QRP Operations

[KC0WTS]

One of the local clubs is having a qrp kit "extravaganza" if you will. We're building the rockmite, a .5 watt qrp kit make by small wonder labs. My question to the qrp elmers would be what would be a great qrp antenna that also would be extremely portable and easy to take down and set up. Also, what do you think about these antennas for QRP operations?

Vertical (http://www.mfjenterprises.com/Product.php?productid=MFJ-1640T) Dipole (http://www.mfjenterprises.com/Product.php?productid=MFJ-2240)

[VE3MPG]

Have a look at the PAR Electronics End Fed dipoles. They have a qrp version for 10m, 20m and 40m that is extremely portable and you can use up to 25 watts with it. I own 3 of the PAR antennas and they work like gangbusters. I have a 30m and a 40m up permanently - solidly built, rugged and stealth so they won't bother the neighbours and easy to put up in the field.

Here's the link:

http://www.parelectronics.com/end_fedz.htm

73,

Bob VE3MPG
http://ve3mpg.blogspot.com/



One of the local clubs is having a qrp kit "extravaganza" if you will. We're building the rockmite, a .5 watt qrp kit make by small wonder labs. My question to the qrp elmers would be what would be a great qrp antenna that also would be extremely portable and easy to take down and set up. Also, what do you think about these antennas for QRP operations?

Vertical (http://www.mfjenterprises.com/Product.php?productid=MFJ-1640T) Dipole (http://www.mfjenterprises.com/Product.php?productid=MFJ-2240)

[W0IS]

I have a piece of coax with alligator clips on the end. I usually use this to set up a dipole for whatever band I'm interested in. It's best to get it as straight as possible and as high as possible, but a dipole is very forgiving. I've operated quite successfully with the antenna draping over trees, zig-zagging, etc.

I simply use the cheapest available wire. Often, this is speaker wire from the dollar store, or steel wire from the hardware store. Depending on what I use, I either save it for re-use, or just throw it away when I'm done.

Depending on what's available, you can run the antenna in a straight line, as an inverted vee, or even as a non-inverted vee. The alligator clips give a lot of flexibility. If you can't run a dipole, you can use it for a vertical or inverted L.

For measuring, I often use picnic tables, which are usually 8 feet long. For each 40 meter element, I measure 4 picnic tables, plus about a foot. 20 meters is 2 picnic tables plus a few inches.

I can generally be on the air within five minutes of starting to think about where the antenna can go.

[KB9BVN]

One of the local clubs is having a qrp kit "extravaganza" if you will. We're building the rockmite, a .5 watt qrp kit make by small wonder labs. My question to the qrp elmers would be what would be a great qrp antenna that also would be extremely portable and easy to take down and set up. Also, what do you think about these antennas for QRP operations?

Vertical (http://www.mfjenterprises.com/Product.php?productid=MFJ-1640T) Dipole (http://www.mfjenterprises.com/Product.php?productid=MFJ-2240)

I have always used a dipole when I am out QRPing from the wilds....BUT...a whole lot of people swear by the End Fed Half Wave. You'll need to build up a little tuner for the EFHW though. Strictly HOMEBREW though. You can make a dipole for pennies.

http://www.vk2zay.net/article/115

The Rockmite is very cool. I had one for 20m and 40m for awhile...traded them for something else...and now I'm building PIXIE's.

Have fun

[K0RGR]

The endfed halfwave is a good choice. Here's a buddy of mine doing some serious QRPing from a local park:

http://www.youtube.com/watch?v=BUeJOuu5oUE

[DL7GEM]

When you are investing some effort in building your rig, just go the extra mile
to also build your antenna. For QRP most commercial antennas
are overkill -- excepting maybe beams, which are a bit harder to build.

I am using Up and Outer antennas for 40 and 30m. That's basically a dipole in an
L-configuration. When the antenna is resonant, the impedance can be tweaked to
50Ohms by adjusting the angle between the two legs. Another variation on the dipole
theme is the inverted vee which might be better for /p operations, because it needs
only a single anchor point.

I've built my Up and Outers from cheap twin-lead speaker cable, no need to get special
antenna wire.

Since getting all of the energy from the TX into the air, I'd go for a resonant
antenna. The shorter the antenna gets, the less efficient it will be.

Marcus -- DL7GEM

[K9ZMD]

A couple of posts have already mentioned that you can build a dipole for pennies. I'll be very blunt. If you are using a 500 milliwatt transmitter, you do NOT want either of those two antennas that you asked us to comment on. Neither of them will hold a candle to a simple dipole made of scrap wire, any kind of wire that you can find. Add a little RG-58 coax for a transmission line, and an SO-239 coax jack at your feed point, and you have an antenna that you can roll up & stuff into your pocket. No sweat to carry for portable operation, and if you somehow loose it, you've only lost pennies. In case you missed the point, this el cheapo approach will run circles around either of the two antennas that you were thinking about buying. 73

Gary, K9ZMD/6

[W4CBJ]

K9ZMD is correct. Use any wire that you have handy, I have used almost everything...solid, stranded, AWG 10 thru 28...Copper, steel, aluminum...Some folks think you must have an EXACT match, that is 1:1 VSWR. Bull, SWR 2:1 will work OK, too. Long live dipoles and end -fed long wire antennas. Try it and like it. 73 Joe W4CBJ

[KC0WTS]

Thanks for the comments. I think I'll be visiting radioshack instead of mfj's website.

[W1YB]

Thanks for the comments. I think I'll be visiting radioshack instead of mfj's website.


I doubt RS will have anything profound...

If your 'club' is building QRP rigs there must be someone who has the very small amount of oarts required to build a resonant dipole for your band of choice. A 'tuned tank circuit" will do wonders for an EFHW...

[AI3V]

I wouldn't even bother with regular 50Ω coax and fittings, Some cheap 300Ω twinlead,( the clear stuff you sometimes see for indoor use) and a balanced output ATU, If you plan on a dipole antenna.

If you are thinking about a vertical, or end fed antenna consider NO feedline, Just a l-network ATU built right into the rig.

In either case I would also reccomend a FULL SIZED antenna.

Rege

[KB9BVN]

This place might give you some good ideas as well.

http://www.qrpedia.com

[VE6WTF]

SIMPLE SIMPLE SIMPLE

QRP is all about simple rigs,
So why shouldnt the antenna be the same?

Half wave Dipole for 20m
And an Inverted Vee for 40m

cut for the best SWR you can possibly get.
works great for QRP, But when the band conditions call for it, I will hook up the TS-140S to them THEN its playtime!

[W4CBJ]

Best and cheapest source of supply for 'antenna' parts...is the "ANTENNA" store i.e, Home Depot, Lowe's or similar building suppy stores. 73 Joe W4CBJ

[W1YB]

This place might give you some good ideas as well.

http://www.qrpedia.com

Thanks for the link. That tank circuit for the 20 M EFHW is just a jewel!!

73 de W1YB

[KC4YLV]

Best and cheapest source of supply for 'antenna' parts...is the "ANTENNA" store i.e, Home Depot, Lowe's or similar building suppy stores. 73 Joe W4CBJ

1/4 mile electric fence wire turned into a decent radial field and HF dipoles - $4 on off-season clearance (nobody puts up fences in dead of winter)

10 foot chainlink fence top rails for masts - $11.99 each

PVC for VHF yagi booms (keep 'em short) - $3 for a 10 footer? cheap

Copper pipe turned into VHF J-poles - $10/10 foot piece

1/4" copper water line for 2m halos - $10 for 20 feet




By Jove, you're right!

:D