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votes
1answer
24 views

How does this W6NBC “derivative of the classical slot antenna” work?

Via the https://ham.stackexchange.com/a/9883/1362 answer regarding a slot antenna for a 2m mobile application, I was introduced to this (pdf) interesting antenna design: The designer John Portune (...
1
vote
0answers
20 views

Baofeng UV-9 Info and Help Please!

I have scoured the internet for info on this radio. Specs, programming, manuals, to be exact, yet I can find NOTHING other than sellers of the radio. Anyone have any links they'd be able to share! I ...
1
vote
3answers
299 views

How to increase the bandwidth of half-wave dipole antenna?

I have designed a half-wave dipole antenna for frequency range of 150 to 200 MHz. Due to resonant frequency of 175 MHz, Its dimensions are: L=817.44 mm, R=1.71 mm. Impedance is also equal to 73 ohms. ...
2
votes
4answers
66 views

Does 3 W vs 5 W TX power make a huge difference in QRP CW operation?

I've bought the QCX+ 40 m band radio. I will be powering this off a 12 V battery. I read on the manual the RF power at 12 V is just 3 W whereas on 15 V it is 5 W. Should I buy a boost converter for ...
1
vote
1answer
46 views

How do you open ax.25 ports?

I'm trying to follow this tutorial I almost got to the end, about 9:15 was where I got stuck. Right about there, the speaker is about to wrap up- but I get a couple error messages. ...
2
votes
1answer
73 views

For the FT-60R, does the NC-88B power supply work with the YAESU SBH-13 charging cradle?

I bought a Yaesu FT-60R years ago. Instead of coming with a charging cradle, it came only with the NC-88B power supply. The NC-88B power supply isn't very intelligent--I don't believe it stops ...
3
votes
1answer
54 views

Talk Around vs Reverse

I thought that "Talk Around" and "Reverse" were two ways of referring to the same thing: swapping a channel's transmit and receive frequencies so that one could e.g. listen for ...
1
vote
1answer
72 views

Hunting RFI with bars every 61 khz

I realise there have been many great posts on hunting RFI, i've got pretty close to tracking mine down, but would appreciate some insights from the ham.se experts :) I've done quite a lot of work to ...
0
votes
1answer
65 views

Yagi performing far worse than a dipole

A few months ago, I built a 6 element yagi: 3 driven elements, and 3 reflectors. For 10-15-20m. I was able to tune it to SWR 1:1 for the FT8 frequencies in each band. This antenna is only 6m above ...
4
votes
1answer
59 views

How to track down and neutralize this apparent mixer creating noisy emissions around my signal?

When I transmit, it there seems to be something mixing and reflecting my signal. For example, when I transmit on 14.300 MHz, I see signals above my transmitted signal at at 14.500, 14.700, 14.900, etc....
0
votes
0answers
31 views

three-band vhf/uhf ground plane antenna [closed]

I recently saw a ground plane antenna on a mast with four radials drooped at 45 degrees and in its center instead of one vertical element there were three different length verticals mounted within an ...
0
votes
0answers
66 views

what frequencies is this antenna cut for?

I just bought a magnet-mount whip antenna at a garage sale. It has no brand markings anywhere on it. it is 32" long overall but is broken up into three segments by what appear to be two small ...
0
votes
1answer
65 views

How does PTT from one two-way radio prevent input on another?

I'm very much a beginner with radio. I have a simple set of Baofeng BF-888S radios, and in my basic use with those, I got very curious about something: when you push the PTT button on one radio to ...
0
votes
2answers
37 views

Where can I find a table listing the maximum PEP per band?

I'm building myself an Excel Cheat Sheet.
4
votes
2answers
209 views

Does the output of a BFO for a short wave receiver have to be exactly a sine wave?

I want to build an external beat frequency oscillator (BFO) for an old valve Eddystone receiver I have. There are many circuits for BFOs on the internet, they are mostly similar, the idea seems simple ...
2
votes
1answer
40 views

Resources and guidance regarding APRS

I know getting my Technician License is the place to start, however, I have in my head a clear path that I want to achieve and am looking for guidance for the most efficient way to achieve that goal. ...
4
votes
2answers
103 views

How do I know if my coax connectors are good?

