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732 views

VHF / UHF - Terrestrial Circular Polarized Antenna

I've been doing mostly HF for the last 20 years and just recently installed a 2m/70cm mobile rig in my shack for base station work. I like to work FM simplex and repeaters when the HF bands are not ...
1
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1answer
178 views

What type of digital mode is this?

Currently trying to figure out what type of digital mode I'm listening to. I've purchased a Vaisala Radiosonde RS-92AM. It's a meteorological device usually attached to below a weather balloon. I've ...
1
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2answers
3k views

What kind of wire is best to use for connecting a FM radio to the antenna?

What kind of wire is best to use for connecting a FM radio to the antenna? This article doesn't say what kind of wire is used.
1
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1answer
185 views

Toroidal inductor and transformer basics

In basic terms, using an Ultimate3S Beacon (above) as an example, what do the various toroidal components do exactly? How do they accomplish this? In construction terms, does it matter if the wound ...
1
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1answer
145 views

Track cubesat with webSDR, is is feasible?

WebSDR is a Software-Defined Radio receiver connected to the internet. Here is being said "OK for HF but no good for VHF / UHF". I was thinking to use it for cubesat reception but given that the ...
1
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2answers
261 views

Software TNC's for Linux? (targeted to BPSK1200)

Are there any software TNC's (like SoundModem) for Linux? This is limited to the ones which deal with BPSK1200 (used by cubesat projects). For some cases Warbler will suffice.
1
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1answer
104 views

Transmitter won't transmit with antenna installed

I built a node for my friend out of a baofeng BF-888s UHF transceiver. I am powering the radio with a voltage regulator, and a few caps with a wall wart power supply. The radio will transmit fine ...
1
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1answer
276 views

Determining the correct sidelobe envelope

I need to determine the correct sidelobe envelope for various VSAT antennas. Given the radiation pattern (this one, for example http://www.gdsatcom.com/vsat/technical_docs/patterns/6000-023.pdf), how ...
1
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3answers
172 views

Using two radios for a faster data rate

The maximum data rate on UHF is 56kbaud. This is well over most "high-speed" 9600 baud transmissions. Is it possible to use two receivers at one site, and two transmitters (vice versa when the ...
1
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2answers
403 views

Inverter noise on my signal

I recently built a sound card packet TNC and it is working fine under my standard laptop power supply when I hook it into the wall. When I plug my computer in via a car inverter (12VDC to 120VAC), ...
1
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1answer
148 views

Wideband impedance matching

I'm using an antenna that works in the range from 1 GHz to 3 GHz. I want to match impedances between a cable from the transmitter and the input amplifier and from the output amplifier and the cable to ...
1
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1answer
296 views

AFSK signal will not decode

I'm trying to demodulate an AFSK signal. My device uses 1200 baud rate and 1200/600Hz as mark/space. I tried using almost every software for demodulation, but nothing worked. Most recently, I tried ...
1
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1answer
66 views

What is the forward protocol for FBB?

Does anyone know the forwarding protocol used by FBB? I am working on a program in C# and looking for the protocol to make compressed forwarding etc.
1
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1answer
44 views

Determining modulation by spectrum

Is it feasible to determine what sort of modulation is used for a given signal by looking at the spectrum / FFT? Does software like this exist?
1
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1answer
1k views

Baofeng UV-5R Split mode

I recently purchased the Baofeng UV-5RA. I am trying to set up dual watch mode so that I can receive one frequency, and be able to transmit on another frequency when I key the radio. I enabled TDR ...
1
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2answers
311 views

Antenna + LNA Design Questions

I am trying to design and build an antenna + LNA board. Antenna: http://www.yageo.com/documents/recent/An_FR4_1690_2405_0.pdf LNA: http://www.avagotech.com/docs/AV02-1237EN The antenna is specced ...
1
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2answers
118 views

Logging a contact over a mesh network

Is there a way to log contacts over a mesh network, using TQSL/ LOTW/ EQSL/ etc? If so, how should it be logged.
1
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1answer
138 views

Magnum 257 & Firestik 3' Tuning

Trying to tune a Firestik antenna connected to Magnum 257 on my '98 Jeep Wrangler. Having trouble with SWR reading as it is reading too high (~4) after I set needle on FWD and then switch back to REF. ...
1
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1answer
482 views

In which direction should single wire antenna in underground parking be pointed?

