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The last sound card to calibrate via the Fldigi WWV mode is a 10 yr old USB Sound Blaster that has very low noise. I usually use this sound card with a RSPduo SDR (hardware) which tunes HF, VHF, UHF and all modes. Right now, this is set to CHU Canada on 7850 kHz upper sideband with a 2 kHz filter BW. Fantastic signal into the Phila region of SE Pa. After setting the sample rate to NATIVE and the corrections in Fldigi to 0 ppm, the result was nearly perfect after ten minutes. So all of my sound cards now have "calibrations" in ppm with the largest one +65 ppm. Has anyone found a large calibration correction (hundreds of ppm) using the WWV (5, 10, 15, 20 MHz) or CHU (7850 kHz) time ticks? de k3eui

Tonight we used THOR 32 mode on the CCAR UHF FM net. (Chester PA) Thor modes consist of 18 tones, sent one at a time, at 32 baud. This is a modest audio bandwidth - about 600 Hz. Here is what the RF Spectrum looks like, received on a SDR in Kennett Square. Spectrum Analyzer is by Andrew (free). You can clearly see the first three "sidebands" on this FM modulationThe modulation around the carrier is the PL tone sidebands of 100 Hz The 8 kHz is just for scale - not the true bandwidth. de k3eui barry2

RAIN GUTTER ANTENNA on upper HF bands I've been experimenting with a variety of HF antennas here at my new QTH at Crosslands Retirement Community in Kennett Square, PA. I have some space limitations, but live on the first floor of a two-story apartment building. Lots of RFI from everywhere inside the building - S9 on 80m and 40m, less noise on 20 and 10m. I have a 140 ft end-fed wire with a 49:1 UNUN which tunes up easily on 80/40/20m and not so well on 17m/15m/10m. This end-fed is horizontal, low to the ground (winds among trees) and is good for high-angle NVIS radiation on 80/40m. I use it on the PA NBEMS net (3583 kHz) and on the Mid-Atlantic NBEMS net (7068 kHz) I'd like to get up something with a low-angle signal for DX on 20/17/10m bands. But can I keep any HF antenna "hidden"? What I am now trying is the aluminum rain gutter for our building, vertical for about 20 ft, makes a right angle turn and runs horizontally for about 20 ft. The coax attaches at the base of the gutter, near ground, to a 9:1 UNUN with a sheet metal screw into the gutter for a decent electrical connection. So overall, about 40 ft of thick (painted) aluminum gutter radiating element - in the shape of an inverted L and not resonant on any ham band. Lowest SWR around 16 MHz. It looks like it might work out on the 30m band as well (10.1 MHz). I have a Palomar Engineering (500W rating) 9:1 UNUN on 50 ft RG8X coax into the shack (closet). I have one counterpoise wire about 20 ft long attached to the UNUN ground terminal. Then a good manual tuner in the shack to an HF rig for very low SWR on any band. Here is what I see on my Nano VNA from 10 - 30 MHz: not bad SWR (under 2.5:1) in the shack on 20/17/15/10 meters. I'll give it a try over the next few weeks and see if the local noise is more/less on these bands, compared to my 140 ft end-fed. I'm often running QRP on these bands, CW and digi modes only. de k3eui barry

