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1500 questions
4
votes
1 answer
How do I set the spectrum scope gain on the Icom IC-7300?
I have an IC-7300.
When observing weak signals, the spectrum scope has signal peaks that are way too small. Just now I was listening to a clearly audible CW signal that was easily heard but hardly moved the spectrum scope at all. I had to squint at…
Xunie
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4
votes
2 answers
Is Army surplus steel wire suitable for an antenna?
I have a whole spool of military communications steel wire that I've been thinking about using to string up a doublet. We used this stuff when I was in the 138th Signal Btn and let me tell you, it's the meanest wire for it's size and weight that…
Dax
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4
votes
1 answer
Really a Class C design?
In the March 2000 QST there was an article on the Tuna Tin QRP transmitter, which I thought I might build:
The text describes Q2 as a C Class amplifier, but I just can't see how that can be true.
"It's ouput (of Q1) tickles the base of Q2 (lightly)…
Ian_B
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4
votes
2 answers
Putting up a tower on my residential property
I live in upstate South Carolina.
I contacted the city and the person who answered the phone call said it would be a new structure and can't be higher the the house on the property.
I looked at the county the city is in and they do not have any…
N4LEP
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4
votes
2 answers
DIY Short Vertical Wire Loaded Antenna: Using 20 Ohm Resister to Widen Q
I've been working with Xnec2c to model a 40 meter vertical antenna I want to build for field QRP. This antenna is short at 25 feet and uses a 1:1 unun at the base with 4 radials.
The model has the load placed 1/4 of the way up (~6 feet). The model…
wbg
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4
votes
3 answers
Why is analog TV vestigal side band and not SSB?
Analog TV signals have one sideband cut off to reduce their (very wide) bandwidth and save frequency space in the ether. The lower sideband is cut off, but not completely, the lower 1.25 MHz is kept resulting in a vestigial sideband signal. I've…
JanKanis
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4
votes
2 answers
Can an 'ugly balun' be too long?
Will an ugly balun exhibit adverse effects if more coax is wound onto it than the recommended 18 - 21 feet?
The antenna in this instance is a 40 Meter Delta Mono Loop that suggests using 22'-6" of 75-Ohm coax to transform the impedance of the…
Dax
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4
votes
1 answer
Digital Protocols, Public Documentation, and Encoded Messages
When is a new digital protocol considered "documented publicly" enough to be used for amateur radio transmissions?
Part 97 states the following about prohibited communications:
(a) No amateur station shall transmit:
...
(4) Music using a phone…
James KE5JOO
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4
votes
6 answers
Do changing sidebands have their own sidebands?
An amplitude changing carrier wave causes sidebands to appear next to it when viewed in the frequency domain. But if those sidebands themselves also change with time (because the modulating signal is not constant), shouldn't those themselves behave…
JanKanis
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4
votes
5 answers
How does one know when band conditions are optimal and what factors to consider?
On many of the DX sites, one will find many variables for solar weather to include flux, A, K, sunspots, etc… I’d like to know how to read those and know what to look for. As I understand it, the sun’s activities affect the ionosphere which affects…
Ender
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4
votes
1 answer
Any way to get LOTW "credit" for a paper QSL card?
I have some QSOs with hams who will send paper QSL cards but do not use LOTW.
I know that if I manage to get a paper card from them I can submit it to ARRL for DXCC credit. But will that QSL show up in LOTW? Or is there zero integration between…
QuantumMechanic
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4
votes
2 answers
How to hook up my computer's audio output to my CB Radio?
I own this simple CB Radio: http://www.cbforumas.lt/upload/manuals/alan/alan_42_um.pdf
I would like to connect its 2.5mm microphone jack and my computer's 3.5mm audio out jack. I have tried simple adapters and cables, but they fail, because the…
Andreas Hartmann
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4
votes
3 answers
What is the difference between antenna input impedance and its radiation resistance?
I got to know that the input impedance of the halfwave dipole antenna is given as:
Zin=1/Im* sin(β(H-|Z|))
where Im is the maximum current on the antenna( when excited with a 1 volt supply),
H is the half-length of the antenna,
Z is the position on…
Moulee
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4
votes
2 answers
VNA basics, antenna coax cable
Recently purchased my first VNA (Nano VNA) and I'm trying to learn the basics.
I have a 150MHz 1/4 wave whip antenna that I need to install on a large metal object so I was hoping to use a VNA to help me understand the performance of the metal…
P_J
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4
votes
1 answer
Phase-tuning Yagi-Uda antennas
Related to my earlier question around the TET-Emtron HB35C antenna. It is advertised as a:
The HB35C is a full size tri-bander, efficiently utilising the DUAL
DRIVE HB9CV system with the revolutionary “PHASE TUNED” VK2AOU multi
band system.
This…
t252
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