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Resonant 80m End Fed Halfwave Antenna With Counterpoise - Questions

Originally, I built an 80m EFHW, 130.5 feet long cut for approximately 3.58Mhz. I attached a 49:1 UnUn at the feed point 13 feet above the ground with coax back to the shack. I did not use a ...
Ron K5TDF's user avatar
-1 votes
0 answers
15 views

Can't submit cabrillo log to YUDX: Wrong date in log

When submitting to http://hamcontest.rs/HF-Robot/index-HF.jsp the site says: GREŠKA! Greška u datumima rađenih veza / Wrong date in log This is the logfile: ...
Romeo Kienzler's user avatar
0 votes
2 answers
71 views

What is this pulsating signal?

When scanning through UHF, I find that there are a few frequencies that made a sound similar to a fast drum (~300 bpm?) Here are a list of the frequencies: 451.200 MHz 454.280 MHz more coming soon ...
o'o's user avatar
  • 119
0 votes
0 answers
38 views

Use of filters for weak SSB when there is no QRM

On bands like 10m when there is often little or no QRM (just gaussian noise), are the "Noise Reduction" filters intended to make weak phone signals more understandable? My subjective view is ...
gschro's user avatar
  • 157
0 votes
1 answer
59 views

Converting a 470-694Mhz TV antenna for 433Mhz reception

I'm working on a project which requires me to pick up LoRa signals that will be transmitted from a relatively low gain antenna. I've figured out that a large dipole would be idea for the receiver ...
Hristos's user avatar
3 votes
1 answer
106 views

Max voltage on antenna pin of Si4732?

I'd like to drive the antenna pin(s) of an Si4732 receiver chip with a device that isn't an antenna. I don't know what voltage to scale to, though, and don't want to fry the chip. The datasheet (or, ...
Erhannis's user avatar
  • 133
1 vote
1 answer
44 views

Printing the Signal Power on the terminal from the USRP source block on GNURadio

I'm working on a project that makes use of the Ettus USRP X300 and the GNURadio environment. I have established a connection between the transmitter and the receiver of the USRP and I'm able to read ...
Abhiram Prakash Alamuri's user avatar
1 vote
3 answers
116 views

Receiving -80 dBm on HF

When using my EFHW antenna, I saw that it was -80dBm to -90dBm. So, I can barely make out anything they are saying. I read that you are supposed to have the antenna running north to south, and the ...
o'o's user avatar
  • 119
-1 votes
1 answer
90 views

Why can I connect simplex at 146.52 but not at 145.200 and 147.000? [closed]

I am preparing myself to use Winlink. I am preparing myself to use VARA FM. 145.000 is the Simplex frequency used by our local university (Montana State). It can be used for both voice and digital, ...
Carol Flaherty's user avatar
1 vote
4 answers
90 views

What core material would offer the highest sensitivity in the design of an ELF/VLF handheld rod antenna?

I want to design an ELF/VLF handheld rod antenna. What rod material would offer the highest sensitivity at these low, low frequencies? Below 50 Hz.
Ron K5TDF's user avatar
-2 votes
0 answers
91 views

Can I find audio recordings of a past radio operator?

I don’t know anything about ham radio but I am trying to find audio recordings of my grandpa who used to be radio operator just to hear his voice. I know his call sign but other than that I’m lost. ...
Bono's user avatar
  • 15
0 votes
1 answer
40 views

Help implementing a custom signal source in GNURadio for FMCW

I am trying to implement a custom signal source for FMCW in GNU Radio, but I am stuck. The idea is to generate a CW chirp signal using the formula $ \text{chirp} = \exp\left(1j \cdot 2 \pi \left(f_0 \...
Raj Patil's user avatar
3 votes
1 answer
70 views

Help implementing FT8 crc check in Rust

I'm playing around with implementing portions of the FT8 protocol in Rust. I'm having trouble with the CRC algorithm. Here is my not yet working attempt: https://gist.github.com/JohnRudolfLewis/...
JohnRudolfLewis's user avatar
4 votes
1 answer
83 views

How to properly simulate a crystal filter being pulled?

After reading k1zmt's answer to the question of how to change the resonant frequency of a quartz, I wondered how to simulate a quartz filter to check that result. I went with the following model of a ...
Marcus Müller's user avatar
3 votes
2 answers
124 views

Shifting Frequency of a VHF Crystal?

I have a boatload of 165.550 MHz Regency 10.7 MHz IF Crystals. I need them to resonate for 165.500 MHz. How can I shift the crystal frequency down 50 KHz without opening the 'tincan' and messing ...
Station51's user avatar
0 votes
3 answers
96 views

generic antenna tuner term: impedance matching vs real tuner

Generally, an antenna tuner is nothing more than an impedance matcher. Badly termed, as it does not tunes any antenna. For loop antennas though this is not the case. The antenna tuner does not do any ...
kellogs's user avatar
  • 203
-4 votes
2 answers
103 views

The idea that a non resonant antenna cannot accept current as well as a resonant antenna is a myth?

