As a good engineer I should have stated what I measure with, sorry. Normal 2-tone test, and a HP 8591E spectrum analyzer.
Normally I like to do it with speech, i e fully modulate the radio and look at the sample 5 kHz on each side. That is IMO better then a 2-tone test since it will tell you more. And by the way, I did NOT say 2 dB, read below. As an anecdote you can look at this: http://sk3w.se/sm2ekm/view_photo.php?set_albumName=SM2EKM-pictures&id=FT_1000D http://sk3w.se/sm2ekm/view_photo.php?set_albumName=SM2EKM-pictures&id=KWM_2 We can see that the Collins KWM-2 is ca 10 dB better on adjacent channel compared to Yaesu FT-1000D. The FT-1000D is one of the best modern things around when it´s up to TX IMD. Anything else I have measured is worse then the FT-1000D. Receivers has been getting better but not transmitters that is the bottom line. / Jim SM2EKM ----------------------------- [email protected] wrote: > I am sure PSU regulation affects all other 12V radios in exactly the same > way. The only reason Elecraft users will see it more is because they are more > discerning. > > How do you measure IMDs? 2dB is a worthwhile improvement. > > It would be interesting to try a better supply cable and also to see if the > 20A cutout has any effect. > > Mike > > Jan Erik Holm wrote: >> Yes I´m beginning to think that K3 is more sensitive to PS >> then other radios, right now it looks that way. >> Then this should be in the manual!!! >> What happens is if I have a bad signal on the bands I will >> together with Elecraft get a bad reputation. I will of course >> tell everyone what I´m running and do have it operating >> exactly according to the manual. >> >> If this PS deal is the case with the K3 I quite understand >> and it´s no problem to me what so ever but it should be >> in the operating manual. Every user of a K3 should not >> need to be a super engineer and have to figure out things >> like this them self. >> >> This morning I increased PS voltage to 14.6V (14.2) under load, >> I was at 13.9V (13.5 load) before, I could see a "slight" >> improvement in IMD (1-2 dB). I am using the supplied high >> performance cable from Elecraft and IMO it does not have >> enough Cu area. Next But if Elecraft supplies it and it´s >> not good enough, what can I say? >> >> / Jim SM2EKM >> ------------------ >> AD6XY wrote: >>> Everyone knows it is important for the K3/100 to receive a solid DC >>> supply. >>> >>> If the supply drops significantly when high current is drawn several >>> effects >>> may occur: >>> >>> 1 - The Transmitted signal becomes wider than it should be >>> 2 - The power control loop is upset leading to unstable output power >>> 3 - In severe cases the radio might shut down, or engage sulk mode. >>> >>> Of course this does not apply to us, we are all experienced constructors >>> and >>> never make mistakes when wiring up our shacks. Like many people I run my >>> K3 >>> from a 13.8V DC supply that also supplies other items, in my case XV >>> transverters, an LP100, an LDG ATU etc. This supply is very good (tnx >>> BNOS, >>> 1980s) and only varies by a few 10s of mV between no and full load. >>> Originally when installing my K3/10 I used the supplied DC cable via a >>> powerpole distribution board with an appropriate fuse. In fact this >>> particular board had two fuses, one 30A one at the input and one at the >>> output plus around 1 metre of thick cable to the supply. This worked >>> fine. >>> >>> Later I upgraded to the 100W KPA3, and of course changed the fuse in the >>> distribution board. The DC voltage drop according to the K3 at 20A was >>> over >>> a volt, much no doubt due to the fuses and extra connections through the >>> distribution board. A 1 volt drop is not a problem for the K3 but will >>> cause >>> more IMDs on SSB. >>> >>> I now connect the K3 directly to the PSU with as short a DC cable as is >>> practical. It would be even better to use voltage sensing so the supply >>> is >>> regulated at the K3 end of the cable. >>> >>> Mike _______________________________________________ Elecraft mailing list Post to: [email protected] 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
