[Elecraft] K3 and XV144 strange behaviour
I noticed a strange behaviour during the last IARU VHF Contest last weekend. With our team we managed to have a first field test of the rig coming for our experience with the K2/xv144 MHz combination the expectations were high. The setup was composed by the K3 and a XV144 transverter, plus a Power amplifier, a preamplifier at the antenna (with some 30 mt of 1/2 cellflex line) and two stacked 19 elements Log Loop Yagis. The switching sequence was controled by an external sequencer drived by a foot pedal. On the receiving side the combo was wonderful, the dynamic range allowed us to manage very well in the pretty crowded 2 mt band. But we had some troubles mainly on TX. Let say that our P.A. needs to be drived with circa 7/10 Watts at maximum (depending on the mode, SSB or CW). It's made from 2 x 4CX250B in push-pull configuration. So I tuned the transverter to go from a range of 1 W (with -10 dBm drive from the KXV3 module) to a mazimum of 10 W (with 0 dBm of drive). Things have worked pretty smoothly most of the time, but on a few occasions, we noticed a sudden loss of output power from the transverter (and from the P.A. of course). Turning the K3 off and on again the transverter didn't power up. The XV144 label on the front panel flashed for a brief moment and then stayed off. Changing band to HF and back again on 144 MHz (TRV1) and the XV144 module powered up again. Not always on the first try. Once powered up most of the times the output power was correct, but occasionally we had to do the procedure three or four times before coming back to normal functioning. Any clues of the reasons of this behaviour??? 73 de Giulio IW3HVB ___ 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 and XV144 strange behaviour
Before you ask... Firmware Revisions: MCU 2.34; DSP 1.89. 73 de Giulio IW3HVB. ___ 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 and XV144 strange behaviour
On receive we had persistent problems with people using lesser receivers and similar transmit power not being able to copy us because of QRM. DLs especially. We heard many very strong signals but none excessively wide. We also had system problems though not the same, or at least the same but partly fixed. In our case the 9-way D connector was at fault, unless fully screwed in it was found to not be making a good contact. Fully screwing it in fixed that of course, nothing to do with the K3. Our main K3 related problem was the inconsistent power output. We were also using a pair of 4CX250Bs, parallel rather than push pull. To avoid over drive splatter, the amplifier trips out if any significant grid current occurs. The power spikes I have noted before made tuning up the drive with the PA on impossible. The correct drive was set, in incremental steps with the spike dealt with by keying with the PA off for the first transmission, then enabling the PA and seeing if the drive was sufficient. Once set the power would not stay fixed, it would sometimes drop by maybe 2-3 dB. Just adjusting the power one step up or down brought it back but with the usual initial spike that would on occasion trip the amplifier protection. After a couple of overs the power would drop back again. While setting up we also did some transmit cleanliness checks with local stations. The K3 + XV144 at about 7W output driving the pair of 4CX250Bs was reported to be exceptionally clean with very good audio. Considering this, the K3 plus XV144 while probably the best combination I have ever come across on receive is not ready for use on transmit just yet because of the ALC issue if you use a sensitive amplifier. One other minor point, with large chunky VHF coaxial relays, the 20mS TX delay is not quite long enough, but still much better than those rigs with no TX delay at all! You probably still need a sequencer. Mike Giulio Pico wrote: Before you ask... Firmware Revisions: MCU 2.34; DSP 1.89. 73 de Giulio IW3HVB. ___ 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 -- View this message in context: http://n2.nabble.com/K3-and-XV144-strange-behaviour-tp1079275p1079315.html Sent from the Elecraft mailing list archive at Nabble.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 and XV144 strange behaviour
Considering this, the K3 plus XV144 while probably the best combination I have ever come across on receive is not ready for use on transmit just yet because of the ALC issue if you use a sensitive amplifier. Next time you set this up and *after* you have the drive set, set CONFIG:TX ALC to OFF. Then see if you have the same problem. If you are running SSB, you might also try setting CMP to 0. 73, Lyle KK7P ___ 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
