Dear Don, Thanks for your support!! there is a deep and sharp null for all bands except 80 &160m, cannot get lower than 1.3 for 80 and 1.8 for 160, I did check the core and it is the large dark gray core. I also removed T4 and did check the solder connections. No difference in results. Maybe asking Elecraft for a new FT50-43 core? I also will ask my colleague amateurs for another dummyload, just to be 100% sure. The current one I'm using is from Annecke and the freq it is capable of handling is 2 Ghz. 73 Koert PA1KW
Don Wilhelm wrote: > Koert, > > The absolute minimum voltage found in the C1 null (as observed at TP4) > is not as important as the depth of the null. > > If you cannot achieve a deep and rather sharp null, there is something > wrong with either T4 and its associated components or with your dummy > load. The actual voltage at the null will depend on the power level > used. > > Assuming your dummy load is good (you can check it with an antenna > analyzer), you should see a 1.0:1 SWR on all bands. > > Since you indicate a higher SWR on the low frequency bands, that > suggests that T4 does not have adequate inductance for those bands. > Check that you have used the correct core for T4 - it should be one of > the gray (ferrite) cores and not one of the black (powdered iron) > cores. Be certain that T4 has well stripped leads and is properly > soldered. If you observe toroid solder connections that look a bit > like volcanos, that lead was not well stripped - a good solder > connection will look like a mountain with concave sides - if it has a > convex shape, too much solder was applied and that fact can mask a > poor solder connection - wick away the excess solder and resolder > properly. > > 73, > Don W3FPR > > Koert Wilmink wrote: >> Dear all, >> >> Please find my emails to Elecraft support below. Is there maybe >> somebody with additional tips? >> >> Thanks!! >> >> 73 Koert PA1KW >> >> >> >> ----------------------------------------------------- >> Hi Gary, >> >> Sorry for my late response, but I had not the opportunity to work on >> this earlier. I moved houses and that took longer than expected. >> >> I did check the HV bias and that is 135volts. The diodes are ok and the >> voltage on TP4 2mV on receive and 240mv on transmit (tune). >> I did connect a good dummyload close to the KPA100. >> I did the re-adjustment of the SWR bridge but this provided me not the >> required results. The best results with adjusting C1 on 5 Watts is: >> >> 160m 1.8-1 >> 80m 1.3-1 >> 40m 1.0-1 >> 30m 1.0-1 >> 20m 1.0-1 >> 18m 1.0-1 >> 15m 1.0-1 >> 12m 1.0-1 >> 10m 1.0-1 >> >> Please help...... >> >> Best regards and 73, >> >> Koert Wilmink >> PA1KW >> >> > _______________________________________________ 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
