Quiet Enough for QRP?

[Todd, KA1KAQ]

QRP is a good way to get your antenna system in shape.

QRP is a good way to develop an aspirin dependency and a serious *twitch*. An antenna party with your pals and a MFJ analyzer strikes me as a more efficient and less annoying way, provided you supply the beer. They say a mind is a terribly thing to waste, well I think a signal is a terrible thing to lack. As someone who was pissweak at 100watts for too long, life is indeed too short.

Need to get Mr Photoshop to make me up a fake pulp fiction cover that says

                        I Was A Hundred Watt Pissweaker!

complete with a caricature of a young JN sitting in front of a 32V or DX-100 tuned to 3885, beads of sweat rolling down his face, eyes bulging out as a voice comes out of the speaker saying "Boy - ya bother me. I can't hear ya cuz yer PISSWEAK!"

Maybe a DX version too, tuned to the DX window with the voice coming from the speaker saying "Negateeve....Negateeve.....QRMary.....QRNancy......No Copy.....No Copy......"

[k4kyv]

Maybe a DX version too, tuned to the DX window with the voice coming from the speaker saying "Negateeve....Negateeve.....QRMary.....QRNancy......No Copy.....No Copy......"

But nevertheless, the signal report is still "five-nine".

[K5UJ]

One secret to successful low power (not technically QRP but 20 watts say) operation is in my opinion, having a lot of audio.  You need a rig that will handle up to 150% positive and a lot of compression.   Of course in pure power terms, that makes a 20 watt rig a 120 watt pep rig, not exactly "low power."   In summer in the day time on 75 I have operated my slopbucket transceiver in this way because it was too hot to drive the amp with it, and been surprised at who I could work and the better than expected sig. reports.   The only problem has been severe daytime QSB causing my sig. to nosedive into the noise, which would not have happened if I had been running 100 w. or more. 

For this reason when I looked at the Small Wonder Labs 2.5 w. AM kit and saw that it limits modulation to 80% I quickly lost interest.  If you feed typical unprocessed audio into that rig your average modulation level will probably be around 20 or 30%.  I do not see any reason to limit peak modulation to such a low figure with solid state components unless there was a design assumption that users would not have asymmetric peak limiting.  Even so, why limit peak positive and negative to 80% unless the RF can't support more than that.   This reminds me of the Kenwood TS870 in which on AM, the firmware DSP design similarly limited peak modulation, making the box an undesirable rig for AM. 

I've worked guys running DX100s who sounded like they were on broadcast rigs.   To paraphrase something Derb once posted, the antenna is truly what makes you a strapper.   

73

rob

[W3FJJ]

For this reason when I looked at the Small Wonder Labs 2.5 w. AM kit and saw that it limits modulation to 80% I quickly lost interest. 

Rob, it's real easy to open,the closed loop audio, that restricts positive peaks, on the retro- 75 ,just snip one end of diode, and modulation is
easily near 100 percent
positive. It looks about as good as any of my homebrew rigs, or commercial plate mod rigs... And alot better than my FT-920 ricebox   

[Todd, KA1KAQ]

Chuck, I don't recall now what you were running 25w with the afternoon I worked you, Slab, and Jay down on the Fudd net, but I could barely make you out at first. The next time you were S-9 and the last time you started out at 20 over, then slowly faded back down. Of course by then it was time to give the frequency to the SSB group, so who knows how well you might've come in afterward? I know you had a strapping signal for a while, at least.

[W3FJJ]

Todd, I was on the ft-920.  Well just two days ago I got my 80 meter diaper pole
back up to 70 feet (from 35 feet) You should here me alot better now. And of course
if i fire up the QRO rig...

[K5UJ]

Rob, it's real easy to open,the closed loop audio, that restricts positive peaks, on the retro- 75 ,just snip one end of diode, and modulation is
easily near 100 percent
positive. It looks about as good as any of my homebrew rigs, or commercial plate mod rigs... And alot better than my FT-920 ricebox   

Tnx 4 info--good to know there's a mod for the rig; that extra 20% can make a big difference Chuck, esp. with 2.5 w.

73

R.

[k4kyv]

For this reason when I looked at the Small Wonder Labs 2.5 w. AM kit and saw that it limits modulation to 80% I quickly lost interest. 

Rob, it's real easy to open,the closed loop audio, that restricts positive peaks, on the retro- 75 ,just snip one end of diode, and modulation is
easily near 100 percent
positive. It looks about as good as any of my homebrew rigs, or commercial plate mod rigs... And alot better than my FT-920 ricebox   

Then why in hell did they limit the positive peaks to 80% in the first place?

[W3FJJ]

Then why in hell did they limit the positive peaks to 80% in the first place?

The rig doesn't have a mic gain or modulation meter, I think the idea was to prevent it
from over modulation. It has automatic gain circuit, that no mater how loud you shout into
mic,  it won't over modulate
negative, unfortunately it also restricts the positive as well..

[W9GT]

Interesting that this simple comment about how good conditions were becomes a rant against QRP!   I think we all get it that it is good to run QRO when you can, especially under challenging conditions with high noise and/or QRM.  Using the AM mode is a challenge sometimes....try doing it on VHF!

I also built one of those little Retro 75 QRP AM transceivers and I have had a ball with it.  It was a challenge and a fun thing to experiment with while trying to make contacts under adverse conditions.  By my use of this little rig, I am in no way trying to make a statement or railing against QRO. 