In installed a couple of compression style PL-259 connectors to the ends of RG8/U FOAM coax. It's about 16 feet in length. Here is an example of one of the connectors: How do I know if the coax is &...
1
vote
0answers
16 views

how to set the CFO standard deviation in CFO models

I need some help with a simple thing. I am trying to simulate carrier frequency offset model for Bluetooth Low Energy standard in GNURadio (I am bit new to this). For this purpose, there is a CFO ...
2
votes
1answer
63 views

What is an Audio Peaking Filter?

What is an Audio Peaking Filter? And how might that be different from an ordinary (narrow) CW bandpass filter, or from tunable audio filters (with fully configurable upper and lower cutoffs)? Does a ...
0
votes
2answers
95 views

Which cable is better for ham radio antenna? RG58, RG59, or RG6? [closed]

Which cable is better for ham radio antenna? RG 58, RG 59, or RG 6? Based on [1], RG6 has lower signal loss. So, is RG 6 a better cable? Or there are no differences? [1] https://sewelldirect.com/blogs/...
5
votes
0answers
77 views

How to estimate input and output impedance of an amplifier?

I'm trying to figure out how to design power amplifiers which input and output are properly matched to 50 Ohm. My thinking was that the most bullet proofed approach would be to model an amplifier in ...
5
votes
2answers
169 views

What are these antennas?

On a recent trip to China I photographed a number of "antennas" that I do not recognize. Are they even antennas?
4
votes
3answers
77 views

What is the difference between RIT and XIT?

What is the difference between RIT and XIT? When would one use one and not the other for split (or other) HF operation? When would one need both? Which one is more useful for a transceiver to have ...
0
votes
0answers
42 views

Omni 144 MHz antenna

I plan to build omni antenna. My goal all about better gain versus a 1/4 wave antenna. I am curious about radial position of the legendary ARX2B Ringo Ranger. Why is the position in below feed point? ...
3
votes
4answers
316 views

What is the use of dual VFOs?

What is the value of more than one VFO in an HF transceiver? Many novice rigs only have a single crystal oscillator, and a vast number of famous classic transceivers, HF kits, and QRP rigs only have a ...
1
vote
2answers
73 views

Does Improving Earth Conductivity Near a Buried Ground Rod Improve Antenna System Performance?

The suggestion has been made on various ham-related websites that improving the conductivity of the Earth around a ground rod produces a worthwhile improvement in the e-m radiation from a vertical ...
0
votes
0answers
88 views

Built a 2 meter 5 element Yagi

Straight dipoles. I can't get the Yagi to tune. I have tried the 4:1 Balun method with coax but not able to tune. With the straight unbalanced input to the dipole I get a 1:1 swr on about 129 MHz ...
2
votes
1answer
51 views

String in APRS report

Here are two messages I received: ...
3
votes
0answers
81 views

DIY Triplexer for HF (low), 6m (med), and 2m/440 (high)

I'm looking at picking up the TYT TH-9800, which is a Quad-Band FM radio on 10m/6m/2m and 440 (I'm lucky enough to have some 6m and 10m repeaters in the area). I know there exists quad band antennas ...
1
vote
0answers
41 views

How to use OFDM Synch in GNU Radio?

I am transmitting OFDM 16-QAM x 6 carriers packets using the python library amodem and a HackRF. My setup is very simple for the transmission side, it takes the .wav generated by amodem from data and ...
3
votes
2answers
126 views

If the data port on a Yaesu FT-7800R only communicates FM signals, why does the manual mention the port having a bit rate?

I was wondering how the Radio interfaced with a TNC. I thought the computer sent digital data (in a serial format) to the data port on the radio, but from what I read online, it is not a data port. ...
2
votes
2answers
120 views

What nations still require Morse code testing for Amateur radio license?

Going a bit further I'll ask, for which licenses (all or just for licenses for HF operation) and at what speed (5 WPM, 10 WPM, none specified)? The reason I ask is because every so often I'll see ...
0
votes
1answer
44 views

Pondering variations on the vertical bazooka antenna

I've seen these antennas built out of coax that are called a bazooka vertical. It's a kind of 1/4 wave vertical, or perhaps a 1/2 wave dipole. Constructing such an antenna is to roll back the outer ...
0
votes
4answers
101 views

Why are many ground radials preferable to a single ground stake buried 1m deep?

Surely a 1m copper stake provides better ground connectivity for a vertical dipole?
4
votes
4answers
124 views

50Ohm Coax presents 50 Ohms of impedance on which frequency?

Either there's a simple answer that I'm not finding in a spec sheet somewhere, or, I'm asking the wrong question!
1
vote
0answers
69 views

Frequency synchronization in GNU Radio for OFDM 16-QAM x 6

I am transmitting a 16khz data signal using OFDM 16-QAM x 6 carriers and the library amodem using a HackRF. However, I am having issues receiving this signal as the frequency the HackRF transmits on ...
0
votes
2answers
46 views

What is “allied mode” with regards to PSK31?

Wikipedia says: Colloquial usage of the term 'PSK31' in amateur radio usually implies the use of the most commonly used variant of PSK31: binary phase shift keying (BPSK). BPSK uses no error control, ...
4
votes
0answers
63 views

4NEC2 radials & grounds

Teaching myself 4NEC2 and have most of it under control, which is good. Regarding radials & grounds, i've been learning the "rules" NEC(2) has, summarised below. 4.1. Free space. In the ...
2
votes
1answer
72 views

Questions about effective isotropic sensitivity(EIS)

Recently, I read something about EIS (effective isotropic sensitivity) and TIS (total isotropic sensitivity). I'm trying to understand the concept, but I find it's quite hard for me. In the book ...
2
votes
1answer
80 views

How to select capacitor for diplexer use

Follow-up on this question: How to prevent cracking the capacitors in my diplexer? Short story: 2m/70cm diplexer, to be used up to 50W. Schematic from Elsie: S21/S11: I don't know exactly what to ...
1
vote
1answer
64 views

How Does the Propagation of H-pol E-M Fields Compare to That of V-pol E-M Fields (other things equal)?

A rather popular belief on this topic is that h-pol is superior to v-pol. Probably that is traceable to published "far-field" patterns over a lossy ground plane generated by Method of ...
5
votes
2answers
108 views

Can the parallel capacitance of a quartz crystal be directly measured?

A quartz crystal is often represented by this equivalent schematic: simulate this circuit – Schematic created using CircuitLab How to measure quartz crystal motional parameters using a VNA? ...
0
votes
2answers
117 views

Why can I hear Morse when not in CW mode?

I don't "get" CW. I can't understand the chatter on an FM radio broadcast when my radio is set to AM. This makes sense, the signal is modulated using frequency modulation and I am trying to ...
1
vote
1answer
68 views

440MHz collinear dipole array - suitable coax?

friends! Finally found my next antenna project..a collinear dipole array for the 70cm US ham band. The general idea: (image courtesy https://link.springer.com/referenceworkentry/10.1007%2F978-981-...
0
votes
2answers
99 views

Why does the HamQSL website say the 40m band is fair and the 20m band is poor during the day?

http://www.hamqsl.com/solar.html Why is 40m shown as "fair" while 20m is "poor" during the day. Shouldn't 7 MHz be getting absorbed by the D-layer more than 14 MHz?
2
votes
1answer
83 views

What Are the Properties of 43' Vertical Monopoles Used as Multiband Radiators?

43' vertical monopoles sometimes are used with an auto-tuner at their input as radiators in the ham bands from 40m through 10m, but are any performance compromises required to do that?
1
vote
1answer
33 views

What is the maximum antenna cable length allowed in GNSS application?

I am beginner in designing GNSS receiver design and facing concern while testing the high precision GNSS survey.I am using GNSS survey grade antenna for my GNSS receiver application testing, the ...
0
votes
1answer
38 views

Effective area of a phased array

For a $N$-element planar phased array, all the elements are same isotropic antennas. Then, what is the effective area of this array? Is it $$A_e=\frac{\lambda^2}{4\pi}GN$$ where $G$ is the directivity ...
3
votes
5answers
550 views

Do chokes at the antenna feedpoint stop the coax from receiving signals as well, or just transmitting?

It seems common knowledge that a choke at the antenna feedpoint stops the outside of the coax shield from radiating when transmitting into the antenna. But what about stopping the outside of the coax ...
3
votes
1answer
102 views

Ground-Plane radial sizing, is there such thing as too long?

I'm just trying to make sure I understand the theory correctly. I have some triband VHF/UHF/800MHz antennas, I need to mount on a tower so I plan on using a "mobile to base" conversion kit. ...

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