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Joined: Sat, Apr 4th 1998, 00:00 Roles: N/A Moderates: N/A

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Latest Posts

Topic Author Posted On
FT8 WD5IQR on 29/8/17
FT8 is now handled as a mode by LoTW in latest versions of TQSL. See https://lotw.arrl.org/lotwuser/default (LoTW login required)
HF use of squelch wheelgunnut on 22/8/17
Bill -

Squelch is more useful with FM than with AM/SSB because FM signal quality falls to pieces very rapidly when it weakens toward the noise level. (Threshold effect) AM/SSB signals, on the other hand (particularly SSB), degrade more smoothly as they get weaker. You can still copy signals that are near the noise level. With effort!

Also, HF propagation is often more variable than VHF+. You might want to copy a signal that varies between S3 and S9 over a few seconds. Squelch might cut out the dips when you could still copy them.

You can reduce the "noise blast" after a transmission stops by adjusting your AGC or RF gain controls carefully.

It comes down to personal preference, but most ops seem to prefer to keep their "ears" open as much as possible on HF/MF.

73 Martin AA6E
FT8 AG5P on 13/8/17
**ADDED** Latest update of TQSL and LoTW support FT8 without any fuss. Disregard following.


Easy workaround:

Run TQSL
Select File > Display or Modify Prefences...
Select ADIF Modes tab
Add... ADIF Mode = FT8
Resulting TQSL mode: DATA
OK
OK
Exit TQSL

Now, when you run TQSL, ADIF file's FT8 QSOs will be mapped into DATA QSOs for LoTW. ARRL awards category DATA is the same as JT65 and other digital modes. It would be nice to record your Q's as FT8 in LoTW, but it's not necessary.

73 GL Martin AA6E
Electric Field Strength Limit Calculation kj4saf on 31/7/17
Which FCC rules are you referring to?

The basic rule has to do with PEP output power level with no reference to field strength or antenna gain.

If you are referring to the RF exposure (safety) rules, the considerations are different, and rather more complicated. I recommend you consult http://www.arrl.org/rf-exposure, if you haven't already done so.

Your calculation seems to be on the right track -- You are looking at the field strength in the far field of an isotropic radiator. But we are rarely in the far field (certainly not for common frequencies at 3 meters separation), and our radiators are never isotropic!

Actual electric field strength depends on many things - distance from radiator, antenna radiation pattern and gain (including transmission lines), polarization, as well as power level and environmental details. It's hard to make an accurate calculation from first principles. Mostly, amateurs are well advised (IMO) to use the broad "safe harbor" rules that say that for a certain frequency, separation distance, and power level you are OK without doing a precise measurement. (And the level is different if you're talking about yourself or your family vs the general public.) If you come close to the "danger" level, then you are supposed to do a real measurement to show that you're OK -- or else reduce power.

73 Martin AA6E
FLDIGI power problem KC8WPW on 31/7/17
You probably want to set your (peak) power level to 100W -- but then turn your mic gain (audio level) down, so that the average power level is 20-30 W. But this depends on what radio you're using. Some radios don't have a mic gain control, and that will be a problem.

If your average power on PSK31 (I assume you're talking about this mode?) is 30 W (or so), your PEAK power will be close to 100W. That's because PSK31 and some other modes transmits multiple simultaneous tones. If your average power is higher than about 30 W, you will be clipping the peaks -- making an unholy mess on the band! (Sadly, this happens all too often.) Your ALC light, if you have one, should never light, and your speech processor (if you have one) should be off. Linearity is your friend!

On the other hand, if you're talking about RTTY or JT65, your peak power is equal to your average power, because these modes only transmit one tone at a time. Linearity is not an issue.

In future, it would help if you tell us what make/model radio you are using.

73/GL Martin AA6E

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