Setting up your 2m/70cm FM rig with an external Sound Card It is easy to under modulate or to over modulate an FM rig with an external sound card. If you can monitor your own signal, the old guideline was that the sound card audio should be NO LOUDER than the audio with your own microphone using your own voice. But that is very crude. Sounds like VARA FM and 8PSK do not sound anything like a human voice - so begin with a simple TUNE signal. Here is an optimally modulated THOR 22 signal sent on 2m FM (145.690 MHz) with an Icom 2820 dual-band FM rig and a DRA SR (Masters Communications sound card). The THOR22 audio is centered at 1500 Hz on the Fldigi waterfall. RF Spectrum interpretation: When the amplitude of the RF carrier (vfo at 145.690) equals the amplitude of the pair of first sidebands (+/- 1.5 kHz from carrier) then the "MODULATION INDEX" is 1.5 (Bessel method) The DEVIATION of the signal is established as the product of the modulation index multiplied by the audio frequency. Using the 1500 Hz TUNE in Fldigi, that comes to a deviation (1.5 x @1500 Hz audio) of 2.25 kHz (a bit conservative) Since this signal was sent with the Icom 2820 set to 1200 baud (TX) then the radio's transmit "PRE-EMPHASIS" will add amplitude to higher pitch audio at a rate of + 6 dB/octave. So the deviation is a bit more for any audio at 2000 Hz, a bit less for any audio at 1000 Hz, if the mode is that wide (say a 1 kHz mode like MFSK64) But since THOR22 is only 500 Hz wide, this "pre-emphasis" of the TX signal at 1200 baud plays almost no role. The deviation is about 2.2 kHz for the entire THOR22 signal. The width marker (12 kHz) on the image is just for SCALE value - not a true bandwidth. Note each additional sideband pair is WIDER - how come? We can use the first Saturday of each month for those ops in the Phila region to test their 2m FM deviation using the repeater on 147.270 (N3KZ) with a PL 77 Hz on the input only. But NOT in April due to a SET exercise. de barry2 k3eui

*On tonight's CCAR UHF FM net (446.525) the net control took checkins with THOR32* *I don't think I've ever seen THOR32 on FM nets (18 tones sent one at a time at 32 baud) * *It was fast, clean, and sounded great.* *Here is the AUDIO spectrum (not the RF spectrum) captured by the FLDIGI Audio Spectrum option* *I am receiving this at 9600 baud (pin 4 on the 6 pin MINI DIN data port) or wide flat audio * *and sound card is a DigiRig Mobile V1.9 (which works very well with the Icom 2820 rig)* * * *de k3eui barry2*

at http://www.w1hkj.com/alpha/linsim/ linsim-2.0.5.03.dmg linsim-2.0.5.03.tar.gz linsim-2.0.5.03_setup.exe readme.dmg.txt readme.txt EVENTS * add event log dialog * fix exit thread handler bug * add events OFFSET correction * change sign of correction * correct resampling of source wav 73, David W1HKJ

Hi All, I use the Fldigi log when I'm net control. I have several duplicates of calls. I was wondering if there's an easy way to edit the .adi file that Fldigi creates so I can delete the duplicates and maybe change information or add information. If I use a text editor it just too hard to edit. 73, Ron NY3J

The ALPHA FLDIGI (4.2.06.19) as of Jan 05 2025 The THOR alpha (test) modes now have the OPTION to include "signal shaping" from 0-8 milliseconds. This is the rise/fall time of each tone change. It should operate in a similar way that the CW carrier shaping limits the CW bandwidth and reduces "key clicks" (older rigs). Can we "see" or hear the changes when THOR signal shaping is turned ON or OFF? Here is THOR TX tone rise/fall times signal shaping set to a 0 ms rise time (no signal shaping at all) in the Fldigi MENU Here are the OSCILLOSCOPE trace (on Fldigi WF) and the RF Spectra captured when I was sending a THOR25 signal without signal shaping. I can't hear the difference (in headphones) but the RF Spectra trace does show a cleaner skirt on the RF signal. The OSCILLOSCOPE trace has obvious differences in the tone change amplitudes. No signal shaping Oscilloscope Trace of THOR25 (signal amplitude vs. time) THOR 25 RF Spectra reveals an 800 Hz BW at -30 dB below the peaks. Now with an 8 millisecond signal shaping turned ON (TX tone rise time (milliseconds) Note: using THOR 25 (25 tones/second) EACH tone DURATION is 1/25 or 40 milliseconds. Oscilloscope Trace: each tone is about 40 milliseconds with an 8 ms rise/fall time The RF bandwidth of THOR 25 is reduced by about 100 Hz (@ -30dB down) from 800 Hz to 700 Hz due to the tone "shaping"