All Questions
4,507
questions
1
vote
1
answer
18
views
What does R5m mean in an APRS entry for a WinLink gateway?
If you look at an APRS description for a WinLink gateway, you'll see something like "144.950MHz 1200 R5m Winlink Gateway". I know that means it's a 1200 baud packet station serving as a ...
- 248
1
vote
1
answer
42
views
Swapping crystal from HF to VHF in a QRP tranceiver
I am trying to build a short-range QRP weak signal VHF 2m CW transceiver. I found a small circuit that fit my needs, but it was made for use on 40m instead of my target frequency. The circuit included ...
2
votes
2
answers
413
views
Is a boom important to a Yagi?
I am trying to make a yagi for a 900M. The tinkering starts causally with some 1.2mm welding wire (cut to size based on K7MEM yagi calculator, direct soldering, no special matching as suggested on ...
- 121
0
votes
0
answers
18
views
Does anyone know other variations added to bens best bent wire warm up?
I listened to this version of BENS BEST BENT WIRE performed by Bill W9VC with a straight key:
https://youtu.be/LNiG8DPXHFY
and I think I heard
...
- 101
2
votes
2
answers
55
views
Will spray painting a J-pole impede functionality?
I'm building a J-pole antenna like the one specified here: https://www.sysjolt.com/2022/building-a-j-pole
As you can see it's made of copper pipe and I'd like to camouflage the antennae a little bit.
...
- 235
1
vote
1
answer
20
views
Manually program the ISS freqs and tones into uv5r without chirp software
Wondering if the programming data for communication with the iss can be manually programmed in to a baofeng uv5r without using chirp sofrware.
- 11
8
votes
3
answers
2k
views
Why do single band 10 meter radios exist?
I wonder why special radios for 10 meter band are manufactured?
On the one hand - any fully-fledged HF transceiver includes 10 meter band.
On the other hand there are no only "15 meter band" ...
- 91
0
votes
0
answers
21
views
How do i configure fldigi for a UK QTH?
Location configuration in fldigi for Ubuntu only offers 'state' and 'county'. How do i enable it to accept non-US QTH?
- 105
0
votes
0
answers
14
views
Anyone know a repair service for sgc 2020? UK [closed]
My sgc has not been used for some years. Setting it up revealed the following issue: in USB or LSB modes when PTT pressed the power goes to full on, even in silence.
Would expect zero power when ...
- 105
2
votes
1
answer
40
views
Ham Radio Deluxe not importing QSOs from LotW
I have various computers that I use for ham radio and I use Ham Radio Deluxe as my main ham radio app, especially it is my logbook. I'm trying to use LotW as a way of synchronizing my logbook among ...
0
votes
1
answer
53
views
Does the Yaesu FT-897D have a BIOS/firmware in FLASH memory that could get corrupted 15 years in storage? Is there a re-install procedure?
I'm helping my non-ham sister disposition my old Yaesu FT-897D rig that's been in storage for 15 years (couldn't take it with me to Taiwan).
Other hams are looking at it now. While it worked when I ...
- 521
0
votes
1
answer
51
views
Can you use elements of fan inverted V for guying?
Diagrams of fan inverted V antennas usually show the elements quite close together and parallel.
Anyone experience of, or insights about, spacing elements at say 90° or 120° around the tower to guy it?...
- 105
0
votes
0
answers
23
views
More details on the Motorola DP3400 Walkie Talkie's connector and signals?
I've been trawling the internet for more information and specs on the Motorola DP3400 Walkie Talkie's connector and the input/output signals on it. I know for sure from a few sources including this ...
- 101
0
votes
2
answers
41
views
FSK: Selecting center frequencies and Carson's Rule
I'm implementing 2FSK and 4FSK modulation schemes for an experimental system. I'm using GNURadio, although that shouldn't affect the question.
I'm trying to figure out how the center frequency should ...
- 133
1
vote
1
answer
69
views
Zero resistance inductor
I have RF schematic and there is one inductor with no inductance value, but with this.
Where and how I can buy this inductance? I searched an can't find inductance with 0ohm and 1%. What 1 % does ...
- 131
0
votes
0
answers
32
views
How to use GNU Radio to demonstrate FM demodulation without baseband signals
Using GNU Radio, I'm currently trying to create a flow graph containing a simple demonstration of how FM modulation and demodulation works. Since the target audience is not accustomed with complex ...
- 101
0
votes
1
answer
43
views
Utilising old CB Base Antena to 5g Antena
Is it possible to utilize an old CB Base Antenna (10 meters tall) as 5g Antenna to plug into the back of a 5g router that is currently only registering 4G? I have one on top of a single story unit ...
