/g/nbems

check VFO accuracy of k3fef remote SDR with FLDIGI

k3euibarry@... (K3EUI Barry) — Sun, 13 Apr 2025 06:18:42 -0700

de k3eui Barry

Kennett Square PA

Due to my high noise level (over S9) on 80m and 40m, I often will use the REMOTE SDR at k3fef.com (NE PA) for digital sound card nets

like the PA NBEMS or MidAtlantic NBEMS.

To check the accuracy of the k3fef radio, I tune it to 14.999 MHz and click on USB (upper sideband)

Since WWV carrier is right on 15.000 MHz, by tuning 1 kHz low on the k3fef VFO, I will hear a steady tone (15.000-14.999)

of 1 kHz or 1000 Hz on the sound card output of k3fef.com on the internet connection.

This is not the beep beep tones that WWV sends out at the start of each second.

This is the steady BEAT FREQ of WWV when the K3FEF VFO is purposely tuned 1 kHz low on the k3fef dial.

That audio from k3fef is piped into a second sound card on my home computer, and I use FLDIGI to monitor that sound.

Choose the Fldigi mode "FREQ ANALYSIS" .

The waterfall of Fldigi shows the steady tone close to 1000 Hz

(it also shows the beep-beep audio sounds +/- 500 Hz off but ignore that)

But if the steady tone is not exactly on 1000 Hz on the FLDIGI Waterfall, then the VFO at K3FEF is off just a bit on upper sideband mode.

(do not use AM or LSB or lower sideband for this test)

I allow the FLDIGI FREQ ANALYSIS mode a minute or so to center in on that steady tone, and it tells me that rather than 1000.00 Hz (if k3fef.com VFO were really accurate)

the the audio is at 1004.689 Hz (see attached image)

So that tells me that the VFO at the remote SDR K3FEF is "off" (high) by about 4 or 5 Hz.

That is, the bfo at that radio at k3fef.com is just a bit "off".

No one likely cares about a 5 Hz "error" at 15 MHz,ut it does throw off copy of MFSK32 signals we use on the NBEMS nets.

I either have to move the center frequency of the FLDIGI WF to the center of the signal coming from k3fef.com

I can adjust the VFO frequency at k3fef.com to compensate for the 5 Hz "error" in that VFO.

Either way works.

Not bad!!

Upgrade or not?

radio-tuber@... (Jim Falls) — Mon, 07 Apr 2025 18:45:02 -0700

2 year old laptop running Windoze 11, wiped and reloaded. Ready for fldigi suite.

I’m currently running
Fldigi 4.2.06
Flmsg 4.0.23
Flamp 2.2.10

All are well behaved and play well with others. Should I use the latest or reload these I have (assuming they’re still available)

Jim Falls K6FWT

Re: [winfldigi] RX/RTX Character Set

w1hkj25@... (Dave) — Sat, 05 Apr 2025 17:41:20 -0700

fldigi 4.2.06.27 development version available for testing

Download at https://www.w1hkj.org/alpha/fldigi/

fldigi-4.2.06.27.tar.gz	2025-04-05 19:38	4.9M
fldigi-4.2.06.27_set..>	2025-04-05 19:38	6.6M
fldigi-dark-scheme.png	2025-03-21 07:41	122K
readme.dmg.txt	2025-03-21 07:41	532
readme.txt	2025-04-05 19:38	877K

commit 39f388baf4b364a4abedc366f7fc7d5d346aadb5
Author: dave-w1hkj <w1hkj@...>
Date:   Sat Apr 5 09:35:00 2025 -0600

    Alpha
    
      * version 4.2.06.27

commit e4ed761d6e6fea3740d70654d5aff2722dcde225
Author: dave-w1hkj <w1hkj@...>
Date:   Fri Apr 4 14:06:16 2025 -0500

    TTY ITA2
    
      * allow user to select USTTY or ITA2 for Baudot shifted characters

73, David, W1HKJ

calibration of sound card timing using a WWV or CHU signal on HF

k3euibarry@... (K3EUI Barry) — Wed, 02 Apr 2025 14:02:35 -0700

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

THOR 32 recd at k3eui on RF Spectrum

k3euibarry@... (K3EUI Barry) — Thu, 27 Mar 2025 18:42:21 -0700

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 modulation

The 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

Re: how good is a rain gutter antenna

krausts@... (Timothy S Kraus) — Thu, 27 Mar 2025 13:03:26 -0700

Barry/KE3UI,

Yes, build a mag loop.

