K3: Using 40m Loop for 10m
Locked
 
|
I use my K3 to participate in a daily 10m CW net (28.130, 7pm PST).
I've been experimenting with two antennas for the net: 40m full wave, vertically-oriented loop, relying on my KAT3 for a match, and a home-brew 10m rotatable dipole cut pretty close to resonate at 28.130.
When using the loop for operating on 40m, of course I get great matching without the KAT3. When using the loop for the 10m net, the KAT3 works hard, but it does provide close to a 1:1 indicated match.
When using the loop on 40m, I can vary the output from minimum to full (approx 120w). But when I use the 40m loop on 10m, the power out shows 50w max. If I maintain the power output control to indicate 100w, I get "Hi Cur" indications during a transmission that exceeds a minute or so. (These Hi Cur indications are never instantaneous in these situations, nor are they consistent.)
I'm sure there is some form of safety protection for the K3 transmitter, but I could not find documentation on how the transmitter might behave when it's connected to such a mismatched antenna, even with the presumed match using the KAT3.
Can someone educate me on this? I know my 40m loop is not supposed to do well on 10m. I was frankly surprised that the KAT3 matched it as good as it did!
Believe it or not, my ground wave signal for our local 10m CW net has been reported by the net control station as much better with the loop than it is with the 10m rotatable dipole. (Using the 10m dipole, I can see power out of 100+ watts, and don't get the Hi Cur warnings -- the signal just
isn't reported by most as being strong like the loop.) Any insight on this would be greatly appreciated.
73, Phil, WA7URV K3 #1206
_______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
|
|
Hi Phil
I think the first thing that occurs to me is: are you
feeding this loop with one coax and just switching between bands?
David
G3UNA
_______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
|
|
In reply to this post by Phil Westover
Hi Phil,
I have a lot of experience using 10M for VHF type contacts. You have to approach is as a VHF band. I asssume the stations are local to you and are not coming in on skip. That being the case you need to find out if the stations are vertically polarised. If so you will get good results using a vertical antenna. You could use your dipole as a vertical or an end fed half wave CB type antenna and resonate on 10M. Do not use your tuner to get rid of the mismatch - this applies to any antenna fed with coax. If you have a mismatch on the antenna you need to put the tuner between the coax and the antenna itself. If you want to use tour 40 M loop - and this will be too large to give a good space wave (ground wave) signal, you could feed it with balanced feeder into a balanced tuner ( or into your existing tuner with a balun). It will then tune on all bands from 40 M up, and may work to some degree on 80M. I used to use 10M for local contacts on FM and SSB in the 70s and 80s and the range, providing you get the antennas right is very good. Good to see 10M is being used in sunspot minima years. You never know when it will open up. Hope that helps 73 John G3YPZ David Cutter wrote: > Hi Phil > > I think the first thing that occurs to me is: are you feeding this loop with one coax and just switching between bands? > David > G3UNA > > > > I use my K3 to participate in a daily 10m CW net (28.130, 7pm PST). > I've been experimenting with two antennas for the net: 40m full wave, vertically-oriented loop, relying on my KAT3 for a match, and a home-brew 10m rotatable dipole cut pretty close to resonate at 28.130. > > When using the loop for operating on 40m, of course I get great matching without the KAT3. When using the loop for the 10m net, the KAT3 works hard, but it does provide close to a 1:1 indicated match. > > When using the loop on 40m, I can vary the output from minimum to full (approx 120w). But when I use the 40m loop on 10m, the power out shows 50w max. If I maintain the power output control to indicate 100w, I get "Hi Cur" indications during a transmission that exceeds a minute or so. (These Hi Cur indications are never instantaneous in these situations, nor are they consistent.) > > I'm sure there is some form of safety protection for the K3 transmitter, but I could not find documentation on how the transmitter might behave when it's connected to such a mismatched antenna, even with the presumed match using the KAT3. > > Can someone educate me on this? I know my 40m loop is not supposed to do well on 10m. I was frankly surprised that the KAT3 matched it as good as it did! > > Believe it or not, my ground wave signal for our local 10m CW net has been reported by the net control station as much better with the loop than it is with the 10m rotatable dipole. (Using the 10m dipole, I can see power out of 100+ watts, and don't get the Hi Cur warnings -- the signal just isn't reported by most as being strong like the loop.) > > Any insight on this would be greatly appreciated. > > 73, Phil, WA7URV K3 #1206 > > _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
|
|
In reply to this post by Phil Westover
>Believe it or not, my ground wave signal for our local 10m CW net has been
reported by the net control station as much better with the loop than it is with the 10m rotatable dipole. Phil, this is to be expected, ground waves are vertically polarized transmission modes. Your rotatable dipole is cross polarized for this mode. A simple vertical would probably work better yet. Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |