1246
10/11 meters / Re: Venezuela 27.595 USB 2108 UTC 29 May 2021
« on: May 29, 2021, 2121 UTC »
Sounding like South America freebander DX on the popular 27.555 USB, too.
Shortwave Pirate Radio In North America And Around The World, And Other Signals That Go Bump In The Night
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1247
10/11 meters / Venezuela 27.595 USB 2108 UTC 29 May 2021
« on: May 29, 2021, 2117 UTC »
Freebander operating from Venezuela on 27.595 USB. Good signal. Was working essentially a small DX pileup.
Actually bothered hooking up my Shakespeare 318-GBT 18' end-fed vertical ground mounted over eight 9' radials to skim upper HF today. The feedline to it largely goes unused for long periods of time.
Actually bothered hooking up my Shakespeare 318-GBT 18' end-fed vertical ground mounted over eight 9' radials to skim upper HF today. The feedline to it largely goes unused for long periods of time.
1248
Equipment / Re: Best MWDX antenna?
« on: May 29, 2021, 2041 UTC »
I used an 148' run of RG-6 as a wire-on-ground for years. Fed the center at one end, and shorted the other end back to the shield. I am not sure there was any improvement over just a piece of wire, but I had lots of coax going unused.
Fed it straight, with an 1:1, and with a 4:1. Did not seem to make much difference IMO. I went with a straight feed. No common mode choke at the feedpoint, either, so the feedline shield was the other part of the antenna. Worked okay enough for my purposes from MW through mid-HF at the time.
Fed it straight, with an 1:1, and with a 4:1. Did not seem to make much difference IMO. I went with a straight feed. No common mode choke at the feedpoint, either, so the feedline shield was the other part of the antenna. Worked okay enough for my purposes from MW through mid-HF at the time.
1249
Equipment / Re: Best MWDX antenna?
« on: May 29, 2021, 0317 UTC »
My second active mini-whip arrived. Now to take a portable to the backyard and hopefully find a couple of relatively RFI quiet spots to place them.
I am a little more concerned about placement than usual as small active verticals are essentially e-field probes. Even a foot or two difference can change coupling to local noise fields.
Get them deployed, then see how well my phasing unit can effectively utilize the small array.
I am a little more concerned about placement than usual as small active verticals are essentially e-field probes. Even a foot or two difference can change coupling to local noise fields.
Get them deployed, then see how well my phasing unit can effectively utilize the small array.
1250
Equipment / Re: Best MWDX antenna?
« on: May 25, 2021, 0451 UTC »
Not sure when he started offering them, but ra0sms now has a flag/pennant antenna kit on eBay. :)
https://www.ebay.com/itm/201553084711
Same but with an 1-4MHz bandpass filter.
https://www.ebay.com/itm/202274557903
https://www.ebay.com/itm/201553084711
Same but with an 1-4MHz bandpass filter.
https://www.ebay.com/itm/202274557903
1251
North American Shortwave Pirate / Re: UNID 6925.4ish AM 2120 UTC 23 May 2021
« on: May 23, 2021, 2135 UTC »
Carrier in the noise floor…. maybe. HF conditions have been rather tough this afternoon here, too.
1252
Equipment / Re: Best MWDX antenna?
« on: May 23, 2021, 1923 UTC »
I thought about ADS-B back when the RTL-SDR landed. I just never got around to it. Some day perhaps.
I largely dropped out of the UHF scene when public services and similar went digital.
Be careful or next you might have a Ku dish on a motorized mount…. and looking for somewhere to put the C-band.
I largely dropped out of the UHF scene when public services and similar went digital.
Be careful or next you might have a Ku dish on a motorized mount…. and looking for somewhere to put the C-band.
1253
Equipment / Re: 630M Loop on the Ground (LoG) antenna
« on: May 23, 2021, 1916 UTC »
Dropping a little further down in frequency, I use my 148' coaxial "shielded" LoG for listening to longwave broadcasters when conditions permit.