In a youtube video titled "Antenna Engineer Vs Ham Radio Myths! True or False?" the guy says this in the comments: The idea that a non resonant antenna cannot accept current as well as a ...
K3ZD's user avatar
  • 1
3 votes
1 answer
51 views

Why does RFI demodulate to a buzz sound?

For RFI problems with audio equipment, why does a dead carrier often demodulate to the familiar mains 60 Hz buzz sound? This occurs on multiple audio equipment around the house. There are lots of ...
multicode's user avatar
0 votes
2 answers
59 views

Minmum spacing between two receive-only omidirectional antennas

I need to mount a VHF receive-only omni (166Mhz to be specific) and a UHF receive-only omni (434Mhz) on a pole and plan to use a T-bracket at the top to space the two antennas apart. How much distance ...
TvE's user avatar
  • 101
0 votes
0 answers
27 views

I want to hook up a couple active speakers to my icom 9100 so I have a good range and good volume . the output on the receiver is 8ohms

Can I just plug a 4 ohm powered speaker set into the output of the 9100's speaker output, or will that damage the Icom's amp?
KZ2K's user avatar
  • 1
0 votes
2 answers
69 views

How is the length of an inverted V affected by being too close to the ground?

In the near future, I'm planning to build an indoor inverted V dipole. However, I won't be able to raise the ends significantly above the floor. I understand that this will adversely affect ...
Someone's user avatar
  • 604
0 votes
3 answers
79 views

QRP operation SOTA, what coax cable feed-line for HF?

I've done outdoor activities, POTA and WWFF, with a coax RG58 feed line with PL conectors, around 3 meters (9.8 feets), for wire EFHW antennas working HF bands (40m, 20m and 10m). Now I want to do ...
Trimax's user avatar
  • 103
1 vote
0 answers
71 views

Repeater PTT time

I have made some repeaters with GM300 radios, Using a cable TX-RX to join both radios by the 16 pin. Done it some years ago. But can't remember how I did to make the repeater stand up for a second ...
Elmanoduarte 's user avatar
3 votes
2 answers
118 views

Can I run my antenna coax near a gas line?

I just moved to a new place and would like to put an antenna up in the attic. My shack location is in the basement with the furnace and water heater. In my explorations, I've discovered that there is ...
byl's user avatar
  • 131
2 votes
0 answers
63 views

how to avoid overflow using a python block in GNUradio

I am implementing this code in an embedded python block in GNU Radio to received a stream of bits and extract a part of that stream, but I get "OsOOsOOsOOsOO" in the console and the CPU ...
ANDRES FELIPE RODRIGUEZ RENDON's user avatar
1 vote
1 answer
119 views

Sometimes my Baofeng UV-5R's display turns red spontaneously

Sometimes my Baofeng UV-5R's display will turn red for no apparent reason. I don't know what else to call this so I'll just say phenomena. I have made sure the antenna is properly connected, and when ...
Bro nothing works anymore's user avatar
0 votes
1 answer
38 views

Lumped Solution for Impedance Matching vs. Ferrite Transformer

Using a high-Q LC circuit to match impedance is more efficient than a ferrite transformer, however it is very narrow banded compared to a ferrite transformer. The statement above is...?
Louis Seaman's user avatar
2 votes
2 answers
100 views

How do I ground my first HF rig?

I want to preface this question saying that I am very new to HF and just got my general license. I have only operated using 2m/70cm handhelds and am completely unfamiliar with antenna setup. I ...
Sprock3t's user avatar
1 vote
1 answer
62 views

Testing a magnet mount base antenna

My Comet M-24J 144/440 antenna doesn't seems to receive signals as well as it should. I seem to receive more transmissions on HT radios than the mag mount and micro mobile radio. I only have a Rig ...
Radio Rails's user avatar
0 votes
1 answer
45 views

Radials with centre-loading coil

Does a centre-loaded HF antenna need radials? If I put a loading coil 1,5-2m (5-6,5 feet) high, do I need to put radials out on the ground? Feed point would still be near the ground.
S54KZ's user avatar
  • 1
2 votes
1 answer
65 views

Identify filter on schematic

I am analyzing the Baofeng UV5R schematic. And trying to identify which filter was used in input UHF/VHF RF stage on RDA1846. It seems to me that it is a 3rd order Butterworth bandpass filter. But i ...
Adi Deljanin's user avatar
0 votes
1 answer
89 views

RF Coax Termination Question

I am looking to terminate a line with the below characteristics and having a hard time locating an RF coax terminator. Can anyone help? I have an FPGA HW that is feeding multiple receivers. The input ...
Newb's user avatar
  • 3
8 votes
3 answers
2k views

Can larger antennas damage an HT radio?

Can adapting a larger antenna such as a Diamond X-50 or larger mag mount damage an HT radio? Would it overload the receiver?
Radio Rails's user avatar
8 votes
1 answer
964 views

How restricted is the eastern edge of the National Radio Quiet Zone?

