All Questions
4,661
questions
0
votes
1
answer
29
views
what frequencies can a gnss antenna pick up?
Am sure that gnss antenna can pick up other frequencies than gnss ones, so is there anyone who tested that theory?
- 1
0
votes
1
answer
29
views
Can I operate in AM mode using an Alpha 78 amplifier?
I don't have any experience with amplifiers. I bought my first one last year, a used Alpha 78. I cannot find anywhere where it explicitly states that you can use the Alpha 78 in AM mode. I suspect it'...
1
vote
1
answer
86
views
What can you do to prevent exposure of RF?
When I bought my transceiver, I found out that it only puts out less than half a watt (which can't travel a 1 mile radius from the antenna, according to google). So, I bought a power amplifier. It ...
- 73
3
votes
1
answer
301
views
What is the antenna design and gain for the WA1 U/V band antenna on the ISS?
My son KJ7NLL is working to contact the ISS using an antenna we built together, and we were wondering the approximate minimum transmission power to reach the ISS. If I understand correctly (and ...
- 723
0
votes
0
answers
28
views
Take The HAREC exam in spain in english [duplicate]
I am looking to take the HAREC exam but I have a dilema, I currently live in Spain and my Spanish language skills are not that great... I was wondering if I can take the HAREC exam online with a ...
0
votes
1
answer
43
views
How do you decide on number of turns for twisted gamma match?
I'm looking at a 40MHz short transmitting loop (STL) with 6 rectangular loops: I need to fit within some design parameters and this gives the good radiation that I need in the near field.
If I want to ...
- 101
0
votes
1
answer
89
views
Why are the signals that my antenna is receiving weak? [closed]
I recently bought the EFHW antenna kit from ARRL, put it together, and set it up. But, my received signals were not clear enough to hear clearly. Is the problem specific to the antenna from ARRL, my ...
- 73
0
votes
1
answer
48
views
Optimal antenna configuration for edge-on power transfer
I need to build a MHz antenna that can power an RFID chip that responds to mag field perpendicular to the plane of a loop antenna, e.g, using STL transmitter with a small receiver loop in same plane ...
- 101
3
votes
1
answer
125
views
How do you make a HF contact?
I asked google, but I had no luck. It didn't say anything about what you should say in a contact. It only said how you should start a contact. Also, I have heard that you are supposed to give a RST ...
- 73
1
vote
0
answers
38
views
Getting My First Radio(Transceiver) [closed]
I'm a prepper based in Pakistan, currently exploring communication options for grid-down scenarios. My recent discovery of ham radio has sparked my interest, both for preparedness and as a hobby. At ...
2
votes
1
answer
90
views
Operation of an off-center fed vertical for 10 meters
I am looking for a smallish omni-directional 10 meter antenna for installation in my attic. I notice that MFJ sells one called MFJ-1790. They call it an off-center fed vertical, and it has two ...
- 23
2
votes
2
answers
51
views
Find the the geographical North for yagi setup
I am setting up a 435MHz cross polarized yagi antenna on Yaesu rotor (for both azimuth and elevation). The application is satellite tracking. The beamwidth of my antenna is 20 deg horizontal and ...
- 29
3
votes
1
answer
60
views
Statistics on ham operators age, internationally
Are there statistics that cover more than the USA regarding how the age of
licensed amateurs
members of national ham organizations
is distributed? All I get are questionable sources on the internet ...
- 15.6k
6
votes
1
answer
990
views
Why not access the AO-91 satellite at night during eclipse?
According to amsat-uk.org, the AO 91 satellite should not be accessed during eclipse because it is near EOL.
AO-91 (RadFxSat / Fox-1B) Near end of life. If you find it on, do not attempt to access in ...
- 723
0
votes
0
answers
71
views
High SWR at full height
I operate a low power FM radio station. I have always had issues with high SWRs. Recently I have purchased a new transmitter, new antenna, and new 100 ft cable from the same company assuming they ...
5
votes
0
answers
85
views
Are there any stations other than W1AW that fall under 47 CFR 97.113(a)(3)(iv)?
47 CFR 97.113(a)(3) normally prohibits amateurs from transmitting
[c]ommunications in which the station licensee or control operator has a pecuniary interest, including communications on behalf of an ...
- 604
0
votes
1
answer
60
views
I get no audio on my new Quansheng uv-5r plus despite green receive light
Quansheng uv-5r plus. First time on these devices, sorry.
The receive light goes on but no receive audio.
Transmit on ht works fine. Audio from device prompts are ok.
Checked frequency traffic with ...
