Hi Stefan, based on 470nF and 137kHz the inductance is only 0.47uH (what means XL = 0.4 Ohm). As Q = XL/R for a Q = 8 the loss resistance is 0.05 Ohm. This seems acceptable to me. Due to the very low
Jim, Alan, Scott, Daniele, Thanks for your comments and suggestions! I will build the preamp and try to get a higher Q. I have some WIMA FKP-1 caps, 2 kV type in that C range and will buy a bigger co
Hi Stefan a few points from a quick read your message ......... 1st The null depth......I think there could be two reasons why it isnt deeper. One is that the vertical dimenion of the loop could act
Hello Clemens, I measured the Q by coupling to a smaller loop that was connected to my DDS VFO. First i found the resonance frequency, then i in- and decreased the frequency until û was 0.707x u max,
Dear Stefan, LF Group, I did some experiments on single-turn loop Q when designing the "bandpass loops" (BPloops2.pdf at https://sites.google.com/site/uk500khz/members-files/files ). With a 1m x 1m s
Well done Stefan,this loaded Q vaue looks very reasonable. 73 Clemens DL4RAJ -- Original Message -- From: [email protected] Stefan Schäfer To: [email protected] rsgb_lf
Hi Stefan, ok,then you've measured the *loaded* antenna Q because the 50 Ohm source of your VFO is included in the circuit. The Q of a LCR circuit is defined Q=f0/B. That formula was derived with a s
Stefan, just to be sure how you have measured Q. If you are feeding the loop with a 50 Ohm source and want to measure the unloaded Q of the loop as per the formula Q = f0/B you would have to look whe
Hello Peter, Tnx for confirmation. Today i bought a new copper tube, circular, 1m diameter and 18mm tube diameter and 1mm thickness (16 EUR). This time i realized excellent contact of the caps dieect
Hello Peter, Clemens, Jim, LF, Before a few days i have bought a new copper tube with 18mm diameter and 1mm thickness. I formed a loop with 1m diameter. This time i put 2 copper plates into the tube
Hi Stefan, Confirming your findings. In the late 90th I built a 2m-loop from 1" coax ("Flexwell") for nulling out Loran-C splatter. I remember a bandwidth of ~12-15 kHz => Q ~= 10 with 8.2uH/165nF. h
Dear Jim, LF, Thanks for the calculations and explanations. By now my loop has a unloaded Q of 230. It is still a prototype and i expect the final Q will be 250. I took the loop to my trip to Hamburg
Dear Stefan, LF Group, A bit late, but better than nothing... One more question: Does it make sense (regarding good SNR) to further try to improve the Q or does it just make frequency adjustment comp
