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LF: Radiated power

To: [email protected]
Subject: LF: Radiated power
From: "Walter Blanchard" <[email protected]>
Date: Tue, 22 Jan 2002 10:07:40 +0000
Reply-to: [email protected]
Sender: <[email protected]>
An interesting number:

If Jim's measurement of MM0ALM's field strength is right, at 50 uV/m, and assuming the distance between them is 600 kms mainly over a standard medium-conductivity land path then :

According to the CCIR standard propagation curves (Vol 5, "Propagation in non-ionised media", Recommendation 368-4) a radiated power of 1 kW at 136 kHz from a short vertically-polarised monopole would produce a field strength at Jim's distance of 500 uV/m.

Jim measured 50 uV/m so MM0ALM's radiated power must be 10 dB below 1 kW - 100 watts. Jim's measurements I have found to be pretty accurate in the past but if anyone else can make accurate field strength measurements perhaps they would do so next time MM0ALM comes on.

I've made my own measurements and they agree with Jim's. I've also measured field strengths of a number of "local" stations and knowing exactly what they're using for transmitters and antenna systems the results tie up pretty closely (including, by the way, confirming G3AQC's statements about his power). NONE of the locals I measured were exceeding 1w radiated.

What people choose to radiate is up to them and the RA but let's not have any boasting about DX worked when they've been using illegal powers. They should note that, as per above, and unlike HF, it is not that difficult to estimate pretty closely what they're radiating - one advantage of basing the licence on radiated and not "DC input" power. Of course, if MM0ALM holds a "high-power" NOV then good luck to him but he should declare it.

Might also be worth noting that any DX records made while using illegal powers are invalid and will not be recorded.

Perhaps anyone who thinks he's being slandered would publish full details of his transmitter, antenna and earth system and let others make their own judgements. Far better than just hurling insults around.

Walter G3JKV.


                





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