- 29
2
votes
1
answer
81
views
Measuring Power - Attenuators and 50 Ohm Termination
I'm attempting to measure the output power of my transceiver + linear amp combination and I would like to confirm that my measurement approach is correct. I need to get the output power down to a ...
- 989
0
votes
2
answers
94
views
Using Aviation VHF radio on different frequencies
I have an old Icom A-5 aviation handheld with a frequency range of 118.000-136.975 MHz on top of WX, AM, and FM receive functions. Is there any way with little modification, or a simple static build ...
2
votes
1
answer
117
views
Why are there weird sounds in radio?
When I'm tuning through the radio on HF, suddenly, I hear a tone. So, I tune back, and the more I tune back, the more the tone changes pitch. For example, if I tune back 1 kHz, the sound rises by 1 Hz....
- 73
1
vote
2
answers
100
views
Optical line of sight over long distances?
Is there a way to use radio to restrict communication to optical line of site at distances greater than 10 miles?
For example, the signal is transmitted directionally from a mountain top fire lookout, ...
- 113
-4
votes
1
answer
69
views
Getting RSSI values between two B210 USRP to print on a text file [closed]
I have been using Gnuradio for a while and wanted to print the RSSI values to a text file as received from the other USRP. My objective is to print RSSI values from one transmitting USRP to another ...
2
votes
4
answers
163
views
Wave bounce inside a resonant antenna
Let's assume we have a transmitter, a feed line, and a standing wave antenna (dipole, etc.). The transmitter is matched with the feed line, and the feed line is matched with the antenna, which is why ...
- 47
1
vote
1
answer
145
views
When should I switch antenna inputs on the Yaesu FT-897D?
The Yaesu FT-897D has two antenna ports: "HF/50 MHz" and "144/430 MHz". The manual states:
The "HF/50 MHz ANT" jack is used for HF and 50 MHz, while the "144/430 ...
- 1,852
2
votes
1
answer
60
views
What is the apparent AC voltage source caused by a mismatched impedance on the antenna or transmission line?
From Understanding how antenna mismatch can damage a transmitter
"The reflected wave appears to the transmitter's antenna port... as an AC voltage source... whose magnitude and phase depend on ...
- 145
2
votes
2
answers
161
views
Understanding how antenna mismatch can damage a transmitter
I know it's important to tune an antenna to the same impedance as the transmitter for maximum power transfer. But I've read that if you don't do so, you not only get less radiated power, but you can ...
- 145
0
votes
1
answer
95
views
Suggestion for the RF cable
I am setting up a HAM antenna (50 ohm) on my house terrace. The cable length is going to be around 25 meters from terrace to my transmitter. Which type of co-axial RF cable should I choose with low ...
- 29
6
votes
1
answer
1k
views
License problem in Spain
I am from the UK and live in the Canary Islands. I am told I have to take my ham radio license test in Spanish, but I don't speak Spanish. Is there a way around this somehow? Maybe take the UK one (...
3
votes
1
answer
83
views
Impedance of linear loaded 1/4 wave element
I am in the process of planning a multiband vertical antenna and have a few questions I would be grateful for any advice on.
So I plan to have 1/4 wave elements for bands 20-10m with a common ...
- 31
1
vote
1
answer
32
views
nrparms: SIOCADDRT: Inappropriate ioctl for device
I am learning about the Linux amateur radio protocol stack. I'm trying to connect to a remote node using netrom. My axports file looks like:
...
- 598
1
vote
1
answer
65
views
Advice on keyer: two paddle on old Kenwood with 'straight key' only
I am using a Kenwood TS-130S, which has only a 1-pole jack for the key (it is a 1/4" telephone jack, aka "monoaural", tip and barrel only). I know that I need to have an aftermarket ...
- 11
0
votes
0
answers
40
views
How to fix correlator memory allocation error in GNSS SDRLIB while post processing?
I am using GNSS SDRLIB for postprocessing a RTL SDR signal sample and as you can see I was able to get the acquisition of the satellites, however I'm not getting any position fixes (the obs file is ...
- 11
1
vote
1
answer
77
views
Distance between Yagi antennas for 3500 MHz 5G
I have a lowcostmobile Rad5G-Ultra that I've been used for years with my LTE router.
Now I have to use this couple of antennas for 5G through a ZTE MC801a (3500 MHz).
Please, can you tell me the ...
- 11
0
votes
1
answer
36
views
Use Direwolf for ax.25 connections w/o kernel support?
Direwolf includes a complete AX.25 implementation, which it uses internally for various sorts of beaconing, etc. Is it possible to use the Direwolf ax.25 stack to connect to another node without using ...
