraft_reflect/K1_Temperature_Freq_Drift_Mgmt.tx t My old K1 with 170 kHz VFO span (and no stability mods) is surprisingly temperature stable, and I've not been tempted in the least to improve what is already very very good. It was recently reported that at least one K1 owner found VFO stability to be better with the capacitor supplied for the 170 kHz span than with the capacitor for the 80 kHz span. I've never used the 80 kHz option, so I can't report on a similar comparison. 73, Mike / KK5F ___ 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.1/206 - Release Date: 16/12/2005 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.1/206 - Release Date: 16/12/2005 ___ How much free photo storage do you get? Store your holiday snaps for FREE with Yahoo! Photos http://uk.photos.yahoo.com
RE: [Elecraft] K1 Future Improvements to VFO D3, R17, R18 any one tried??
Paul, I would not regard 100 Hz of drift in the K1 as a design problem at all - The K1 spec is for drift less that 200 Hz after a 5 minute warmup. The fact that the K1 does not use a DDS vfo is not a 'design problem' as was stated, but surely was a design decision based on price/performance with components available at the time it was designed. At the time the K1 was designed, DDS units were not as available as today and were still quite pricy - by the time the KX1 was designed, the cost of DDS had dropped significantly. I fail to understand how anyone could refer to this a 'design problem'. 73, Don W3FPR -Original Message- ...snip... I would be Very supprised if you still say the K1 has no drift, one interesting thing is that the drift aways seem down in freq after the first few mins, from cold the first 2-3mins produce a up drift of 10-40 hz before drifting down, I find about 100Hz drift after the first 5 mins in one possible drift modhour. Also while doing the above test put a load on the k1 and put the key down for 10 sec or so and see what happens when you go back to receive. In practice I don’t find it any problem at all after the first 5mins but since elecraft have taken the time to print details about im sure even they will accept that its not a defect in an individuals radio but a design problem using a none DDS vfo. If you do a lot of tuning around like many do in a contest and your QSO's are contest type (i.e. very short) you will never notice this drift im sure! The display on the K1 still indicates the correct freq at all times. Regards Paul M0BMN ___ 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
