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1500 questions
4
votes
1 answer
How to correctly model a small helix antenna
I am getting weird results trying to model a small 433 MHz helix antenna similar to this one with 4nec2:
In particular I am not able to obtain a resonable SWR value.
This is the antenna an example of the nec file.
CE
SY L=0.0205 'Length of helix
SY…
stenio
- 143
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4
votes
2 answers
How do you log (or not) "busted" FT8 QSOs?
When do you decide (when NOT in a contest) to log an "incomplete" FT8 QSO? For example, something like this:
CQ HIMHIM EM00
HIMHIM MEMEME FN00
MEMEME HIMHIM -07
HIMHIM MEMEME R-09
HIMHIM MEMEME R-09
HIMHIM MEMEME R-09
(and then both sides…
QuantumMechanic
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4
votes
2 answers
How to apply for the ARRL WAC award?
I've managed (thank you FT8!) to have LOTW-confirmed contacts with the 6 applicable continents.
However, on reading the ARRL page for the WAC award it says that you have to apply on paper and that LOTW contacts do not count but contacts in your DXCC…
QuantumMechanic
- 893
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- 8
4
votes
1 answer
SSB Single Conversion Superhet 2nd Mixer IF Termination on Transmit
I have a question about "best practice" in regards to how the 2nd mixer IF port is coupled to (in my case) a 20m double tuned filter on transmit.
I'm currently building out the transmit chain for a 20m single band SSB transceiver and I've got as far…
Buck8pe
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4
votes
2 answers
Mounting a hex beam on top of a high urban building
I am moving into a new apartment in the city soon which is on the 24th and last floor of an apartment building. I will have access to the roof of the building also.
I'm still trying to understand antenna theory fully.
I am very tempted to buy one of…
Engineer999
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4
votes
1 answer
What is the etiquette for answering real world, non-contest HF SSB calls?
I'm a new ham (licensed back in the spring) and very new to HF (only a couple of weeks). One thing I've noticed in the phone bands is that things seem to rarely go the way all the articles aimed at new hams say.
For example, I don't hear much CQ at…
QuantumMechanic
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- 2
- 8
4
votes
2 answers
Why does a sine wave show two peaks in the frequency domain on GNUradio?
I constructed the flow graph in GNUradio 3.7 as below:
I know a sine wave has only one frequency, so what causes the frequency sink to show two peaks?
kittygirl
- 600
- 2
- 10
4
votes
1 answer
Why doesn't GNU Radio Companion's wx Constellation Plot doesn't give me the clean QAM constellation I get from its Qt sibling?
Using a RTL2832U USB dongle, I set up GNU Radio to produce a constellation plot of APRS traffic on 144.8 MHz. The result is what I expected:
So far, so good. Why not try the same thing using the wx GUI instead of the Qt version I had used ? Here…
Jean-Marc Liotier
- 141
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4
votes
3 answers
SSB demodulation
I was building the superhet receiver for ham radio. But I seem to have got stuck at the demodulation stage.
As an example:
Suppose the person is transmitting SSB signal (20m band) at 14.250 MHz carrier frequency.
Let the speech signal occupy…
Plutonium smuggler
- 143
- 3
4
votes
1 answer
Does a larger Biquad antenna give better results?
Consider a biquad antenna used for receiving, not for sending. They are typically built with each side having a length of $\lambda / 4$.
If a biquad antenna was built with a side length of $\lambda / 2$ or even $\lambda$, would this give better…
Martin
- 143
- 4
4
votes
1 answer
For Linear Transponder satellites, do I transmit on USB or LSB?
I'm in charge of our Field Day satellite communication, and I'm going to try and do this via SSB on one of the SSB satellites. I know they invert the signal, but is the convention to transmit on USB and receive on LSB, or the other way around?
PearsonArtPhoto
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4
votes
1 answer
Gnuradio bandwidth of sink cause signal frequency changed?
System is debian 10 with gnuradio 3.7.
untitled.grc create simple flow graph as below:
The only difference between 2 flows is bandwidth of gui sink,cause 2 different signal frequency as below:
Why Gnuradio bandwidth of sink cause signal frequency…
kittygirl
- 600
- 2
- 10
4
votes
1 answer
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
- 457
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4
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
- 143
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4
votes
1 answer
What type of antenna are these?
On top of a mountain in south Salt Lake City, Utah there are many antennas.
What are these curly ones?
spuder
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