QRP in a Contest +Do Contesters tell a fib?-video

[The Slab Bacon]

Obscene power.

even IRB ran 100 watts

"Now, that's quite a message............."      

[WD8BIL]

Even with a precision laboratory instrument for measuring field strength, the absolute reading is meaningless unless you have some kind of reference point to use as a standard for comparison.

Not really, Don. From the antenna feedpoint back to the receiver, including cables, wattmeter, amp or any other insertion, the absolute reading can be made with reasonable confidence. I do it all day here at work.

Your inclusion of the antenna uncertainties is right on the money. As with any measurement device in a lab enviroment, there always is a level of tolerance. But after one gets to know the ropes that uncertainty can be minimized significantly. My antennas here in the lab have known correction factors gathered from the actual STABLE enviroment they are being used in. If I see a signal measuring 30dbuv I can be comfortably sure it's accurate. This has been corrolated by measurements from our 3rd party verification lab in Tenn. We rarely vary by +/-3db.
The problem with outdoor real world antennas is as you mentioned plus, we can never be certain about the signal path, reflections, angle of arrival .... ect

That being said, if you can determine the loss in your antenna you can come close enuf to give a report of 20 over S9 (50mv) +/- 3 db or so.

[k4kyv]

After months or years of experience at a given QTH and with various antennas, you can develop a sense of how well a signal you hear is coming in, and meaningfulness in the signal reports you give out. Problem is, the bloke at the other end doesn't have that sense, and he hears the same report in the S9+10 that you give out, as in any one of the other S9+10s that he hears. But if you compare his s-meter reading with the background noise when he drops his carrier or stops talking on slopbucket, he at least has some idea of how well his signal is really coming through the background noise and QRM.

Probably the best indicator of absolute signal strength to the antenna terminals of the receiver would be something like a "dB over a microvolt" scale, since just as in the case of audio, the range of signal strengths is too great for a simple linear-reading meter calibrated directly in microvolts, and a logarithmic scale is needed.

Without a meter, five levels of S-units would be sufficient, and can be estimated reasonably well by ear: (1) barely perceptible, (2) weak but clearly audible, (3) fair, (4) strong, (5) Extremely strong, aka "strapping".  You could take the existing 9-step scale, eliminate every other number, and simply call those 5 steps described above S1, S3, S5, S7 and S9 and no-one would ever suspect the difference.  After all, who's going to argue over whether the signal is S7 or S8, or notice that you never give out reports of S2, S4, S6 or S8? But on phone, I usually just verbally describe what I hear, without s-numbers at all.

Right now, my s-meter is inoperative; I have a long-standing, pesky, persistent flaky problem in the 75A-4. The meter won't stay zeroed; one time it is trying to peg backwards, another time it drops only down to mid-scale even with no antenna connected. Replacing tubes hasn't helped. Every time I think I have fixed the problem, it re-occurs after a few days or weeks. Like 99% of my  radio malfunctions, it is intermittent, and I haven't taken the time to monitor all the associated voltages, currents and resistances in the agc-controlled stages and meter bridge circuit to chase it down, since that would likely involve running the receiver on its side with the bottom cover removed for an extended period of time to catch the culprit in action.

[WD8BIL]

Without a meter, five levels of S-units would be sufficient, and can be estimated reasonably well by ear:

Ahhh yes. The historical self calibrating GUESS METER!

I got one of those on my Scott RCH Receiver. Don't dispute it. You'll be wrong!

[W5COA]

I get a chuckle out of receiving a "booming signal" report, but afer two or three exchanges, the other station still hasn't figured out my name, or what equipment I am running.

This tells me that my signal is probably even with the noise level, or that the guy is as hard of hearing as I am. 

Regards,

Jim

[K5UJ]

Jim, don't be too hard on him.  I do things like that too.  I work a guy who is new to me and he tells me his name and I call him something else because lately half my mind is on monitoring the gear to make sure changes I have made are okay.

Don,  maybe the meter shunt is flakey.  If it is like the A-3 it is 1/2 w. 220 ohm.  maybe the prob's in the meter itself.  I have no idea how hard it is to get a replacement but it looks like a common meter.

