Hi Mauro, with this dimensions the antenna impedance will be mainly determined by the loss resistance. For a loop circumference of 20m and a 2 turn loop the copper resistance will be about 0.13 Ohm.
Hi Stefan, regarding: Now my question: Is it better to remove a BF981 amp stage (about 16 dB to 18 dB gain!) in front of the mixer (SBL-3) to get a lower RX noise or do i better reduce the gain on th
Hello Wolf, well said. From the IARU R1 VHF managers handbook: A valid contact is one where both operators have copied both callsigns, the report and an unambiguous confirmation. However no recourse
Hi Andy, OK about the known callsigns. My focus was on the second part: "However no recourse should be made during the contact to obtain the required information, change of frequency, antenna directi
Hi Bob, small is a relative thing on LF. A DDRR with a perimeter of 0.25 lambda and a height of 0.025 lamdba is indeed small on 144MHz, but on 137kHz the perimeter becomes 550m and the height a respe
Hi Tom, Bob, I had a look in my Rothammel Antennenbuch (geniune "Militärverlag der Deutschen Demokratischen Republik" version, 1974) and indeed it states 0.007 lambda height. But what about ground lo
Hi Stefan, getting a cardioid antenna using a magnetic ferrite rod (or loop) antenna and an small electrical antenna is very simple and done for ages in 80m ARDF (foxhunt) receivers. Sure it can be d
Hello Andy, Chris, the circuit diagram can be found in this PDF: http://icas.to/idc-136ii/idc-136ii-kit-manual-eng.pdf In contradiction to the block diagram at http://icas.to/lineup/idc-136ii-kit-eng
Maybe also worth to mention: Capacitive coupling of the driver to the gate will reduce the peak voltage at the gate by half (assuming 50% duty cycle). The IC driver voltage should be at least 12V in
Andy, oops, you're right. I didn't read far enough down the mail to see that you also recommended diode restoration. I have to read more careful before replying ... 73, Rik ON7YD Van: owner-rsgb_lf_g
HI Clemens, but on LF Rrad <<< Rloss, in that case it is very close to 6dB. And often adding a topload wire will decrease Rloss (footprint theory), so the actue gain will often be more than 6dB. 73,
Not sure that QRS will work with all USB to serial adapters, but I have tried several without problems. Currently I am using the popular CHIPI-X10. Available from Digikey, Mouser, Farnell etc.. at ab
Hello Chris, Frequency: inter-Europe QRSS (good to start with) is centered around 137.7kHz USB or CW: depend how you generate the signal. CW if you key the TX, USB if you use an audio tone. The resul
Hello Luis, is 472kHz included in CEPT T/R61-01 in Spain? In Belgium it is. So anyone with a CEPT-HAREC approved license can operate 472-479kHz and 501-504kHz with 5 W EIRP using ON/xxx (for a period
Hi Chris, I wouldn' worry about that. Assuming that you aim at 50 Ohm the SWR will be 1.1/1. This will cause a reflected power of 0.2% (or otherwise: a decrease of 0.01dB of the radiated power). 73,
and if I remember well PA0A has been copied at the US west coast some years ago, must also be in the 9000km range. 73, Rik ON7YD Van: [email protected] [owner-rsgb_lf_group@blackshee
Being on holiday in I seemed to have missed some nice propagation on 472kHz. Just a thought (or 2): - With dropping solar activity it is likely that propagation will improve the coming years. - The d
Hello Stefan, Mike, I assume that a good working dipole at very low height (4m = 0.6% of lambda) is due to a poor soil. I remember to have read somewhere thate (French?) military in the Sahara desert
Hello Luis, the radiation resistance of your antenne is probably not the calculated 8 Ohm, due to the fact that the 80m "tower" is not perfect and will introduce some loss. Or another way to look at
