Posts Tagged ‘Elecraft KX3 QRP’
Another portable test of the BLT+ tuner
|KX3 operating on internal battery. What a fantastic portable rig.|
I took the BLT+ balanced line tuner out to the Excalibur antenna site to try it out on the doublet antenna that we put up last Saturday. This was the first test of that antenna (40m and 80m using a common feedpoint).
|BLT+ connected to open wire line (under the gloves) going to ta 40m Doublet at 65ft|
I used the BLT+ to tune the 40m/80m doublet. Balanced line antennas perform better with a tuner designed for balanced line and this was a good test for both the tuner and the new antenna.
|Portable shack, courtesy of three plastic chairs|
I quickly matched the doublet using the BLT+ using the lowest impedance setting which is also the most efficient. I was glad to see that the BLT SWR LED indicator is bright enough to be seen in direct sunlight. I was wondering about that but you can definitely tell when it dims even in direct sunlight.
AA4OO sitting back and listening to the QSO
The Doublet's feed line has not been brought to the shack yet so I was just sitting under the antenna. The open feed line is running along the ground for a bit which certainly didn't help the signal but we haven't installed the posts to carry the feed line over to the shack and I was too lazy to move the chairs far enough away to keep the feed line in the air.
In the foreground is some saw-grass common on the NC coast. I'm not sure why it's growing this far inland.
|Portable shack at the Excalibur antenna site... The Doublet is 65 feet above my head|
|Waiting my turn in the QSO... holding the Palm Single Paddle. BLT+ tuner in the chair to the right|
Five by Nine... QRP... How can it be?
I gave him reports as he switched back and forth from running barefoot ~75w to his amp ~500w. With his amp on he was an S9, running barefoot he was S8. So the amp gave him one additional S unit. In terms of hearing him I would have been hard pressed to tell much difference simply by volume. He was perfectly copyable without noise with the amp off.
We also did some tests with my station at reduced power (as if...) At 10w-12w output I received a S9 to S9+10. Reducing output to 5 watts netted me a S8 report and when I reduced to 1 watt (one watt) he was still able to comfortably copy me and I received an S5. So with my station at 1 watt and his running 500 watts we could still converse via SSB. Ladies and Gentlemen you don't need as much output wattage as you think you do.
He was running through a newly constructed homebrewed vertical while I was using my 80m OCF Dipole. We didn't discuss what sort of radial system he had installed, but the difference in antennas was likely the deciding difference in our stations. We were about 500 miles apart and his vertical probably had more low-takeoff gain than my dipole, or possibly more ground loss so I probably had better high angle gain on him for the short 500 mile skip. I think the take-away from this exercise is that the antenna is generally the key rather than transmitter power. If I can get 6 dB of gain from my antenna I have in essence quadrupled my effective radiated power. Quadrupled? Yes, Quadrupled effective output power.
Power and S-Units
- A Power Ratio: dB = 10 Log P2/P1
- A Voltage Ratio: dB = 20 Log V2/V1
You increase 3dB each time you DOUBLE your power
You increase 3dB each time you DOUBLE your power. So to gain one S-Unit you must quadruple your power.
Antennas offer the cheapest increase in dBNote the statement above "using the same antenna system". That's the key then isn't it? It's easier to get 6 dB of gain from an antenna than from wattage. A 40m doublet can offer significant directional gain especially when operated on higher bands. Now unless it's rotatable you will be at the mercy of the directionality of its lobes but if you have trees or tall structures you can very cheaply string up a few dipoles oriented in different directions and for far less money that a 500 watt amp (6 dB). If you can only have one wire antenna you may miss out on some DX in the antenna's nulls but you will have some stellar gain in the direction of the lobes. Of course rotatable yagis and beams are the best but now we are talking about real money again. I'm talking bang for the penny. You don't have to buy a wire antenna. Some Dacron rope or weed-eater line and some surplus insulated wire is all you need. You can even make your own feedline cheaply from electric fence wire and insulators.
We have a great hobby, but there are so many aspects of it that sound like common sense when they really are not... like increase your power.
Increasing power gains you very little compared to a better antenna systems. Put that in your 811A amplifier tube and smoke it !
That's all for now.
So lower your power and raise your expectations (or your antennas)
72/73 (Note: 72 is a common substitute for 73 among QRPers... as in "not enough power for 73")
Operating QRPI had the day off today and it was a beautiful morning. I decided to spend part of it at Lake Wheeler Park in Raleigh, NC operating QRP from a stone bench under a tall oak tree.
Can mean operating from a "Quiet Restful Place"
|rock 'n radio|
I threw a line over a tree using a throwing weight. I hit my mark the first time, untied the weight, tied on the end of the antenna, and hoisted the 31 foot end-fed up exactly where I wanted it with the feed point a couple of feet off the ground.
|31 feet of wire end-fed by a 9:1 balun.|
A kite string winder holds the throwing line
A metal stake with a bit of rope anchors the balun and the other end of the rope
|Another view of the end-fed with 9:1 balun, stake and coax|
|QRP operating position|
I called CQ on the 20m QRP calling frequency (14.060) and had a brief QSO with a lot of QSB (fading). I didn't hear much activity that early in the morning on 20m so I dropped down to 40m and worked the QRP calling frequency (7.030) and had my call answered right away. After that QSO another station jumped in there calling for a specific station so I moved on. 40m was busy. Every time I thought I'd found an open frequency someone would jump back in or if I called QRL? I'd get an R R.
The Palm key has a clip-on, magnetic base which I use to temporarily attach it to my clipboard when I'm not sending. When I'm ready to send I simply pull it off the clipboard and hold it in my left hand. As I noted in an earlier review of the Palm Single Paddle it can be used as a straight key if you turn it on its side. The long ragchew I had on 30m was with a gentlemen who sent me his SKCC number in the first exchange so I quickly turned off the electronic keyer in the KX3's and turned the Palm Single on its side. That station sent me a nice compliment on my straight key FIST; so the little Palm Single key can serve duty as a paddle into a keyer or (in a pinch) as a straight key. I far prefer to use my Kent Hand Key if I'm operating manual key but it's too big to bring along for portable operations and I can't quite picture myself trying to hold onto the giant Kent Hand Key with one hand whilst operating it with the other like I can the Palm Single.
|The Palm Single Paddle works great in portable operating positions|
|What could be finer than to be in Carolina in the Mooo-oor-ning|
|Enjoying the last nice days of our Fall... birds singing and morse code beeping|