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Author Topic: I hope I don't start a fight...  (Read 4622 times)

Posts: 130

« on: May 19, 2012, 09:02:09 AM »

I want to get into portable QRP fun and I honestly am seeking some reasoned opinions about which of the following two freqs. might work easier/more successfully for QRP.

I use a FT-450 as a base and portable rig. It is a great radio for me  but it is a battery eater when portable and it is a little heavy.

I have been looking at the reviews and comments about the MFJ-4520 and 4540 QRP radios. Size,weight and current draw meet my requirements and they are in my price range. I understand there are limitations as to being analog. I will be operating SSB with a 12v/10ah LiFePo battery and feeding a home brew buddi stick.

I commonly work 17 and 20 meters and just wonder if there is any advantage to choosing between 20 or 40 meters for QRP.

I realize that a radio like an Icom 703 or Yaesu Ft-817 would give me more options and yes I would like to have one but used they are double the price of the MFJ new.

So, any feedback on the 20/40 question will be appreciated.
« Last Edit: May 19, 2012, 09:22:46 AM by KJ4RQV » Logged

Posts: 1054

« Reply #1 on: May 19, 2012, 09:31:14 AM »

I would have recommended 30 meters, until I read the part about SSB. Personally, I like 40, but at times 20 is a better choice.  You have to look at the time of day you intend to operate, and the kinds of stations you (local or DX) you would like to work. Study up on propagation factors, throw in your own operating habits, and one of the two bands will clearly present itself.

Use your current gear and see which you are using the most. Whichever it is, go for that one.

Or, better yet, buy both radios and put them into the same chassis. It's been done before.

Also take a look at the radios being offered by Hendricks QRP kits. You might even save a few bucks and get quality to boot. Check for the MMR-40 kit and the BitX 20 (or 17) SSB/CW kit. The manuals and schematics are posted online for your perusal.

Good luck and have fun. Stew

Posts: 14499

« Reply #2 on: May 19, 2012, 10:24:09 AM »

There is no set answer. It depends on your personal preferences and operating habits. If you like to work DX and you operate mostly during daytime hours then 20M would be a good choice. The Buddistick antenna will also be more efficient on 20M than it will on 40.

On the other hand if you operate mostly in the evening/night hours then 40M is likely to have more activity. With QRP and a Buddistick you aren't likely to work a whole lot of DX on 40M however.

My experience is that with QRP on either band CW will yield a lot better results than SSB.

Bob  AA4PB
Garrisonville, VA

Posts: 17484

« Reply #3 on: May 19, 2012, 01:01:02 PM »

I think I'd agree:  in my experience, 40m may be easier to make contacts, and
they will be more local.  20m will give you longer contacts, but they will be
more dependent on the time of day.

It partly depends on your antenna:  as AA4PB said, your antenna efficiency
will be higher on 20m.  On 40m the losses in coils and connections become
more important:  it is possible to make a reasonably efficient short antenna,
but it takes some work, and simpler short antennas will tend to be less

But on the other hand, if your antenna is horizontal and relatively close to
the ground (less than about 20' on 20m) then much of the radiation will be
at high angles that aren't reflected back to Earth by the ionosphere, so
the effective efficiency is low because much of the radiation is wasted.
For the same low height, a 40m signal may be reflected back, which is why
it is better for local coverage.

If you can get your antenna 30' in the air, or can operate from the top of
a hill, or by the ocean, 20m can make contacts around the world.   But
if you're on the flats with the antenna only up 8', you may find that more
stations can hear you on 40m than on 20m, even if they aren't as far away.

Not that you can't make contacts with a low antenna.  I used a wire dipole
with the center propped up about 3' off the ground and had a delightful chat
with a station in Tasmania on 20m SSB with my Ten-Tec Argonaut at 2 watts. 
Actually I was in Western Australia at the time, so he was only 2500 miles away,
and my tent was on a rock ledge by the ocean.  When operating from places
with a low ham population density (such as Alaska and Australia), 20m is
often a better choice.  But in the US, I mostly use 40m because there are
plenty of local stations around.

One thing I do recommend is to use a full-sized wire antenna whenever possible
rather than a shortened antenna.  You can use quite small wire, making the
whole antenna much lighter, so that a fishing pole can elevate the center up
much higher than would be practical for a heavier antenna.  The efficiency
is higher, too.  Overall, height is going to make a big difference in your ability
to work stations, particularly on 20m, and the wire dipole over a tree branch,
or held up by a telescoping fiberglass pole, gives the most effective antenna
vs. cost and weight of any that I've tried so far.

Good luck!

Posts: 12629

« Reply #4 on: May 19, 2012, 04:23:08 PM »

If I was hard core serious about portable QRP I would get a KX3. I was just looking at one at Hamvention today.  Nice rig with output variable from .1 to 10 watts. Draws 150ma on standby. It can use 8 AA batteries in a built in compartment for self powering (you could get some 2600 ma NiM batteries and get some decent run time on very low power. While it cost more than a 817 is it a much better rig receiver wise and better than 450 too.

Ham since 1969....  Old School 20wpm REAL Extra Class..

Posts: 130

« Reply #5 on: May 21, 2012, 05:16:41 AM »

Thanks to all of you.

I would sure love to have the new Elecraft but the price is just too high for my hobby budget.

I did play around on 40 meter at 8 watts fed into my delta loop home antenna  and made several contacts including the special event station at the Dayton Hamfest and got strong signal reports.

Good advice from all, thanks.

Posts: 1003

« Reply #6 on: May 23, 2012, 11:49:56 AM »

You might consider a Heath HW-8 - four bands, 80,40,20,15, and the price is reasonable. They're not new, but they were built as kits, and support is available.
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