- 598
3
votes
0
answers
53
views
APRS-IS filter by message sender
I'm using KD0NKS' JS-based APRS-IS demo to query APRS-IS servers directly. I'm trying to only receive messages sent from my callsign using server-side filters.
I've tried using a budlist filter (b/), ...
- 31
0
votes
1
answer
54
views
data rate for dsss in amateur radio
I have a question about the data rate for a DSSS transmission in amateur radio. I give an example with a bandwidth $B=4$ kHz, a spreading factor $SF=64$, a DQPSK modulation and a convolutive code with ...
- 1
2
votes
2
answers
107
views
Long Distance antenna feedline for UHF/2.5GHz signal
I'm building a boat towed underwater platform. This underwater platform has a single board computer with a remote wifi antenna connection via a u.fl connector.
I'm experimenting around with a way to ...
- 123
2
votes
2
answers
76
views
3rd party rules
Why are there 3rd party rules?
http://arrl.org/third-party-operating-agreements lists the countries we are allowed to pass 3rd party messages from.
The fcc regulations specifically state that 3rd ...
- 97
1
vote
0
answers
26
views
Yaesu ADMS-13 software: open saved file without reading config from radio first?
I recently purchased a Yaesu FTM-6000. I like the radio, and I'm happy that the ADMS-13 software runs under WINE without a problem, but the software has some truly odd behavior and I'm wondering if I'...
- 598
1
vote
1
answer
41
views
What's the connecter type adapter to fit Nagoya NA-771G (SMA Male) to Baofeng UV-5R?
I've got an antenna Nagoya NA-771G (SMA Male) what kind of connector adapter do I need to fit for my Baofeng UV-5R
- 111
2
votes
0
answers
66
views
trying to get a passive AM bar antenna to work
I pulled a nice big external AM ferrite bar antenna off a working stereo. 5.5" long.
it has 4 wires coming off of it. red must be the main wire, because checking that with an LCR meter connected ...
- 31
1
vote
1
answer
92
views
trying to make a crystal radio, it doesn't work right
issue: trying to make a crystal radio, doesn't work right
components:
diode pulled from a working crystal radio set
variable air-gap capacitor gang (VC), 125/250/250 pF in parallel, 40-625 pF total
...
- 31
2
votes
1
answer
609
views
Programming cable doesn't recognise Quansheng UV-5R Plus
I am trying to program my Quansheng UV-5R Plus with a Baofeng cable. The cable works on my Baofeng, so I know it is OK. I'm told on the website to treat the UV-5R Plus just like a UV-5R but what I get ...
- 21
0
votes
0
answers
178
views
Can someone please tell me the difference between Quansheng UV-5R, UV-5R (8) and UV-5R Plus?
I cannot find anywhere the difference between these 3 Quansheng radios...UV-5R, UV-5R(8) and UV-5R Plus. I have just purchased a UV-5R Plus...I know it has the AM air band, but I am not sure hyow any ...
- 21
-5
votes
2
answers
82
views
Safety on communications cable that has 220v
As you know there are bias tee adapters that can mix power and radio signals.
Lets say that the power is actually 220v ac. I want to put in front of the bias tee a resistor/fuse that should blow up ...
- 13
2
votes
1
answer
60
views
A passive splitter/combiner in full-duplex mode
We have an RF chain where a full-duplex radio transceiver with Tx and Rx port operating on different frequencies. These are connected to a single antenna (that can Tx and Rx) via a diplexer, so that ...
- 123
1
vote
2
answers
115
views
Does a grounding block on a Yagi antenna with a balun and coax feed have the potential to add signal interference?
I have a commercial UHF/VHF Yagi designed for TV reception, also used for 2 meter reception, that has been installed for years but seems lately there's increasing amounts of signal disruption.
I have ...
- 113
3
votes
1
answer
273
views
Bonding ground rods for lighting protection
I am installing 2 antenna masts on one end of my house. The utility ground is on the far end of the house, and was buried under the asphalt driveway.
Working with my electrician, he suggests 2 ground ...
- 97
1
vote
3
answers
306
views
Is it legal to practice using a one-time pad?
Imagine two people want to practice the procedure for sending and receiving messages over amateur radio that are encrypted using a one-time pad. Here’s what doing this for real would look like:
...
- 11
3
votes
3
answers
225
views
Advice on constructing half wave dipole with reduced velocity factor for site that is not quite big enough?
I want to construct an antenna competent on the 160m band, but I haven't got quite enough space, here's my thinking, please let me know if/what you agree/disagree with.
I have a plot of land with ...
- 215