Most Popular
1500 questions
5
votes
2 answers
Is tuning at all useful for an antenna that is already resonant?
Say you have a resonant antenna that also has a tuner. Does this help at all? Can your antenna be "fine tuned" ?
NonYaBidnezz
- 353
- 2
- 10
5
votes
1 answer
Are there an MTTF/MTBF/MTTR data on the typical tubes used in the FT-101/TS-520?
I browse ebay.com for used rigs in good condition and approaching my shoe-string and ... There appear to be a decent quantity of boat anchors out there - FT-101, TS-520, TR-4 to name just a few.
By definition, a boat-anchor would date to the…
VU2NHW
- 2,844
- 2
- 23
- 43
5
votes
1 answer
Can a 1A Field Day station qualify for the "Alternate Power" bonus?
We just finished our Field Day operations, and we're having a disagreement on whether we qualify for the Alternate Power bonus. Our 1A (single transmitter, emergency power) station was completely solar powered for the duration of Field Day, which…
W5VO
- 1,941
- 1
- 13
- 24
5
votes
1 answer
How to center-feed a single wire dipole?
I have heard that it is possible to feed single wire like a dipole from the center-point without actually making two separate wires.
How would I do this, what impedance would I expect to see, and what matching technique should I use to keep it at…
Skyler 440
- 7,690
- 9
- 54
- 90
5
votes
2 answers
Phased array (rx only) with separate complete receivers
Is it possible to have a network of separate (but co-located) 'receivers' (antenna + adc) act as a phased array receiver?
Supposing one can get very precise timestamping on each receiver, couldn't all the receivers be assembled as a phased…
5
votes
2 answers
How does the material of a fishing-pole mast affect antenna performance?
I'm a newly-licenced ham and currently starting out with HF.
My home doesn't allow for a permanent setup. I can therefore only operate portable from parks and such, with limited TX power (my rig goes up to 20W), so an efficient antenna seems…
Ivan R2AZR
- 469
- 4
- 13
5
votes
5 answers
Do modern radios and power supplies require grounding for safety?
Do modern radios require grounding to be used safely? All I am concerned about is not getting electrocuted when I attempt to use the radio. I'm not concerned with RFI or Lightning safety at this point in time.
The power supply apparently has a…
Nick H
- 153
- 1
- 6
5
votes
1 answer
EFHW: better to get far end really high, or middle somewhat high?
I built a 40m end fed halfwave antenna and unun, and the wire is about 66 ft long. I have some tall trees nearby I can hang it in, semi-permanently.
Which of the following would be better?
A) hanging the far end nice and high, about 50ft, but then…
User5754448
- 448
- 4
- 12
5
votes
1 answer
Using a Return Loss Bridge and Nano VNA to measure amplifier characteristics
One of the difficulties of measuring active devices like LNA and IF amplifiers with the Nano VNA is the care needed to avoid over-driving the amplifier input and, more importantly perhaps, to avoid blowing up the CH1 port during S21 (gain)…
Buck8pe
- 989
- 5
- 17
5
votes
2 answers
Why am I not hearing repeater identification more often?
I just bought a 2m/70cm handheld. I programmed in the local repeaters and have been scanning them for a couple of days. Only about twice have I heard one of the repeaters come up and identify itself. From reading, my understanding is that the…
plafratt
- 229
- 3
- 7
5
votes
1 answer
Looking for a model or description of an EME channel
I am looking for any technical/scientifical/specialized reference describing in some detail the moonbounce for VHF/low UHF frequencies.
More precisely, I would be interested in a paper or publication describing some aspects such as the dispersion…
user3141592
- 276
- 2
- 9
5
votes
2 answers
Can coax be run through the center of a radiating element without currents being induced on the coax shield?
I run a λ/2 vertical dipole for 20M that's fed to a 1.5:1 balun at its center with coax that is perpendicular to the dipole (parallel to the ground), for about 30 feet before it comes down to the shack. I wanted some opinions about what would…
Louis Seaman
- 1,058
- 3
- 10
5
votes
2 answers
LOS One-way radio system, 4km with at least 1000bytes/s
In order to track skydivers/BASE-jumpers with flysight I am looking for a one-way radio system to transmit the location data. System needs the following specifications:
Frequency: Not important, preferable legal (Europe)
Bandwidth …
wittrup
- 153
- 4
5
votes
2 answers
CHIRP on Mac in 2021
Has anybody had success in running CHIRP on a modern Mac? I am running OSX 10.15.7 and the download I found for Mac looks like just source code, no app file at all. I'm considering trying a build from source code, but before I get into that let me…
Randy L
- 153
- 1
- 6
5
votes
1 answer
MF band mixer - feasible parameters
Trying to build an homebrew receiver for MF band broadcast (Navtext).
Usually working on VHF, where all parts are easily found as an IC, but here I'm trying to get back to roots, so I may be missing something.
I'm considering a superhet schema and…
gusto2
- 153
- 3