No matching. No preamp needed for longwave, either. Just straight to the coax. I do have a few snap-on ferrites on the feedline, plus a decent RF choke near the receiver end.
I should get around to parking a SDR on the 630m and recoding a day or two to check reception.
No matching. No preamp needed for longwave, either. Just straight to the coax. I do have a few snap-on ferrites on the feedline, plus a decent RF choke near the receiver end.
I should get around to parking a SDR on the 630m and recoding a day or two to check reception.
1254
Equipment / Re: Best MWDX antenna?
« on: May 22, 2021, 2205 UTC »
20+ years ago I likely would have been there with ya' regarding hardware. :)
Radio is a part-time hobby for me these days, with HF as my only significant particular interest. That is before even factoring costs versus diminishing content and increasing noise floors; both local and environmental.
Admittedly, at VHF and above I too would be more inclined to spend money on better hardware. Just not much that interests me up there.
Radio is a part-time hobby for me these days, with HF as my only significant particular interest. That is before even factoring costs versus diminishing content and increasing noise floors; both local and environmental.
Admittedly, at VHF and above I too would be more inclined to spend money on better hardware. Just not much that interests me up there.
1255
Equipment / Re: Best MWDX antenna?
« on: May 21, 2021, 0138 UTC »
True enough, though the preamp in mini-whips tend to pull double duty as both a matching device and gain amplifier. Someday I might actually try a VNA plot of a like 6" strip on HF and lower, though I already can imagine the extreme loading characteristics.
Most of these cheap eBay preamp boards appear to be MMIC-based chips. I was looking at the INA-02184 for a potentially close match to the 60dB boards I received. Actually probably more like clone chips of an INA-02184 or similar MMIC amp, but anyway.
https://www.qsl.net/n9zia/metricom/ina02184.pdf
The gain and noise factor profiles are rather flat under ~300MHz. Rated voltage max also is 7v, which also seems rather typical for these cheap MMIC amps despite sellers claiming 12v. ?! Yeah, 12v might slam the gain, but the NF tends to improve at lower voltages as many of us have already found. No wonder.
I had been using 9v batteries for temporary deployments of the single-chip 30dB preamp model, but think I will drop voltage further down in future testing of both single- and two-chip models.
Most of these cheap eBay preamp boards appear to be MMIC-based chips. I was looking at the INA-02184 for a potentially close match to the 60dB boards I received. Actually probably more like clone chips of an INA-02184 or similar MMIC amp, but anyway.
https://www.qsl.net/n9zia/metricom/ina02184.pdf
The gain and noise factor profiles are rather flat under ~300MHz. Rated voltage max also is 7v, which also seems rather typical for these cheap MMIC amps despite sellers claiming 12v. ?! Yeah, 12v might slam the gain, but the NF tends to improve at lower voltages as many of us have already found. No wonder.
I had been using 9v batteries for temporary deployments of the single-chip 30dB preamp model, but think I will drop voltage further down in future testing of both single- and two-chip models.
1256
Equipment / Re: Best MWDX antenna?
« on: May 20, 2021, 2323 UTC »
I received a couple of the <2GHz 60dB preamps floating around Amazon, eBay, etc. It is basically a 2-chip cascaded version of the similar inexpensive 30dB preamps.
At first flance I suspect the listed upper voltage limit could be incorrect. 12v probably will not damage them, as I have ran that through the older 1-chip 30dB preamps for short periods, but most of these cheap MMIC-based preamps without voltage regulators likely are rated for more like 4-7 volts to optimize the noise factor.
Anyway, having upwards of ~60dB gain might prove interesting if deploying a high-loss antenna designed for SNR like some of the designs we have discussed here.... assuming the local noise floor is low, the preamp noise factor is not ridiculous, and there is a decent impedance match on both sides of the preamp.
At first flance I suspect the listed upper voltage limit could be incorrect. 12v probably will not damage them, as I have ran that through the older 1-chip 30dB preamps for short periods, but most of these cheap MMIC-based preamps without voltage regulators likely are rated for more like 4-7 volts to optimize the noise factor.
