Tuner losses
Locked
 
|
I bought the KAT100 tuner as a convenience item
and did not think it would be as efficient as other tuners in the shack. I judge the merit of tuners by measuring the RF current in the ladder line going to my 234 foot open loop around the house. It is a beast to feed on 160 and 40 meters, and much easier on all the other bands. I have the actual conjugate impedance measurements on all the bands around here somewhere, but lucky for the group, I can't find my data at the moment. I have measured current using thermocouple and home- built clamp-on ammeters. My Palstar AT1500BAL is a no-compromise balanced output tuner. There is a 1:1 balun on the input and the tuner consists of an L circuit for each side of the feedline. It is configurable for high and low impedances, with very heavy duty relays changing the variable capacitors from the input of the inductor to the output. It has beat out the 300 watt version of the Johnson Matchbox. I have not had access to the KW version, but an article by Frank Witt in QST several years ago showed the 300 watt version to be superior to its big brother. The Palstar has also beat my MFJ KW tuner that I have used floating from ground with a 1:1 balun at the input. There was no balun at the output and the MFJ was more efficient in that configuration than using the built-in 4:1 balun. (See the ARRL Antenna Compendium Volume 2, page 172, "Some Additional Aspects of the Balun Problem.") I was quite surprised to see the KAT100 tuner to put out essentially the same currents on all bands as the Palstar balanced tuner! So a convenience it is, but also it is a good tuner! I have also used it, at Wayne's suggestion, to feed a portable 23 foot vertical with elevated 23 foot radials fed with 300 ohm ladder line and 1:1 balun on the output of the K2. This is antenna is used on 40 through 10 meters and has won me thousands of QSO's. There I have measured current at the base of the vertical radiator. The Elecraft tuner beat my manual 300 watt MFJ tuner feeding the antenna directly at the base. It also outperforms the LDG RT-11 also at the base of that vertical with no feeline between the tuner and antenna. I still use the giant Palstar as the KAT100 won't work with my Sierra or my KW Japan Radio linear! For the K2 barefoot, the KAT100 can't be beat, as far as I can see. Andy W9NJY Milwaukee K2 ser 2651 _______________________________________________ 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 |
|
|
Bill,
I am using an LDG 4:1 balun between the KAT100 and the 450 ohm line that feeds my loop on 40 through 10 meters. It's very similar to the Elecraft 4:1 balun. On 80 and 160, because the conjugate impedance is low, I use a 1:1 balun. I bought it as a kit from Coil Winding Specialists. I would have bought the 4:1 balun from Elecraft, but at the time I first hooked this up, they didn't offer one. With the vertical, I hook the output of the KAT100 to the 1:1 balun via a couple feet of coax. Then I have about 25 feet of 300 ohm ladder line from the output of the balun to the base of the vertical. One side of the 300 ohm line is connected to the radials and the other to the vertical element. I also have huge 4:1 and 1:1 baluns from CWS. They are rated at 10 KW. I'm not sure how they came up with that spec, but the ferrite cores are huge and the wire is heavy gauge. There are big ceramic standoffs for the ladder line. At the 100 watt level, these don't offer any advantage over their smaller counterparts. Calculating true tuner efficiency is complicated as a load that represents an SWR of 8:1 may be composed of all radiation resistance and no reactance, as in a resonant, short antenna, or it may be a 50 ohm antenna with a lot of reactance that's being operated way off its resonant frequency. That's why these discussions of tuner efficiency never end. Some tuners are better with different kinds of mismatches. Anyway, I've had great success with the KAT100 into my particular loads, and I like that it doesn't stop tuning till the SWR is at, or very close to 1:1. And most of all, I like the good current measurements I get. After all that, the QSO's just flow. Let me know if you have any other questions. 73, Andy ----- Original Message ----- From: "Bill Strong" <[hidden email]> To: <[hidden email]> Sent: Saturday, May 14, 2005 9:50 AM Subject: Re: [Elecraft] Tuner losses > Hi Andy, > > I tried to post the message below after reading your very interesting > comments. I don't think I did it correctly so I am emailing directly > too. > > Thanks, > Bill WA5KPE > > > I use an SGC 211 which sits on my desk beside my K2/100. It feeds 450 > ohm ladder line directly to my Cobra Ultralite 140' doublet. This works > well enough except that the 211 will constantly retune if not disabled > by turning it off. I also own the MFJ 974H balanced tuner. The 211 gets > better matches. > > I have ordered the KAT100 and the BL1 4:1 balun which will be here in 3 > days. My question is what balun are you using between the KAT100 and > your loop? Also, do I understand correctly that with your vertical you > are using the balun between the K2 and the KAT100 or is the 1:1 balun > between the KAT100 and the vertical? > > Thanks, > Bill Strong WA5KPE > Hattiesburg, MS > K2 #4454 > > -------------------------------------------- > Bill Strong's Coastal Images > Bill Strong's Eclectic Mississippi Photo Tour http://www.phototour.com > > > _______________________________________________ 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 |