I love QRO rigs and I'm building a new one right now.  That, however, doesn't preclude enjoying and experimenting with other things, including QRP.

73,  Jack, W9GT

[Steve - WB3HUZ]

As opposed to a rant for QRP.   

[Todd, KA1KAQ]

I don't see any of it as a rant so much as aversion to what many of us have experienced far too many times: the pissweaker no one can hear who goes on endlessly. QRP is exactly like QRO in the sense that there's a time and place for it. I've got nothing against anyone enjoying their favorite aspect or mode of amateur radio, provided they don't assume others feel the same way and inflict it on the ongoing QSO of others.

Few, if any, of us have limitless time to enjoy radio, so it makes perfect sense we'd prefer to use that time as we see fit. QRP, QRO, CW, corntesting, etc. Many of us chafe at the thought of corntesting too, even though some enjoy it. For the same reasons, it tends to get inflicted on us and isn't how we'd choose to spend our radio time.

Otherwise it's all good. 

[K5UJ]

Jack,  that's really cool that you got one of those rigs.  I'd really like to hear it sometime.  Maybe I'll catch you on 75 some weekend.  You have a pretty good antenna so it should work.  This power level puts antennas to the test on both tx and at my end, rx.  BTW I sent you an email about racks but I'm not sure you got it.   We might have some where I work in a few weeks.

Rob 

[Ed/KB1HYS]

Try giving out honest signal reports, Maybe people would get the hint.

A 59 all the time is no help, and a 47 (or even a 33) shouldn't be taken as an insult, as so much is dependant on the band conditions etc. BUT it should be taken as a hint that the other station is working hard to hear you... maybe you should sign and look for a better QSO elsewhere out of courtesy?

Readability - Strength - Tone:   RST Signal Reports
R-S-T
Characteristics Readability
R Strength                                             S strength           T (cw N/A)

1- Unreadable                                       Faint/barely perceptible
2- Barely readable                                 Very Weak Signal
3- readble with difficulty                         Weak Signal
4 - Readable with almost no difficulty        Fair Signal
5- Perfectly readable                              Fairly good Signal
6-        N/A                                          Good Signal
7-        N/A                                          Moderately Strong signal
8-        N/A                                          Strong signal
9-        N/A                                          Extremely Strong signal

[K1JJ]

"  4 - Readable with almost no difficulty       BY        5 - Fairly good Signal "


Give someone a 4X5 and they will usually be disappointed enough to look outside to see if the antenna is still up.
But it really means being heard with almost no difficulty and having a fairly good signal.  Interesting.

What has really taken the place of these old  R X S  signals is the "XX over 9" scale.  

Signal reports today mean you must be at least S9+10 or be considered weak. A S9+40 is considered loud.   Imagine adding 40db to the old 5X9 report that already meant "Perfectly readable with extremely strong signal" ...

[W1RKW]

For this reason when I looked at the Small Wonder Labs 2.5 w. AM kit and saw that it limits modulation to 80% I quickly lost interest.  

Rob, it's real easy to open,the closed loop audio, that restricts positive peaks, on the retro- 75 ,just snip one end of diode, and modulation is
easily near 100 percent
positive. It looks about as good as any of my homebrew rigs, or commercial plate mod rigs... And alot better than my FT-920 ricebox  

Then why in hell did they limit the positive peaks to 80% in the first place?

As one who built a Retro75, yanking the LED opens the loop but that comes with a drawback.  As modulation approaches 95% it starts producing some nasty distortion products.  The final transistor could probably use a source resistor or some other biasing technique to clean it up and provide better modulation.  Audio wise this little rig isn't too bad and it's certainly not space shuttle or SSB quality.

[Steve - WB3HUZ]

There is a nice review of the Retro 75 in the October QST.

[kb3ouk]

If i remember right(don't hold me to it because i don't have the article here to look at to see if i am right) the review in qst said 80% modulation as maxium because that was the highest you could go and still have a clean signal.

[k4kyv]

R Strength                                             S strength           T (cw N/A)

1- Unreadable                                       Faint/barely perceptible
2- Barely readable                                 Very Weak Signal
3- readble with difficulty                         Weak Signal
4 - Readable with almost no difficulty        Fair Signal
5- Perfectly readable                              Fairly good Signal
6-        N/A                                          Good Signal
7-        N/A                                          Moderately Strong signal
8-        N/A                                          Strong signal
9-        N/A                                          Extremely Strong signal

It would make more sense to use the 1-5 scale for strength, too.  Take out every other one of the above, and this is what you have left:


1- Faint/barely perceptible
                            
2- Weak Signal

3- Fairly good Signal
                                          
4- Moderately Strong signal
    
5- Extremely Strong signal

Doesn't that cover the full range, as readily perceivable by ear? Attempts at resolution down to a distinction between "faint/barely perceptible" and "very weak", or "good" and "moderately strong" become so subjective as to be meaningless.

James Millen got it right the first time.  My 1935 HRO's S meter is calibrated from S1 to S5. S5 is at mid scale and the top half of the scale is blank.

[Steve - WB3HUZ]

Yes, the 1-9 scale is too granular.

A level 6 could be added to Whirl Wide!


Shelby, the article claimed that the 3rd-order IMD was lowest a 80 percent modulation. Since the kit does not modulate any higher, we don't know what happens at 90 or 100 percent.