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Author Topic: New to QRP  (Read 5625 times)
KC5IIE
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Posts: 23




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« on: May 24, 2010, 06:50:32 AM »

Howdy folks, Im ready to take the qrp portable plunge! Ive got my 817, manual tuner and a 12v/7.5maH battery ready to go. My first question is about charging my battery. I see cheapo chargers at Harbor Freight (about $10), are these sufficient for light duty work? Second, I have a couple options for antennas, I have Workman hamsticks which I can mount on a painters pole with a counterpoise, probably wont require a tuner. Or, I have a multiband dipole fed with 450 ohm ladder line that I can run thru a tuner. My concern is losing too much rf power in the tuner. Ant exprience using such a dipole arrangement while running low power? The antenna works great with 50 watts. Thanks for any advice, 73's

Chris  KC5IIE
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WX7G
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« Reply #1 on: May 24, 2010, 08:49:34 AM »

The dipole would be my choice. The power lost thru the tuner is a percentage of the total power. If it dissipates 10 watts when running 100 watts it will dissipate 0.5 watts when running 5 watts.

The easy way to work QRP is to call only strong stations. With most stations running 100 watts your signal will be 13 dB weaker (about 2 S-units) at their receiver than their signal is at your receiver.
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W3JJH
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« Reply #2 on: May 24, 2010, 11:28:23 AM »

The portable antenna that I use the most is a 135 ft dipole fed with ladder line.  If I can't get both ends up, I use it as an inverted vee.  Another handy simple antenna is a 24 ft sloping wire operated against a 24 ft wire laid on the ground as a counterpoise.  This works well with a tuner on 40, 30, and 20 m.
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WB2WIK
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« Reply #3 on: May 24, 2010, 02:37:01 PM »

Howdy folks, Im ready to take the qrp portable plunge! Ive got my 817, manual tuner and a 12v/7.5maH battery


That's a really small battery!  It must last about 15 seconds. Tongue

Assuming you meant "AH," the cheapie 12V battery charges intended for motorcycle batteries and such generally work fine.  Charging at 750mA initial rate for about 1 day will charge it up from quite depleted to "full," and the charge current will taper off as the battery charges up.

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KC5IIE
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« Reply #4 on: May 24, 2010, 03:27:59 PM »

Duhhh, yes it is a 7.5aH battery. Good stuff, guys, I really appreciate it. I hope to set up a practice run in the backyard this weekend,
we'll see how it works! 73's

Chris  KC5IIE
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WB8YYY
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« Reply #5 on: May 24, 2010, 07:01:31 PM »

Chris

sounds like you are ready for adventure - and already you have read the 'full size' antenna is the bigger factor, not the tuner.  I am impressed you have a manual tuner! 

Do assess how long your battery will last with that rig on receive.  Let's say its 1 amp (look it up its only a guess) -- 7.5 amp-hours / 1 am = 7.5 hours.  ok less if you transmit some - and keep in mind the battery will not supply enough voltage at 0 amp-hours, so you really have a bit less operating time - but its good for a short outing.  someday if you really like portable operating, you may wish to also have a simpler QRP rig that uses only 10's of mA on receive.  meanwhile enjoy what you have. 

Curt
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KC5IIE
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« Reply #6 on: May 25, 2010, 04:01:43 AM »

Thanks for the tips Curt, yes, I want to do some trial runs in the backyard to see how long the battery lasts and to see how
the old manual tuner works with low power (I admit, Im spoiled in the shack with an autotuner). Ive read the 817 is a
little battery guzzler (sort of), but its a very nice rig. We'll see how things develop, need to dust off the key and start
practicing CW again. 73's

Chris  KC5IIE
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WB2WIK
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« Reply #7 on: May 25, 2010, 06:41:04 PM »

The 817 gobbles up more power than the internal batteries can handle for very long, but with a 7.5 AH external battery it will last a long time -- about 10-20x longer than with the internal batteries.

I have an 817ND and have used it for a full week of operating intermittently (maybe an hour a day or so) with a 7.5AH gel cell, no problems.

The work is all done by the antenna!  For a lot of portable ops, I just toss a wire inverted vee into a tree and use a manual tuner with it to cover 40 through 6 meters.  The antenna "legs" are 25' long each (50' long overall) so it's not resonant anywhere, but I use 300 Ohm twin lead as a transmission line and a tuner with a good balun in it, and it's worked the world from some good locations.

Have fun!
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VE3WMB
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Posts: 282




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« Reply #8 on: May 25, 2010, 09:24:48 PM »

Chris :

I recommend that you check out :

http://www.ka7oei.com/ft817_pwr.html

There are some very good tips to make the FT-817 less of a power guzzler. Most  are
probably not obvious to you, such as using the front antenna connector (BNC) rather
than the rear (using the rear antenna connector requires a non-latching relay be
energized, which draws an additional 30mA).

