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Author Topic: QRPp // HF Morse at LESS Than One Watt  (Read 2966 times)

RadioRay

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QRPp // HF Morse at LESS Than One Watt
« on: September 17, 2014, 08:10:52 AM »
I was just reading through an older thread where Gil and I were in our regular (uh, semi-regular...) sked and for fun when I asked him to reduce power to one Watt, he instead turned it down all the way to his lowest setting of 100 milliWatts (1/10th of one Watt).  We continued the conversation.  Weak - yes, but quite copyable in Morse code at 100 milliWatts, or WAS it?  I was JUST re-reading that posting when my Ethiopian Harrar espresso charged engineer brain caught something I had glossed over before: Gil's feed line to the 1/2 wave wire antenna was (still is???) 50 feet of RG-178 coax.  A quick look at the spec sheet says that at that frequency, there is a loss of roughly 3dB in 50 feet of BRAND NEW RG-178 coax: reducing his power into the antenna tuning unit by HALF.  So, in actuality, he was radiating at BEST 50 milliWatts.  Yes, 1/20th of a Watt for well over 800 miles of communication. 

A legal CB radio can emit 100 times more power (5 Watts) than Gil was that day ( 50 milliWatts erp).


THAT - is something to think about. A quiet location, wire antenna, low noise receiver with good filters are all things which make this possible. We are using home made kit radios - at best.  5 Watts CW into a good antenna is usually more than enough to communicate reliably, unless your receiving station is in a noisy RF location - like many cities are.  Even then, there are phasing noise cancellation gadgets that go into your antenna line before the rig which make a HUGE difference!  This is not a filter for the noise, instead it nulls the noise before it reaches your receiver. I have one that I used when the landlord's daughter was dating some metro-sexual who rode an electric mini-motorcycle and put a battery charger at her house.  That cheap charger generated more electrical interference than an entire Chinese army electronic warfare battalion could muster. My noise cancellation device allowed me to carefully NULL most of the hash generated by his battery charger. Her parents should have eliminated him, but that is another story.

Some fun links:

http://youtu.be/-EOvZVAam9E   Splinter 250 mW Transceiver

http://aa1tj.blogspot.com/2010/12/solidarity.html  40 mW using Soviet mini-tubes!

More Code: It's a survival skill.


de RadioRay ..._  ._
« Last Edit: September 17, 2014, 08:57:56 AM by RadioRay »
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

KK0G

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Re: QRPp // HF Morse at LESS Than One Watt
« Reply #1 on: September 17, 2014, 09:11:17 AM »
So, are you saying that QRP actually works? 8)

It's been close to a year now since I sold my fire breathing, 100 Watt, Kenwood TS-2000 and replaced it with a pipsqueak 15 Watt, Elecraft K2 (which in comparison to Gil's 100 mW, is a fire breather)....... I don't regret that decision one bit. I leave the power knob turned way counterclockwise at around 5 watts and still very easily make armchair copy contact with Wes most every night. CW is like a free, built in amplifier.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

KK0G

gil

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Re: QRPp // HF Morse at LESS Than One Watt
« Reply #2 on: September 17, 2014, 04:30:48 PM »
Hi Guys,

Same story when Ray and I talked while I used my Buddistick on 30m inside the house, with 2W. How much of that was radiated? Not much... The most power I can muster here is 12W with my KX3, then 5W with K1 and MTR, and finally 1.5W with my Rock-Mite 40. Now, how much longer can I transmit using my MTR compared to a 100W radio? Is it better to transmit a SOS on a 100W radio for an hour or at 1W for days? With grid power, no problem. Being forced to operate on batteries brings a whole new set of challenges. People will say "I can turn my power down..." Yes, but receive current draw is still going to be high. That is why a small QRP CW rig is so valuable. I think the ideal power is 3 to 5 Watts.

Some detractors say that it's the receiving station that does all the work... Not quite true. Sure, sometimes my signal is received in Europe by big beam antennas, but not always. QRP-to-QRP contacts are no problem either. As Ray points out, it's a matter of signal-to-noise ratio. Even if the receiving station does the "work," we're not talking about chopping wood here (radio is NOT a sport!)... Who cares... Contact is established, period. Actually, I've had very good results with end-feds, the best thing since sliced bread!

The only reason I keep my KX3 is because it is my only multi-mode radio that can also be used to send email through Winlink. Otherwise, I would have sold it. It's a great radio, probably the best QRP radio out there, but expensive. I would have been content with my MTR and K1 (ol' drifty), even with 20 and 40m only. I very rarely hear ragchews on 30m, it's all 599-73 contacts, not for me. If I was to build a Tri-Bander, I would choose 15,20,40m. Only problem then is contest week-ends...

I would certainly encourage everyone to turn the power knob down, just to see how low you can still be readable. In CW, that's VERY low! Voice modes, not so much. Don't know Morse code? Try PSK31. I like that mode, though I don't really need or use it. Good for low-power digital.

Another great feature of some small QRP CW radios is the message memory function. You key-in your Morse code message in recording mode, set the interval, say one minute, and turn it on. Your message will be transmitted every minute until you turn it off. Kind of useful when calling for help while you keep your finger on that sputtering artery :o

Sure, low power CW and Morse code are archaic, but they sure as hell work!

Gil.

RadioRay

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Re: QRPp // HF Morse at LESS Than One Watt
« Reply #3 on: September 22, 2014, 12:07:42 PM »
KK0G, you are quite correct in questioning all this 'QRP' nonsense!

As you know, and the EXPERTS AGREE; QRP does not work: in fact - it CAN'T!  You see, only hideously expensive radio transceivers with huge amplifiers and a couple of tons of tower have a CHANCE of ever reaching another ham radio operator.  Besides, 'Morse code is dead - nobody uses it anymore' that's a statement as sound as the U.S. dollar!  It's scientifically impossible for small, inexpensive, home built , low power equipment to work.   ::) Satire  ::)

To paraphrase Kopernicus:  'And yet, QRP works.'





« Last Edit: September 23, 2014, 11:35:33 PM by RadioRay »
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

Lamewolf

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Re: QRPp // HF Morse at LESS Than One Watt
« Reply #4 on: October 04, 2014, 09:07:51 AM »
KK0G, you are quite correct in questioning all this 'QRP' nonsense!

As you know, and the EXPERTS AGREE; QRP does not work: in fact - it CAN'T!  You see, only hideously expensive radio transceivers with huge amplifiers and a couple of tons of tower have a CHANCE of ever reaching another ham radio operator.  Besides, 'Morse code is dead - nobody uses it anymore' that's a statement as sound as the U.S. dollar!  It's scientifically impossible for small, inexpensive, home built , low power equipment to work.   ::) Satire  ::)

To paraphrase Kopernicus:  'And yet, QRP works.'

Yeah, and non resonant antennas don't work either ! ;D

Sparks

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Re: QRPp // HF Morse at LESS Than One Watt
« Reply #5 on: June 02, 2018, 12:09:24 AM »
To paraphrase Kopernicus:  'And yet, QRP works.'

I did study the history of astronomy, for a long period. Kopernicus was my great hero then and now. However, that famous quote is attributed to another great astronomer, a century or so later:

https://en.wikipedia.org/wiki/Galileo_affair
https://en.wikipedia.org/wiki/And_yet_it_moves