|
|
Charles,
Thanks for correcting me. Sorry that it's been a while since I looked at the Elecraft balun on their web page. I forgot that it was a current balun. 73, Andy ----- Original Message ----- From: "Charles Greene" <[hidden email]> To: "Andrew Catanzaro" <[hidden email]>; <[hidden email]> Sent: Sunday, May 15, 2005 6:57 AM Subject: Re: [Elecraft] Tuner losses > Andrew, > > I beg to differ that the LDG: 4:1 balun and the Elecraft 4:1 balun are > similar, or even close. The LDG 4:1 balun is a voltage balun. I don't > have one, but I have its schematic. The Elecraft 4:1 balun is a current > balun, plus the fact that it is wound on a binocular core. The core > materials are different. If fact, the only similarity is that both are > 4:1 baluns. The major difference between a current balun and a voltage > balun is the frequency coverage. _______________________________________________ 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 Andrew Catanzaro
Andy,
I want to give you a follow-up. I built the KAT100 in less than three evenings and it is a wonder to me in both its design and operation. I built the BL1 in the 4:1 configuration. I get a 1.1:1 or less match on all bands except 15 Meters which is about 1.5:1. I find that the balun gets hot enough to fry eggs on 40 meters (even at 50 watts with SWR of 1.0:1), mildly hot on 30 meters, cool as a cucumber on 20 meters (even at 100 watts), and slightly warm on 17 meters. I guess that on 40 meters the balun is at a current node. The feedline is about 100 ft long on the 140 ft Cobra Ultralite 80 doublet antenna. I don't know that I want to get into trimming the feedline as I may affect 20 meters. I am able to make contacts on 40 meters although I would assume I am operating at reduced efficiency. The BL1 when very hot does not desaturate and make the SWR rise above 1.0:1. I want to stay with 300 or 450 ohm ladder line so I may put another antenna up for 40 meters. I manually disconnect the antennas outside the house when they are not in use. Our area has a lot of thunderstorms. I guess I can buy a heavier duty balun from DX Engineers; however, I notice that DX Engineers has a new multiband antenna for sale which is fed with ladderline along with one of their big baluns. I am going to look into it. I ordered another BL1 which I am going to build in the 1:1 configuration. I want to see what if any difference this might make before I decide whether or not to get a bigger balun and/or another antenna. Thanks for your help, Bill WA5KPE Hattiesburg, MS K2 #4454 -------------------------------------------- Bill Strong's Coastal Images Bill Strong's Eclectic Mississippi Photo Tour http://www.phototour.com _______________________________________________ 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 Bill, I recently built a KAT100 and 4:1 BL1 also (3 evenings too!). I
have a 160/80/60m trap dipole in ANT1 and a 40m doublet via the balun in ANT 2 for the other bands. This gives me instant QSY on ten bands. Like you, by coincidence, I find the balun gets very hot on 40m. What I plan to do is experiment by putting some L (tapped coil) across the balun on the balanced side to cancel out some of the reactance on 7MHz. (I've tried adding C but that was going the wrong way as it didn't help). I think doing this should reduce the 7MHz balun losses, and I suspect won't effect the higher bands too much. 73 Fraser G4BJM #4368 >From: "Bill Strong" <[hidden email]> >To: <[hidden email]> >Subject: Re: [Elecraft] Tuner losses >Date: Fri, 20 May 2005 23:09:13 -0000 > >Andy, > >I want to give you a follow-up. I built the KAT100 in less than three >evenings and it is a wonder to me in both its design and operation. > >I built the BL1 in the 4:1 configuration. I get a 1.1:1 or less match on >all bands except 15 Meters which is about 1.5:1. I find that the balun >gets hot enough to fry eggs on 40 meters (even at 50 watts with SWR of >1.0:1), mildly hot on 30 meters, cool as a cucumber on 20 meters (even >at 100 watts), and slightly warm on 17 meters. I guess that on 40 meters >the balun is at a current node. The feedline is about 100 ft long on the >140 ft Cobra Ultralite 80 doublet antenna. I don't know that I want to >get into trimming the feedline as I may affect 20 meters. I am able to >make contacts on 40 meters although I would assume I am operating at >reduced efficiency. The BL1 when very hot does not desaturate and make >the SWR rise above 1.0:1. > >I want to stay with 300 or 450 ohm ladder line so I may put another >antenna up for 40 meters. I manually disconnect the antennas outside the >house when they are not in use. Our area has a lot of thunderstorms. > >I guess I can buy a heavier duty balun from DX Engineers; however, I >notice that DX Engineers has a new multiband antenna for sale which is >fed with ladderline along with one of their big baluns. I am going to >look into it. > >I ordered another BL1 which I am going to build in the 1:1 >configuration. I want to see what if any difference this might make >before I decide whether or not to get a bigger balun and/or another >antenna. > >Thanks for your help, > >Bill >WA5KPE >Hattiesburg, MS >K2 #4454 > _________________________________________________________________ Be the first to hear what's new at MSN - sign up to our free newsletters! http://www.msn.co.uk/newsletters _______________________________________________ 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 |