Also be aware that you don't want to discharge your battery below 10.5v even though the
FT-817 is quite happy to keep going at that voltage. A 12V SLA battery is considered fully
discharged at about 10.5V .. it is generally best to derate the battery capacity by 50% so
assume that you can draw about 3.5 AH from your 7.5 AH battery.

Best of luck and have fun !

Michael VE3WMB

Thanks for the tips Curt, yes, I want to do some trial runs in the backyard to see how long the battery lasts and to see how
the old manual tuner works with low power (I admit, Im spoiled in the shack with an autotuner). Ive read the 817 is a
little battery guzzler (sort of), but its a very nice rig. We'll see how things develop, need to dust off the key and start
practicing CW again. 73's

Chris  KC5IIE
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AI4HO
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Posts: 80




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« Reply #9 on: May 29, 2010, 01:16:21 PM »

Chris,

   Looks like you've got a good handle on things, the FT-817ND is a great little rig, had one a couple of years ago, but as others have said, it does eat up your power.  I was forced by a situation to sell my 817 less than a year after I bought it, however the beginning of this year I found a 2 week old IC-703+ for a great price.  I have found that this isn't as power hungry as my 817 was, but there are no internal batteries on this, but I also have a 12v-7.5AH gel cell that will go all day and night, and my preferred antenna is either a dipole or my Buddipole, great set up, I've gone to one of our local parks and set up and just play radio for a couple of hours.  You are not the only one that needs to brush up on his CW skills, I've gone far to long and not used it, but am in the process of changing that.  Hope to work you one day, 817 -703, dipole to dipole or dipole to Buddipole.


73 de Mark
W3LZK
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KU2US
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Posts: 74




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« Reply #10 on: June 24, 2010, 04:58:10 AM »

Hey, check out the QRP multi-band end fed long wire by Par Electronics. It is cheap, light and small, and they work great! I have 2 of the mono-banders for 20m and 40m. Also check out the reviews on Eham. I am not connected to Par in any way, I just swear by these antennas. Last month I bagged Hong Kong with 200 watts with one of these baby's. You can set it up any way you want and it will not affect performance. As far as I am concerned, this antenna is the holy grail of QRP..












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K5LXP
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Posts: 4448


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« Reply #11 on: June 24, 2010, 05:36:20 AM »

I wouldn't recommend a cheap charger for your gel cell unless you don't mind replacing the battery more often than you need to.

Gels especially are senstive to charge current, voltage, and time.  A motorcycle battery charger will likely give it too much current at the beginning, and not enough voltage at the end.

Get a charger made specifically for gel batteries.  There is a difference, and it matters unless you have a ready source for replacement batteries. 

Leave the hamnsticks at home.  When you're running QRP, the antenna is everything.  Just about any wire antenna will be pretty efficient, so I would focus on coming up with a wire configuration that works best for your style of operating.  The PAR is a good one, as would be a balanced doublet and a tuner.  Nothing wrong with resonant dipoles, either.


Mark K5LXP
Albuquerque, NM
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KC5IIE
Member

Posts: 23




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« Reply #12 on: June 25, 2010, 07:07:57 AM »

Thanks for the comments, glad this thread still has some life, yes, I contacted Dale at Par a couple weeks ago, he replied they were currently focused on Govt contracts but would be resuming ham production for a week in July, I plan to nab a couple including the 10/20/40 end fed. Ive discovered my multiband dipole is pretty difficult to deploy in the field. I used to have it permanently installed in the backyard where it did just fine. However, the wire size and the 450 ladder line restricts where
I can deploy it (I used 14 gauge wire I purchased at Lowes, and a 17 ft run of ladder line). I think I need something more lightweight and flexible for the field... Yes, using the hamsticks has not netted any contacts with 5 watts, QRO works though.
So far, my $15 charger seems to do the job, Ive only charged it a couple time though. 73's everyone, I'll be on QRP portable in the backyard this weekend for Field Day!

Chris  KC5IIE
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K5LXP
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Posts: 4448


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« Reply #13 on: June 25, 2010, 11:49:58 AM »

Sounds like you're on your way Chris.

Just a quick data point, you don't need really heavy duty wire for portable antennas.  In fact, you can go with wire much thinner than you would expect.  Portable antennas typically don't go through the hardship that a more permanent installation would have to endure.  It's not likely you'll be operating portable during wind, and icing conditions.  My favorite antenna wire for QRP portable is 26 gauge silver plated stranded teflon, which is very strong for it's size.  You can fit a large antenna in a ziplock sandwich bag, which is how I transport them.  I usually don't use feedline either, basically I launch the antenna right from the output terminals of my portable tuner and use a coax jumper from the tuner to the rig.

It may take a while to come up with a configuration that works for you but keep after it and continuously refine your setup.  It's all fun, regardless.


Mark K5LXP
Albuquerque, NM
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