In several years we may be moving to just west of Charlottesville, VA (North Garden to be specific). It looks like that is just barely west of the eastern edge of the National Radio Quiet Zone and so ...
QuantumMechanic's user avatar
0 votes
1 answer
77 views

How To Convert Morse Key Input To Audio

I am thinking of purchasing a TYT TH-9800 Plus. Its only drawback is there is no input for a CW device. What Equipment would be required to convert CW output into audio input?
octopusgrabbus's user avatar
2 votes
1 answer
61 views

How can i convert a modulated DSB-SC signal to a SSB-SC signal?

I am designing a simple transmitter using an SI5351A to generate the carrier, then modulating it with a diode ring modulator to generate a dsb-sc signal, then somehow converting it to ssb modulated ...
I_like_python's user avatar
0 votes
2 answers
97 views

Theoretical solution to ham radio repeater range extension for personal use

So here's the theory, I build a personal repeater to access a nearby repeater. In turn it sends a signal to my desired repeater (within range of my repeater) I then build a second repeater to receive ...
Gregory Chapel's user avatar
1 vote
0 answers
58 views

TYT TH-350 unlocking to receive 160-161 MHz in the USA

Recently purchased the TYT TH-350 because it is triband. My version allows for TX/RX 144-148/222-225/420-450. Every other HT I own allows for extended receive only. The TH-350 has a European version ...
Radio Rails's user avatar
2 votes
1 answer
47 views

Can missing QSOs in my contest log adversely affect other operator's scores?

I worked a little of the NA RTTY QSO Party and messed up logging for the first couple QSOs. I have the callsign and exchange data, but can only guess at time and band. My question is whether missing ...
gschro's user avatar
  • 157
1 vote
1 answer
73 views

FCC rule stating emission type for various bands

The general question is as follows: Where within the FCC rules exactly (47 CFR 97.xxx or similar) does it specify the emissions type (ie. CW, Data, RTTY, Phone, etc...) allowed for a specific band for ...
John's user avatar
  • 23
4 votes
2 answers
122 views

Why is SNR for FT8 defined using the noise power in the 2500 Hz channel containing the FT8 signal?

I see the term "SNR_2500" is often use to make it clear. Is it useful to use this SNR definition in some contexts? Is this kind of convention used in other digital modes or communication ...
gschro's user avatar
  • 157
0 votes
1 answer
118 views

Input impedance of a shortened dipole antenna

I want to make myself a antenna for 40m and 20m wavelength band, but i don't have enough space for a full scale dipole, and even for more compact configurations like delta-loop or inverted v, so i ...
ZecosMAX's user avatar
  • 109
5 votes
2 answers
663 views

What is this (dangerous) connector type that looks like SMA?

At a hamfest, I recently bought a few RF adapters that I thought were BNC to SMA: However, when I tried to use one, it ended up destroying the SMA male plug on the cable I attached to it. It pushed ...
user3486184's user avatar
  • 1,902
6 votes
1 answer
275 views

Why do 9:1 ununs use type 2 material for the core?

I do not understand how a 9:1 unun wound on a T200-2 works. I understand the transformer voltage and current ratios. I have wound several toroid chokes and 49:1 ununs and know how they work. What is ...
Dereck's user avatar
  • 484
3 votes
2 answers
135 views

G/ in front of a QSL calls sign: SV1ABA

I am indexing my father's QSL call sign cards. I came across a QSL card sign SV1ABA. It starts with a G/. What does the ...
Dr. Anastasia S. Weigle's user avatar
3 votes
1 answer
45 views

Rig Expert AA-35 ZOOM Amateur Band coverage in the United States

I am having difficulty understanding the low end of the AA-35 ZOOM frequency range. The tool can help with frequencies between 35 and .06 MHz. Looking at a chart I saw that 60 kHz was Standard ...
Radio Rails's user avatar
2 votes
1 answer
54 views

Use of Yaesu FT-7800R External Speaker Jack Loss of Audio

I plugged an external speaker into our Yaesu FT-7800R EXT SP jack. As a result, I've lost audio, both when the speaker is plugged in and not plugged in. A ham told me that the FT-7800R has a known ...
octopusgrabbus's user avatar
1 vote
0 answers
40 views

What should I put in the CLAIMED-SCORE field in my CQ WPX RTTY log?

I have dabbled in contests mainly to collect states and entities, and have occasionally sent in check logs. I just worked the CQ WPX RTTY contest, and would like to submit my logs for credit but the ...
gschro's user avatar
  • 157
1 vote
1 answer
49 views

Where to find definition of ITU ZOnes / CIRAF zones

Writing Android logbook. Still in search for ITU zones map. Best option would be GeoJSON with list of Polygons (one per zone) Second best any list of zone border points for each zone. Any help ...
Kuba SP5NZF's user avatar
-3 votes
1 answer
246 views

Handheld amateur radio

Recently purchased a MY-EMR1 which is a handheld ham radio and I want to synchronize it to my sisters in another state if it is possible, she has the same type of radio. All the frequencies have been ...
cookie1's user avatar

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