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Messages - RobRich

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1
0405z - Music. SIO 544. ~S9+20 peaks via Airspy HF+D and 31' vertical. DSB sync tuning. Moderate static crashing here but otherwise a decent to good copy.
0416z - Station ID
0418z - Music. Switched to the 148' loop-on-ground. Occasional ~S9+30 peaks. Sounding good.
0503z - Music. Still rocking a big signal here.
0543z - Off air.

Thanks for the broadcast! :)

2
Equipment / Re: Optimal EFHW Configuration for Low Angle DX?
« on: June 16, 2024, 1453 UTC »
Correct for those diagrams as published. Red is looking from above. Blue is looking from the side. Also correct on the angle of radiation. Lower towards the horizon tends to improve DX performance.

Note sloping tends to shift the radiation pattern and angle of radiation. Usually you can add or subtract a dB or few towards (or away from) a particular direction if desired. However dropping the lowest end far enough down towards the ground might also start incurring additional ground losses, especially at lower frequencies. YMMV.

Unless looking for NVIS for local to regional work at lower frequencies, a horizontal dipole at approximately 1/2' wavelength above moderate to decent ground can return up to ~8.5dBi of gain. That said I am inclined to say "whatever" to a couple or even possibly a few dB on HF as propagation does much of the heavy lifting anyway. ;)

Looks like KK4OBI did the QSL article:

https://www.qrz.com/db/KK4OBI

If interested enough in the models, EZNEC is not too hard to learn for basic wire antennas.

https://www.arrl.org/antenna-modeling-for-beginners
https://www.eznec.com/

Also correct that an EFHW is a half-wave dipole typically at its lowest frequency. "Typically" as there are ways to add lower frequencies with coils and similar. If just a basic wire, you are end-feeding the half-wave dipole at a voltage node. At higher frequencies, AFAIK, it starts looking more like a collinear dipole array or probably even a longwire as frequency increases.

Since we are on the topic of end feeding, note even an "end-fed" antenna is subject to Kirchhoff's first law, meaning there are still some currents on the transformer side opposite the primary antenna wire. Those currents tend to common-mode couple to the feedline if no other RF ground or counterpoise is available, thus why many recommend placing a simple RF choke a few feet down the feedline from the antenna.

Anyway, do not overthink the antenna modelling for a simple wire HF antenna. Get the wire as high as possible for your deployment situation, and do not be concerned if there is a slight to even moderate slope towards whatever direction. Barring some type of antenna failure, you should be making lots of contacts as an amateur op.... or likewise receiving lots of stations if a SWL.

BTW, if ya' are really wanting those extra dBs of directional gain on a low band like 80m, you might later look into a wire yagi or similar.

3
Equipment / Re: Optimal EFHW Configuration for Low Angle DX?
« on: June 13, 2024, 1245 UTC »
It means a typical horizontal half-wavelength dipole antenna should be (if possible) mounted as high as it is long. To be more technical it is the half wavelength of the tuned frequency instead of the antenna's physical length.

For example a typical 40m dipole at ~66' total length would offer good overall performance when mounted horizontally at ~66' height versus a lower height.

That said and factoring the "more technical" aspect, ~66' height would still be applicable even if using loading coils to shorten the antenna to say 33' total length.

Actually there can be lots of other considerations like NVIS at lower frequencies, but anyway, it is a good basic guideline for typical HF half-wave dipoles.

Even a multi-band "EFHW" is still a dipole; just a extremely offset fed one. Getting an 80-10 EFHW up ~133' for 80m is probably not happening for most, thus like most things radio, actual height will be a compromise for your particular deployment situation.

Even if just a few feet off the ground, any antenna tends be better than no antenna. At the extreme, people have worked HF contacts with wires on the ground.... and even on dummy loads. ;)

5
2214z - Carrier in waterfall. No discernible modulation. Airspy HF+D and 31' vertical.

6
Equipment / Re: Best MWDX antenna?
« on: June 10, 2024, 2144 UTC »
AFAIK, lots of Icom HF models from that era have the jumper arrangement. It is a good place to add a preselector, MW highpass filter, etc. without having to use extra RX/TX switching.

That said, I think ya' meant to post here....

https://www.hfunderground.com/board/index.php/topic,130371.0.html ;)

7
 0433z - Music. SIO 333 trending 322. Airspy HF+D and 148' loop-on-ground.
0436z - Moved to 6940....

https://www.hfunderground.com/board/index.php/topic,130318.0.html

0443z - Back to 6955. Sound effects.
0444z - OM talking? Under static crashing here.
0446z - Slightly above 6955? Sound effects.
0450z - On 6955 now or at least close enough. Sound effects. Signal improving. SIO 333.
0454z - Moving up and down frequencies then back to 6955.
0458z - Peanut Butter Jelly Time under the sound effects.
0501z - ~6955.05 with music. Audio seems quite bandpassed; especially on the low frequency side.
0505z - OM under static crashing? OM modulation drops too low for copy here.

