I have changed the subject heading to better identify the thread: PA0LQ filter descriptions: http://www.alg.demon.co.uk/radio/136/af_filter.htm http://home5.swipnet.se/~w-54761/pa0lq_filter.htm 73 Ch
Most LF PA designs employ FETs in class D push-pull, with the output taken via a transformer. A Pi section filter is then used to remove the harmonics. The documentation on the Decca transmitter mod
James Moritz wrote: snip The main motive for this expedition is to do some back-to-back comparisons between a big antenna (the 100m Decca mast) and a small, amateur-type antenna (an inverted L about
I also experimented with a bridge circuit (a modification of a surplus SMPS, but not using rectified mains). I had a "blow up" and it took out all four MOSFETs. In earlier days for LF transmitting I
Jim M0BMU, Thanks for the further information on the planned tests. With the spacing between big and small masts that you are intending to use, and with the "big" mast being much shorter than needed
phase I have also experienced noticeably easier copy of weak CW in noise when at a distance from the headphones - in fact I find that turning up the AF gain a bit and leaving the headphones on a tabl
Hello Dave and the others, I think that the discussion about antennas with a significant horizontal part is not 'if' they work (they do work, signals of OH1TN, DJ9IE etc. prove so), but 'why' or 'how
Thanks for reading this, I'm doing some study on audio bandpass filters before building a different variant of the PA0LQ stagger tuned filter. Texts suggest that the type of multiple feed back (MFB)
Hi Bob, Bessel filters do have wonderful group delay characteristics, and a bandpass version is entirely mathematically realisable...but not especially useful. I was not planning to use one. My query
There's a nice software called "Filter Wiz Pro" which can be downloaded at: http://www.schematica.com/Fil_Xfer/Transfer.htm The unregistered version has some masked componet values in the circuit dia
Bob: Try the following site - for filter design - I believe you can enter the parameters, and the filter is designed on the spot. FILTERCAD WEB SITE INFO www.linear.com/apps/download.html - download
Hi Bob, "Electronic Filter Design Handbook" by Williams and Taylor has a section on "Capacitive Coupled Resonant" bandpass filters. (These are the kind where a number of parallel tuned circuits are c
g3kev wrote: snip If someone using the new Hydrogen/Stentlesch clock and a b/w of 0.0000000000000000000007 hz told us that they had made the first qso across the atlantic on 136 khz, how would the re
I wish to thank Jim M0BMU for his good summary comments on filter design, including Bessel types. I do not have either of the two reference books Jim named and I will request the public library to se
TRANS-PACIFIC LF TEST SCHEDULE 6 June 2000 Arrangements have been made for a number of West Coast stateside LF listeners to find out what they can receive from ZL LF test transmissions. The timing is
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
Larry, Mentioned for completeness, at the Quartz Hill ZL6QH DX station, of which I am a member, we decided to use high tensile 12 gauge galvanised steel wire for replacement of any of the long Vee an
Regarding selection of JFETs for active antennas, dynamic range tests done some time back by Andrew ZL2BBJ on a selection of JFETs showed that the J310 was generally the best choice. Optimum current
Andy G4JNT and others, Some comments on grappling with PSK keying clicks: considering the key click problem when using BPSK with switching transmitters. Traditionally, amplitude shaping is >used to l
-- Original Message -- My main driver for using a 340V rail was the need to not have to have a separate PA. A 50V 25A PSU is fine if you can get one - I have an old telephone exchange PSU - but norma