[k4kyv]

It doesn't show any of the symptoms of a bad meter or bad shunt. I don't think that could cause the meter to flake between a negative reading and a mid-scale positive reading with no signal and the rf  gain fully open. I can re-zero it with the meter zero pot, and within a day or so it either won't go below mid scale with no signal, or else it tries to peg backwards.  If I cut power to the receiver, it drops back to zero. Turning back the  rf gain causes the normal effect of the meter to deflect to the right without a signal. There seems to be something out of balance in the bridge circuit.  But since it  changes from day to day, or even hour to hour, I haven't been able to narrow down what is acting up. Too many components working together simultaneously to figure out what is wrong without checking each component at a time.  Not sure a working s-meter is worth the trouble.  The receiver otherwise receives normally. I may just disconnect the meter so  that I am not constantly distracted by the silly thing, till I have time to put the receiver on the bench and seriously chase the problem.

To top it off, Collins revised the s-meter circuit sometime along the way, and apparently the actual circuit doesn't correspond to the schematic in the manual, even though I think I have the original manual that came with the receiver.  I have a schematic of the other circuit round here somewhere, but "round here somewhere" doesn't cut it when you need it right now.

[KX5JT]

I tell someone they are "Above the noise and full-quieting, beautiful signal"... or "I have a good copy on you, you're riding just above my noise floor but I have no problems with the copy."  or "Sorry OM you're right in my noise and it's difficult pulling you out... maybe we can try again another time." 

I'm starting to realize S-meter readings do not mean much except like Tom says, in the context of a lot of different signals on the frequency at the same time for comparisons.  My ricebox easily comes over S9 on a decent signal but rarely goes of +30 unless it's Don KYV or Brandon IIA ... but my NC-300 will hit the 60 over mark on these guys usually. 

QSL? QSL.

[W1RKW]

Obscene power.

even IRB ran 100 watts

"Now, that's quite a message............."      

Irb had some good phrases and expressions.  Got to keep them alive!

[The Slab Bacon]

Obscene power.

even IRB ran 100 watts

"Now, that's quite a message............."      

Irb had some good phrases and expressions.  Got to keep them alive!

Like him or dislike him, Irbisms will be around for a long time to come.

"Just listening for that little voice in the wilderness"..............................

[The Slab Bacon]

Or these...........................

[KB2WIG]

The following is my all time irb favoright.


http://amfone.net/Amforum/index.php?action=dlattach;topic=28951.0;attach=28570

 I just wish someone had rolled tape on the famous " payfone QSO from jail"

Thoes wer the days


klc

[The Slab Bacon]

The following is my all time irb favoright.
http://amfone.net/Amforum/index.php?action=dlattach;topic=28951.0;attach=28570
 I just wish someone had rolled tape on the famous " payfone QSO from jail"
Thoes wer the days
klc

Nah........... My favorite one of all time is the Prime Minsta screaming at Irb to "shut
the f@#% up." I roll on the floor every time I hear it! !  I would have posted it with the others, but this bbs software wont accept a .ram file.

[K5UJ]

  But since it  changes from day to day, or even hour to hour, I haven't been able to narrow down what is acting up. Too many components working together simultaneously to figure out what is wrong without checking each component at a time. 

I guess if it were me, my next step would be to try two things, go in with rubber coated tongs and give a few tubes a wiggle, and shoot some freeze spray on some of the resistors and solder terminals around the meter (but avoid the tubes  ). and see if the meter says "ouch" on any of the joints or resistors.

[K1JJ]

I guess if it were me, my next step would be to try two things, go in with rubber coated tongs and give a few tubes a wiggle, and shoot some freeze spray on some of the resistors and solder terminals around the meter (but avoid the tubes   ). and see if the meter says "ouch" on any of the joints or resistors.

Yep, good advice, Rob.

I know of *several technicians who alternately use a heat lamp and then freeze spray on suspected areas. (with the rig on and a signal/ tone injected to listen to)  It's amazing how this will cause intermittent connections and faultly components to show themselves.  Then use a plasdick handle to tap everything.

Heat, cold and vibration is an effective combination for troubleshooting.

* BTW, I am one of those techs...

T

[K5UJ]

Thanks Tom but if there is any success in my advice it is only because it is not my problem.   If it were my A-4 and my meter problem I'd be sitting looking at it with no clue about what to do.