2
votes
1
answer
60
views
UnUn for VHF and UHF
Is it possible to build an UnUn for VHF or UHF like in HF?
Goal is to use a simple endfed wire or piece of metal as an antenna.
EDIT: I meant "endfed halfwave".
- 21
2
votes
1
answer
81
views
Antenna from the roof / coax cable to Ham and Weather radios
Just want to make sure I don't need anything else (to prevent damage to the radios)
I have an antenna on my roof. It used to be used for TV but I switched back to cable.
Can I literally just use a ...
- 21
1
vote
1
answer
83
views
Does Velocity Factor pose a significant cable loss?
We know that a lower Velocity Factor translates to using shorter runs of cable in resonant circuits. That apparently means that there is resistance to the flow of electrons, slowing them down.
So ...
- 413
1
vote
0
answers
46
views
In the TXQ G63 (aka MyDEL G63), what are Compander, Scramble, Frequency hop, SPEC, SPEC Code and Scan Add?
This is the software use to program the TXQ G63:
I think I have a guess about Compander and Scramble, but I'm totally lost when it comes to Frequency hop, SPEC, SPEC Code and Scand Add.
Do you know ...
2
votes
1
answer
82
views
How do these ceiling mount dome antennas work? Are these discone antennas or horn antennas?
The small cone is connected to the larger one. The coax center cable is terminated into the small cone and the coax shield into the larger outer cone.
The screenshots are from this video https://www....
- 21
1
vote
1
answer
53
views
ARRL numbered text ARL65 (ARL SIXTY FIVE) - what do the gaps stand for?
I am trying to understand ARRL numbered text messages and this one is not clear to me:
ARL SIXTY FIVE: Arriving _______ on _______. Please arrange to meet me
there.
The second gap seems to be ...
0
votes
1
answer
28
views
Alinco DJ-VX50 programming interface
I would like to avoid buying overpriced ERW-7 programming cable. I tried several USB/serial interfaces following instructions from other users, e.g. https://www.youtube.com/watch?v=LQT3d-_-kdU
There ...
2
votes
3
answers
135
views
Loss of information and aliasing in superheterodyne receivers
For a radio / SDR that downshifts a signal to an IF / intermediate frequency band, wouldn't information be lost in the case that the original signal is above the IF sampling rate? For example, the ...
3
votes
1
answer
172
views
Connection for Moxon antenna (blank space)
I just printed a Moxon Antenna and want to wire it. The Antenna wiring has a blank space and I'm not sure how to wire this place. From picture bellow I got that I need to connect a coax shield to top'...
0
votes
2
answers
68
views
Exposure to AN/FRD
Why are Wullenweber CDAAs obsolete?
My dad worked inside the FRD sites on various Navy duty stations and is suffering now from Parkinson's and dementia. Has anyone else heard or read of similar side ...
- 1
4
votes
2
answers
109
views
How can an HT antenna be half wave?
There's a model of HT antenna for the GMRS band by Nagoya (NA-771G) that's specified as a half wave. How can that be? An end fed half wave antenna needs a 49:1 impedance transformer to match with ...
- 781
1
vote
1
answer
66
views
Noise power with and without antenna
I have designed a receiver at 440 MHz with a 10 MHz signal bandwidth. I have measured the sensitivity of the receiver in a cabled setup (coax cable between transmit and receive) and that is about -93 ...
- 11
2
votes
1
answer
89
views
What this E(EL) symbol does mean?
I can't understand what this E(or EL) symbol does mean. I know that Zo means impedance and I can calculate trace width according it, but what E symbol does mean?
- 131
1
vote
3
answers
104
views
Why does SWR of a dipole decrease the closer it is to the ground?
I experimented with a 20m dipole made of a 1:1 balun connected to 2x ~5-meter lengths of copper wire, running parallel to the ground (by "ground" I mean "pavement", not quite the ...
- 15
0
votes
2
answers
51
views
Why does Tone Spacing decrease with increasing T/R Periods in WSJT-X modes?
In various weak signal modes of WSJT-X, the Tone Spacing decreases with increasing T/R Periods. For instance for FST4 / FST4W (as decribed on page 1 of the Quick-Start Guide) we see:
T/R period (s)
...
- 15
3
votes
2
answers
529
views
How to establish RF ground for 1/4 wave vertical in apt on 3rd floor (about 35ft above the ground)
I am struggling to understand how to introduce an MFJ-931 artificial RF ground into my current system and am hoping for some help to sort out best practices. Although my use-case seems pretty common, ...
- 173
1
vote
3
answers
79
views
Tips for getting a 2m dipole higher while out in the field
I want to start operating the 2m band while camping, but with my current setup, my antenna would be very close to the ground and ineffective. So I'm wondering, does anyone have tips for constructing ...