It's sharp tuning will allow you null out the noise.

On twenty, Olivia 8-500 right now, 2003Z.

Kraus/KC4ZGP

Re: fldigi development test version posted

w1hkj25@... (Dave) — Fri, 21 Mar 2025 11:38:04 -0700

Thanks Ken. Only will effect local builds. I will post a 26 tgz in a few.

David

Re: fldigi development test version posted

jj1bdx@... (Kenji Rikitake JJ1BDX) — Fri, 21 Mar 2025 09:14:19 -0700

When trying to build fldigi 4.2.06.25 on macOS 15.3.2 with Xcode command tools, the following error emerged:

  CXX      config_script/fldigi-create_default_script.o
  CXX      config_script/fldigi-run_scripts.o
config_script/run_scripts.cxx:185:10: fatal error: 'scripts.h' file not found
  185 | #include "scripts.h"
      |          ^~~~~~~~~~~
1 error generated.

I couldn't find the file "scripts.h" in the tar archive. Any fixes?

Kenji Rikitake, JJ1BDX / N6BDX

fldigi development test version posted

w1hkj25@... (Dave) — Fri, 21 Mar 2025 05:48:57 -0700

at https://www.w1hkj.org/alpha/fldigi/

fldigi-4.2.06.25.tar.gz	2025-03-21 07:41	4.9M
fldigi-4.2.06.25_set..>	2025-03-21 07:41	6.6M
fldigi-dark-scheme.png	2025-03-21 07:41	122K
readme.dmg.txt	2025-03-21 07:41	532
readme.txt	2025-03-21 07:41	877K

Alpha
* version 4.2.06.24

frequency lock status
* save and restore frequency lock status between sessions

run_script
* add new command line parameter
. script <fullpathname filename>

73, David, W1HKJ

Flmsg ARQ

rwenig@... (Ron NY3J) — Wed, 19 Mar 2025 04:58:45 -0700

Good Morning All,

Our local net has been trying Flmsg ARQ mode. I noticed in the user manual the menu selection is different than my Flmsg version 4.0.23.
The manual has a menu selection titled ARQ and when you select it there are 3 selections, Open/Close, Received Msgs and Events.
On my Flmsg there is a selection called Utilities which only has Received Msgs and Events.
The manual says if you select Open/Close it expands the bottom of Flmsg to include ARQ and the Send button along with the place to enter a callsign.
On my Flmsg the bottom part, ARQ, is always open. I've had stations confused with seeing the Send button and during regular Flmsg transfer hit the Send instead of the AutoSend at the top.
I was wondering if there is a setting that makes the Flmsg program behave the same way as the user manual.

73, Ron NY3J

Re: optimum deviation on 2m FM with THOR22 mode

k3euibarry@... (K3EUI Barry) — Tue, 18 Mar 2025 04:52:42 -0700

I forgot to mention that the fastest Fldigi mode we regularly use on 2m and 70cm FM is 8PSK500F.

That mode is super fast for transferring FLMSG and large FLAMP EMCOMM traffic like Severe Weather Reports, ICS213, American Red Cross Shelter Reports, etc.

Most of the ARES/RACES ops in Chester County (PA) set their radios to 1200 baud TX and RX (pin 5).

Pin 5 provides receive audio similar to speaker audio - de-emphasized at -6 dB per octave from 500-3000 Hz.

But a few have their rigs and sound cards set to 9600 baud (pin 4 on the 6 pin MINI DIN data port) which has no filtering at all and seems “flat�� from 100 Hz to 3000 Hz. (I can see all of the PL tone audio on a graph).