In our collective building lot we have an underground parking, in which a company recently changed a functional garage door system, since then the reception is a lot worse than before. (Like it doesn'...
1
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2answers
251 views

KN-Q7A - A good place to start? [closed]

I have decent circuit knowledge and would like to get into some homebrew operating, specifically voice. Would the KN-Q7A be a good place to start? If so can I just get the parts and do the circuit ...
1
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1answer
1k views

Can the TS-570 be fully controlled over RCP-2?

A fellow amateur here in VU-land reported the display on his 570 died. Apparently the 570 has a proprietary computer interface called RCP-2 ; Are all features on the rig available on the RCP-2?
1
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2answers
492 views

VOIP link to repeater- simplex or duplex?

I have obtained permission by the Rocky Mountain Radio League to link my AllStar linking system node to their repeater via RF or on the input frequency. Since they have such a long tail, they will ...
1
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1answer
383 views

What is the best resonator in Yagi antennas?

As we saw many design for this Yagi feed point. Q1 . Which one would be the best resonator / driven? Gamma match, T-match, delta match, folded dipole, quad, loop? Q2. And what is the reason if ...
1
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1answer
323 views

How do you operate an “up 3” split dx station with a Kenwood TS570 or similar HF radio?

My Kenwood has "split" and "rit/xit". Is the "split" mode suitable for operating a split for a DX pileup situation, where a station is listening "3 up"? I'm confused about which of the larger or ...
1
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1answer
3k views

Remote control for Icom IC-7100

I just got my new Icom 7100, and while I'd love to operate it locally, there are just too many things near me that get interfered with from RF. As such, one solution is to remotely control it - I ...
1
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2answers
2k views

How to make a loop antenna for HF?

While researching this answer, I came across information that indicates that a many good Low Frequency/ Very Low Frequency antennas are loops, with high directionality and good overall characteristics....
1
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1answer
831 views

Spacing between words in CW using Farnsworth timing?

What is the proper way to calculate or determine the amount of time between words (the key up of the last character of one word to the key down of the first character of the next word) when using ...
1
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1answer
2k views

Homebrew 2 meter Yagi construction

Here is what I have • A Baofeng Uv-82 transceiver • A 1/2 inch 10 foot PVC pipe • 3 1/4 inch x 36 inch Aluminum rods • 2 1/4 inch x 48 inch Steel rods (I know they'll rust, it's just temporary to ...
1
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1answer
88 views

Where to find FM satellite information

I'm new to satellites and I am trying to find all the information for everything. Where can I find a list of all the operational FM amateur satellites with the down-link and up-link frequencies? ...
1
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1answer
1k views

How do I build an portable FM transmitter?

I have been bugged with the idea of building a radio in a suitcase, but I have not many clues about where to start. My idea is to make a portable FM station so podcasts can be broadcasted in a small ...
1
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2answers
230 views

How is the 10 m band performing now in January 2014? [closed]

I bought a 10m radio on eBay back in 2007 during the solar minimum when 10m propagation was nothing to write home about. I verified that the radio worked at that time, though it didn't seem to work ...
1
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0answers
19 views

Baofeng UV5RA charger station error

I recently bought 2 Baofeng UV5RAs from the same vendor. Neither of the charging stations work. They both flash green/red immediately upon plugging them in--before any battery is seated! When I seat ...
1
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0answers
54 views

Would a phase compensated sinusoidally spaced folded dipole present less noise to a receiver?