0
votes
1
answer
80
views
Is 100m too long for hf feed wire?
I have room to erect a DX Commander, multi-band vertical, and to give it a good number of radials on a good clear site.
Problem is I would need to run about 80 - 100m of coax feed from operating ...
- 105
5
votes
1
answer
93
views
Why does my received power rise so much when I connect an antenna?
I am in early stages of making a narrow-band radio receiver (block diagram below). To give you an idea, I am using a simple CP-FSK based modulation scheme, and have achieved 5dB SNR with a Tx signal ...
- 153
5
votes
1
answer
127
views
What is this vertical antenna with radials pointing up
I work next to "Koninklijk Marine Kadettenkorps Afdeling Oostende" (Royal Marine Cadet Corps Ostend). They have an antenna that I've been wondering about for years now:
It is a vertical ...
-3
votes
1
answer
154
views
unstable frequency generator using gnuradio 3.10
I run gnuradio on windows 11 using anaconda install. It uses hackrf without portapack. I am using signal amp from a F16 fighter jet.it requires 10dbm input and runs on 24v 2amp. https://imgur.com/...
- 1
2
votes
2
answers
91
views
HF vertical 1/4w antenna on a tin roof?
I would like to build a 1/4 ~ vertical antenna on my tin roof for a ground plane.
Does the angle of the roof matter?
Should the antenna be vertical, or perpendicular to the roof?
Would it be better ...
- 23
2
votes
1
answer
88
views
Connect mobile device with coax cable to SDR board
My goal is to connect mobile devices using a coax cable with a SDR board to be independent from using the air interface and antennas. I don't know how to connect my devices with the SDRs since I'm an ...
- 123
1
vote
2
answers
95
views
Off-center fed long wire antenna
I want to feed a horizontal wire antenna (approximately 150' long at 50' or more above the ground) for multi-band HF operation with an off-center (25-33%) feedline. The element wire will have no ...
- 41
2
votes
2
answers
95
views
Is the noisy spectrum from 20MHz to 330 MHz normal?
I have recently been testing some VHF/UHF antennas for reception in my Lab, and have noted something I could not explain. Following are the spectrum plots captured on our R&S FSV spectrum analyzer,...
- 23
1
vote
2
answers
114
views
Is there a proper way to connect multiple radios via coaxial cable so they can be tested without going over the air?
Let me state up front that I am not an RF engineer, but I do have a EE background.
I'm working with a group that has a collection of radios, VHF and UHF (military) that is licensed to use a VHF and ...
0
votes
2
answers
101
views
Would a 3D-printed antenna case interfere with the antenna itself?
I primarily use a Baofeng for most of my contacts. I've got a pretty good antenna (14.5 inch whip), but when I have to pack it into any sort of bag, I'm always worried that it'll get bent. This has ...
- 125
2
votes
1
answer
75
views
Is morse proficiency required for UK ham license?
I am an Extra Class license holder who has just moved to Scotland. I am working through online training to obtain my license for here. I’m curious if Morse proficiency is a requirement for licenses ...
- 21
7
votes
1
answer
83
views
Is it possible to remove the previous callsign information?
I had a name change some years ago and had a new callsign generated. But the FCC keeping a record of my previous callsign puts me at risk of an abusive ex finding me.
Is it possible to disassociate ...
- 171
0
votes
0
answers
14
views
I have suddenly lost the ability to transmit CW on M IC-7200 xnxceiver. I am able to receive sigs but keyer does not work.makes dits but no dahs
My trusty IC-7200 has worked flawlessly for over 15 years but now I can't transit CW which is the only mode I work. I think something in the set for paddle connection is wrong.
The directions in my ...
1
vote
2
answers
97
views
Can we connect 13.5V power suppy for 13.8V Ham Radio (YAESU FTM-300DR)?
I have HAM base station equipment (YAESU FTM-300DR) and Power Supply (Axiom BM 101B). HAM equipment needs 13.8V. But the power supply is 13.5V - 15A.
Please advise, is it safe and fine to connect this ...
1
vote
1
answer
59
views
How to splice a 12 gauge, stranded wire to a ladder-line stranded wire?
I am building a zs6bkw dipole using a ladder-lock. For mechanical strength, I am looping the 12 gauge wire, as in the image below, and swaging it. The next step is to join the thick antenna wire to ...
- 173
2
votes
1
answer
57
views
Can I use 14/2 UF-B wire as transmission line?
I'm wanting to build an antenna system utilizing twin lead feedline running to an 80 meter doublet. I'd like to avoid the typical hassles that accompany 450 or 600 ohm ladder line so I'm considering ...
- 23