Anyway, having upwards of ~60dB gain might prove interesting if deploying a high-loss antenna designed for SNR like some of the designs we have discussed here.... assuming the local noise floor is low, the preamp noise factor is not ridiculous, and there is a decent impedance match on both sides of the preamp.
1257
Equipment / Re: T2FD results (58 ft)
« on: May 20, 2021, 2224 UTC »
You had a linear-loaded dipole probably resonant somewhere around 5-6MHz.
Given the 58' footprint your T2FD should start rolling off well above MW. The balun might even help with the MW station, as like Chris noted, your coax - especially at 175' and even more so if unburied - is acting as part of the antenna right now due to a lack of common mode isolation.
You might want to wind some coax on a mix 31 or 43 ferrite as a choke closer to the the receiver end, too.
http://www.karinya.net/g3txq/chokes/
Given the 58' footprint your T2FD should start rolling off well above MW. The balun might even help with the MW station, as like Chris noted, your coax - especially at 175' and even more so if unburied - is acting as part of the antenna right now due to a lack of common mode isolation.
You might want to wind some coax on a mix 31 or 43 ferrite as a choke closer to the the receiver end, too.
http://www.karinya.net/g3txq/chokes/
1258
Equipment / Re: Interesting Chinesium SI4732 Shortwave/Air/FM
« on: May 20, 2021, 2217 UTC »
I could have tried adding similar filtering at the USB port or voltage regulator(s), but I left those alone for now due to soldering on smaller pins plus not wanting to accidentally disturb the ability to USB flash firmware. I know a random USB charger was rather noisy on MW+HF as expected. I have been using it on battery power, though no real idea on runtime as I have been charging it between uses instead of letting it run down.
I have thought about looking into a speaker replacement as it seems rather narrow. "Okay" for talk and voice comms. Not so great for music, though admittedly that might be more a function of the audio circuit than the speaker. Suppose I should get around to hearing how it sounds with headphones to get a better idea.
I have thought about looking into a speaker replacement as it seems rather narrow. "Okay" for talk and voice comms. Not so great for music, though admittedly that might be more a function of the audio circuit than the speaker. Suppose I should get around to hearing how it sounds with headphones to get a better idea.
1259
Equipment / Re: Interesting Chinesium SI4732 Shortwave/Air/FM
« on: May 20, 2021, 2104 UTC »
Thanks. The receiver still works, so at least that is something. ;)
IIRC, all the power pins - except the USB port of course - at the Arduino Nano clone read around 3.x volts. I suspect the control board and Si chip are being run at ~3.3v operation.
The Si4732 is rated down to 2.7v, and apparently the Nano's controller can go down to 3.3v or perhaps lower without much issue, especially if it is not being pushed hard.
IIRC, all the power pins - except the USB port of course - at the Arduino Nano clone read around 3.x volts. I suspect the control board and Si chip are being run at ~3.3v operation.
The Si4732 is rated down to 2.7v, and apparently the Nano's controller can go down to 3.3v or perhaps lower without much issue, especially if it is not being pushed hard.
1260
Equipment / Re: Interesting Chinesium SI4732 Shortwave/Air/FM
« on: May 18, 2021, 2003 UTC »
I did not spend much time delving into the design. I just went with the quick-and-dirty approach of throwing parts at it. ;)
https://imgur.com/a/Tn7VvpR
Those are 47uF electrolytics and .1uF ceramics on the Arduino Nano (clone) power rails.
Crossed 1N4148 diodes and a 1M carbon resistor at the BNC connector.
BTW, yeah, my soldering "skills" are horrid. I do good to type sometimes; less long solder anymore.
https://imgur.com/a/Tn7VvpR
Those are 47uF electrolytics and .1uF ceramics on the Arduino Nano (clone) power rails.
Crossed 1N4148 diodes and a 1M carbon resistor at the BNC connector.
BTW, yeah, my soldering "skills" are horrid. I do good to type sometimes; less long solder anymore.
