Hi Mal and Uwe: I think NAVSTAR is more likely to be a NAVTEX antenna than a GPS antenna. It might just be designed for 518kHz and therefore not so suitable for LF, but some of these ships antennas w
From Peter G3PLX: Greetings to the group. I was subscribed here some years ago when we first got 136kHz and I was transmitting on the band myself but I have been busy with other projects since. One o
Mike; As Steve says, you will need a huge choke in the braid to have much effect. What you are trying to do is form a potential divider, with your choke at the top and 'the impedance-to-ground of the
From G3PLX: Some results from the QRPP tests for which I asked for volunteers a few days ago. The test were to evaluate the performance of the 'Clicklock' technique which I have been developing. This
From G3PLX: I have some black coloured poles (from www.sotabeams.co.uk) but they were certainly not carbon fibre, but glass fibre. Maybe the black paint was conducting, I don't know. I wanted them as
From G3PLX: If there's anyone within about 500km from me at 54N 3W (i.e. daytime surface wave range) who could transmit a few micro-watts of very stable (preferably GPS-derived) carrier on 136kHz, I
Jim, Markus, and the group: First of all, many thanks Jim for doing those measurements. I don't have the test equipment to do these things and I am too far away from Rugby. Your results seem to say t
Alan: Yes, it's true that if the signal is wider than your receiver and is coherent (like a pulse), then the SNR will increase if you widen the bandwidth, inspite of the fact that the noise increases
From G3PLX: Some small corrections to the calculation of the erp of a LORAN line... The mean power of a LORAN transmitter is a little lower than I said. If the published peak power is P and the Group
From G3PLX: I calculated the radiated power of a LORAN line now, but I would like other people to check if I did it right, because the result is surprisingly small. The spectrum measurement made at R
Marco: Thanks for the info about the LORAN transmitter. That's very useful, and it's surprising how low is the mean power. If it's 7.5kW at 180 pulses/sec., then for example the Lessay chain transmit
Alan: Yes I have spent some time at the Megapulse site, and that tells me all the power levels, but I assume these are given as the peak pulse power. What I need now is to convert these to mean power
Wolf: That would be another way to get a calibration, so long as we also knew the emrp of DCF39. If you are close enough to receive surface wave from DCF39 and surface wave from Sylt, then a ratio of
From Peter G3PLX: Does anyone have any information about the actual level of spurious emission from the LORAN transmitters in the 136kHz band? The only specification I know of says something like the
From G3PLX: Ferrite cores in TV line output and switchmode power supplies often have an air gap. This means that the effective permeability is not very high. This is done because the transformers in
Wolf: The item about Coherent Reception in RadCom was copied from an email by me to Dave. If someone can tell me what is the attachment size limit on this reflector, I will see if I can post it here.
From Peter G3PLX: Anyone reading G3YXM's column in RadCom April who is puzzling over the coherent phase and amplitude plot in there from me, please note that the 'Level' and 'Phase' legends have beco
John: By all means quote my explanation, but it's not an explanation which should be attributed to me, since the reason behind it has been known since LORAN began. It only applies to LORAN transmitte
Andy: OK, let's give it a try at -23dBm (5uW) over the 400km path between us. I can handle any decimal part of a Hz now, not just proper fractions of a Hz, so long as I can leave the system running c