I am attempting to design an antenna similar to a TTFD, double zepp or array of end fed wires, with a sinusoidal, with the period of the wavelength, spacing that causes additive waves on the target ...
1
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0answers
36 views

LA1185 FM downconverter shows weird behavior

I've built FM CCIR/OIRT downconverter based on Sanyo LA1185 IC. I've used most famous schematics for it with slight modification (added DC blocking capacitor 1 nF rated on the output) Coils L1 and L2 ...
1
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0answers
94 views

Extremely strong QRM on VHF?

I don't usually operate in 2 m, save for FM satellites. I usually go to a nearby park when I do this, for better view of the horizon. But I tried working them from home for the past couple of days, ...
1
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1answer
71 views

144Hz monitor with freesync noise on 40m

When I tune on 40 m (7.074 MHz USB as test frequency for there's FT8) and turn on my PC with a monitor that's 144 Hz refresh rate and has freesync on, it starts to make noise and makes signals almost ...
1
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0answers
30 views

power limit on wireless FM microphone transmitters [duplicate]

I am building a "toy" radio station as a teaching tool for high school students to work with. I intend to use a small (short-range) wireless FM microphone module as the transmitter. What is the legal ...
1
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0answers
39 views

UK Intermediate training a not qualified newbie

I'm 99.9% certain that this will be OK, but independent verification would be reassuring. I am an "Intermediate" licence holder in the UK. This means that I am authorised to design and build my own ...
1
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1answer
205 views

How to send DMR SMS using MMDVM modem or hackrf?

I have a baofeng DMR radio with SMS feature, and since there is not much DMR radio owners in my area I want to do something myself. The easiest thing I can do I thought is to send myself some SMS as ...
1
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0answers
61 views

HF propagation prediction using machine learning

Anyone out there know of or developed s/w to predict HF conditions using ML?
1
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0answers
91 views

Compare signal strength with Software Defined Radio

I want to compare field strength with an RTL-SDR dongle or HackRF One. With comparing I mean being correct relative to one another, like if I know field strength of one in mW/m^2 then I know the other....
1
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1answer
60 views

Controlling the number of samples

In the below simple qpsk_tx_uhd flowgraph I am trying to create a slider to control the number of samples but got a bit confused with which parameter I should be ...
1
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0answers
39 views

uhd_packet_rx do not work

I was trying to set up packet communication using examples in gr-digital/examples/uhd_packet_tx and rx. uhd_packet_tx is doing fine, but on receiver side(uhd_packet_rx) is freeze when i check up the ...
1
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0answers
179 views

Capturing Bluetooth / WiFi on an SDR

I have a question, right before purchasing SDR for some tests: Commercial hardware for bluetooth (even Ubertooth) allows you to receive packets on a 1MHz channel. Which practicaly means that if you, ...
1
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0answers
103 views

communication with underground mines?

I have a meter that will analyze limited RF spectrum in my area. One frequency that keeps coming up is 2.498 kHz. An FCC site listed that as the frequency used to communicate with underground mines. ...
1
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1answer
83 views

Is this antenna “system” really work? [closed]

I posted yesterday asking how can I have signal inside my house which my house is obstructed by a hill from direct signal from the cellular's operator' Base Transceiver System (BTS). The schema of the ...
1
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0answers
76 views

How do I Construct a Simple FM Antenna?

I recently bought a cheap stereo amplifier with built in FM receiver from Amazon at the first link below. Testing it out today I found the FM reception to be sub-par. All of my local stations that I ...
1
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0answers
39 views

Problem to paralel tv digital reciever [closed]

Here is my C-Band parabolic tv digital receiver. As shown by the pictures, the incoming coax cable (INPUT) connected both the outer and the core. One goes to digital receiver 1 (receiver 1), and ...
1
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0answers
77 views

Trouble with osmocom source

I'm having trouble running a simple flowgraph with an osmocom source and a qt gui sink. If I run the file with a waveform generator instead of the osmocom source, all is well, the plots appear as they ...
1
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0answers
57 views

Microwave kiln for glass [closed]

I am building a 1000W microwave kiln for glass jewelry. The internal capacity needs to be around 5 litres. What internal dimensions of the cavity should I avoid, or strive for, to ensure even heating....

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