It appears to us that there are no problems with some rigs set to 1200 baud (filtered audio) and some rigs set to 9600 baud (flat audio) although I think it would be ideal for all data rigs to be set to 1200 baud, taking the advantage of filtered RX audio using de-emphasis of the noisy treble audio.

What do ARES / RACES groups who use FM for Fldigi digital sound card modes discover?

What is the optimum mode?

MT63-2000 is very robust, but very slow.

8PSK1000F is very fast, but less robust in the presence of some noise.

Thor and MFSK are easy to use at a variety of speeds.

MFSK128 is superb for images.

de k3eui

barry

Phila region

optimum deviation on 2m FM with THOR22 mode

k3euibarry@... (K3EUI Barry) — Mon, 17 Mar 2025 16:46:07 -0700

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

Re: FLAMP won't transmit file

w0nrp@... (Neil Preston W0NRP) — Sun, 16 Mar 2025 19:09:50 -0700

Thanks for the replies. I found 2.2.14 (even though it still is listed as .13 on the source pages) and have installed it.

We will see if it resolves the problem.

73,
Neil WØNRP

Re: FLAMP won't transmit file

kk5vd@... (Robert, KK5VD) — Mon, 10 Mar 2025 13:32:31 -0700

2.2.13 is broken and should be removed from your system. Use the current version 2.2.14. The last time I checked Dave's website still indicates 2.2.13 is the latest. Which is not the case.
Robert

Re: FLAMP won't transmit file

bob3bob3@... (Bob Cameron) — Sun, 09 Mar 2025 20:54:59 -0700

Hi Neil

I remember this problem to do with flamp 2.2.13 maybe mid last year. Something about a wrong XML response or timing issue? Solved in my case at the time by going back to 2.2.12.4, but now with 2.2.14 and later fldigi alphas (using 4.2.06.24) it all works fine. There may have also been part of the fix in an early 4.2.06.alpha. 24 seems quite bullet-proof so maybe try that along with flamp 2.2.14?

Pretty sure it was discussed in this group July 2024

Cheers Bob VK2YQA

On 10/3/25 13:59, Neil Preston W0NRP via groups.io wrote:

FLAMP won't transmit file

w0nrp@... (Neil Preston W0NRP) — Sun, 09 Mar 2025 19:59:37 -0700

Lately I have been having recurrent problems getting FLAMP to transmit a file.
I load the file into the transmit pane using either DnD or the Add button.
Verify the speed, compression and other functions.

Press XMIT.......... Nothing happens.
This happens with the current version and the previous version.
It seems to be intermittent, but once it occurs it will not work again during the session.
I think that I can trigger it if I cancel a transmission, but most of the time that has not happened.

Using FLDigi v4.2.06 and flamp 2.2.13 on a Win11 machine.
Sorry I don't have more specifics, but if I find any consistent causes I will update.

Any ideas what is happening? It's really frustrating...

73,
Neil WØNRP

Re: audio spectrum of THOR32 sent by W3JFS on CCAR UHF net

k3euibarry@... (K3EUI Barry) — Thu, 06 Mar 2025 18:31:57 -0800

now that I look at it, why are the sidebands not symmetrical at -30 dB?

odd

The huge spike at 100 Hz is the repeater PL tone output

de k3eui

audio spectrum of THOR32 sent by W3JFS on CCAR UHF net

k3euibarry@... (K3EUI Barry) — Thu, 06 Mar 2025 17:47:29 -0800

*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*

Re: how good is a rain gutter antenna

w1hkj25@... (Dave) — Tue, 04 Mar 2025 09:22:14 -0800

The joints at elbows, etc. are usually secured with a single sheet metal screw. Not a very good RF bonding, especially after a few years of rain. There is a strong possibility of arcing at the joint. Probably a good way to discourage TV viewing by your neighbors 😘, The best antenna for low noise reception will be a magnetic loop. I have a homebrew 6 foot diameter loop made from copper pipe, tunable from 40 to 15 meters using a vacuum variable, 100 pf pullout from a Russian radar system. Suggest you check these out:

73, David

how good is a rain gutter antenna

k3euibarry@... (K3EUI Barry) — Tue, 04 Mar 2025 06:55:41 -0800

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