Dear LF Group, Some comments on G3JKV's recent E-mail - I calculated the ERP on the basis of the measured antenna current and estimated radiation resistance of the two antennas. Part of the reasoning
Dear LF Group, ZL2CA wrote: But the intended thrust of this email is to ask about if anyone can find a reference to a BESSEL BANDPASS filter. Text books all say that the Bessel low pass filter has th
Quote: "The intensity E (known as the field strength) of a transmission at a distance D from a source transmitting P watts of RF power via a half-wave dipole in a free, unobstructed space, can be est
Dear LF group, Looking through my box of crystals recently, I found some operating in the range 30 - 40kHz. They are in glass envelopes, and I noticed that the metalisation on each side of the quartz
Dear LF Group, I believe most LF amateurs favour string for their antennas - preferably well soaked in brine to maximise conductivity... But seriously, I have found 24/0.2 or 32/0.2 stranded PVC insu
Dear LF group, Congratulations to Jack and Peter on last night's reception of VE1ZZ's signals. Funnily enough, I was using DL4YHF's excellent Spectrum Lab software to record spectrograms of 136.5kHz
Dear LF group, Seems that quite a few people are interested in the Decca "guard" circuit The original circuit diagrams are hierarchical and take up several pages, and most of the detail is not much u
Dear Andy, LF group, To a reasonable approximation, the voltages in the tank circuit, and the guard circuit, will vary in direct proportion to the supply volts for a given value of load impedance. Th
<?color><?param0100,0100,0100>Dear Andy, LF Group,<br><br>Aha... wondered why you hadn't mentioned it before - unfortunately, the guard circuit is not shown in the simplified diagram in the LF handbo
Dear Richard, Andy, LF Group, I once had a similar problem where one FET blew up in an amplifier, and it's replacement immediately failed too. This turned out to be because the other FET, although no
Dear John and LF group, I was interested in G4CNN's experiments with loop antennas - in response to some of the issues he raises here is another long E- mail - please delete now if the subject bores
Dear LF Group, Nice to see a new face on 73kHz - I was very pleased to work G3AQC for his first 2-way QSO on 73kHz. It was a bit "asymetrical", I gave Laurie a 589 report, but had to resort to QRSS t
Dear Andy, LF Group, To generate linear phase shift, how about a PWM: Generate a sawtooth at carrier frequency, feed into one input of a comparator. Other comparator input is analogue "phase" signal.
Dear Laurie & Group, Not sure if a band plan exists as such, but the way it has normally been worked in the past is something like: 71.6kHz - 71.75kHz manual CW "window" (when the Rugby TX is running
Dear LF group, I have been trying the 'Eclipse' data logging software in preparation for group CFH monitoring experiments - it seems to be working fine, although I can't get all parts of the eclipse
Dear LF Group, Heard 589 QRSS signals from G3AQC on about 71.7kHz last night and this morning - Laurie is now one of the best signals on the band. I tried calling you on 73k, Laurie, but think you mu
Dear Martin and LF Group, The CFA antenna has been doing the rounds for a while - the problem is, like most "miracle" antennas, it does not seem to live up to it's claims in real life. Nobody, includ
Dear LF Group, Thanks to DF6NM and ON4ZK for the cross-band QRSS contacts last night; also thanks to DK5PT and G3OLB for the reception reports. I did not hear any other stations on 73kHz last night.
Dear LF Group, I think this is the main function of the "transient soak" chokes in the Decca design - diverting the current into the fast diodes rather than through the Mosfet diodes during the switc
Dear LF Group, I intend to be QRV on 73kHz this evening from about 2000utc. I will use 71.65kHz, unless other stations want to use it for manual CW. In that case, I will use my "normal" QRSS frequenc