Seems the OM talk is more likely unrelated peskies in the noise floor.

8
0428z - A couple of music clips. More like 6940.25 or so. Airspy HF+D and 148' loop-on-ground.
0430z - Signal moving up and down frequencies.

Related:

https://www.hfunderground.com/board/index.php/topic,130320.0.html

0439z - Back to ~6940. Rough copy. OM taking.
0440z - Music. Modulation improved. SIO 333.
0443z - Back to ~6955.

9
0423z - Various sound effects. Airspy HF+D and 148' loop-on-ground.

10
Amateur Radio / Re: Suggestoins on headphones for listening
« on: June 09, 2024, 0318 UTC »
Sadly we can also get an increased noise floor and hiss, including both well beyond the desired frequency ranges, from the audio stages of whatever connected devices. Cheap opamps, cheap caps with lose tolerances, etc. are far too common; sometimes even in pricey gear. Good headphones or speakers can bring more attention to such issues.

My previously-mentioned Etymotic ER3SE IEMs can occasionally point out audio source issues with connected devices. Thankfully I have an old first-gen FiiO E10K DAC/amp available at least for computer-based listening.

Speaking of actual headphones, I like my old Monoprice Stage Right reference headphones for shortwave listening. Closed-back design with moderate isolation. Decent mids (IMO) without a huge bass bump in the frequency curve. On the downside they are discontinued. Mine get plenty of use here. My pair is needing new pads right now.

11
Amateur Radio / Re: Suggestoins on headphones for listening
« on: June 06, 2024, 2302 UTC »
Kenwood HS-5 headphones are highly rated and designed specially for voice comms listening. They are mono audio, have an 150-4000Hz frequency response, and low 8-ohm impedance for easy driving. The design is time tested as they have been in production for decades now.

https://www.eham.net/reviews/view-product?id=1075

Do note the HS-5 is an open-air design, so that might be concern if you are seeking improved sound isolation.



I find Panasonic ErgoFit wired earphones at ~$10 to suffice for my typical shortwave listening, plus even everyday music sounds decent enough for casual listening IMHO. Also they come with three sizes of eartips, so you can better tweak fit and sound isolation.

https://www.amazon.com/dp/B003EM8008

Admittedly I like my Etymotic ER3SE balanced armature IEMs (using foam eartips) as well, but somewhat delicate $150+ earphones are kind of ridiculous for shortwave listening IMHO. I am unlikely to ever take them with a portable radio to a beach, park, etc. Also they for designed for a perceptibly flat frequency response curve, which admittedly some people do not actually like for ear/headphone listening.

https://www.etymotic.com/product/er3se-earphones/



Regardless if ear/headphones or speakers, I sometimes use software audio DSPs like EasyEffects and StereoTool for additional equalization, pass filtering, noise filtering, etc.

There are also standalone filters designed specially for CW and voice comms listening. Some are basic, even analog solutions for as simple as additional pass filtering. More complex digital DSP solutions might include pass filtering, noise reduction, etc. I still have a couple of old Timewave DSP-9 digital filters that I often used for SSB listening with my Kenwood desktop receivers. bhi Ltd and West Mountain come to mind for more modern DSP offerings.

12
Equipment / Re: Best MWDX antenna?
« on: June 04, 2024, 2236 UTC »
Now this one is interesting. Paru (Arch AUR app) built an updated SDR++ checkout earlier today, and it has started reading signals around 10db or so lower than GQRX and SDRSharp. Tested against my Airspy HF+D.

Same FFT size for all three. Window algorithms are different but not that much different.

Checked recent SDR++ commits. Nothing stands out in a (very) quick skim.

Reported SNR values are about the same, so I am not too concerned; just kind of a "Hmmm...." situation.

13
Interestingly, it might be both. According to....

https://shortwaveschedule.com/index.php?station=407

6180KHz = 250KW
11780KHz = 100KW

14
I have not bothered checking my clock for a signal, but I did note WWVB with a S4 signal over an S1 noise floor this morning at 0908z via my usual Airspy HF+D and 31' vertical

Anyway, glad to know the south antenna is being fixed.

15
Shortwave Broadcast / RN da Amazonia 6180 AM 0852 UTC 4 JUN 2024
« on: June 04, 2024, 0856 UTC »
Talk over background music at 0852z into music. SIO 222 via Airspy HF+D and 31' vertical LSB sync tuning due to Radio Educacion on 6185am. Considerable static crashing and rather weak signal, but it is there. Verified against the station's online stream.

Reportedly 250KW from Brazil.

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