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4
votes
1answer
833 views

How to make an inductor?

I am a high school student and am making a project on FM receiver for class 11. I am following this circuit diagram: The L2 in this diagram is a 22µH RF Choke. The part listed in the website has the ...
8
votes
3answers
863 views

What happens in a low loss feed-line with a high SWR

I was recently reading an interesting article from the ARRL to get a better understanding of the SWR. The following case is still unclear: A low loss feed-line with an impedance that doesn't match ...
3
votes
2answers
975 views

Linux APRS client

I have an old PK-232 packet TNC which is spitting out APRS data from 144.390 to the serial port. I have confirmed this with minicom and see all sorts of data with lat long etc. I would like to view ...
5
votes
3answers
873 views

Is possible to make small HF microstrip or helical antenna by using high permittivity dielectric material?

Is possible to make small HF microstrip or helical antenna by using high permittivity dielectric material like SrTiO3 ?
8
votes
1answer
2k views

How are DTMF tones sent through a mic?

In the following diagrams, a microphone pinout is shown for several radios which have DTMF mics that work with them. How is DTMF sent to the radio without a pin designated "DTMF"? Is it through the ...
8
votes
5answers
11k views

What frequencies should I listen to for packet radio?

I just obtained a really old packet TNC and hooked it up to the computer, and it appears to work. Is there a standard packet calling frequency on 2 meters? I would like to see if there is packet ...
9
votes
3answers
4k views

Remote SDR on the internet other than WebSDR?

Besides WebSDR, what remote Software-Defined-Radio stations (for shortwave or amateur bands) might be available for open public access over the internet? What protocols do these SDR stations use to ...
12
votes
3answers
9k views

Protect rig from static charge on antenna

How can I continuously discharge static from my end-fed antenna? My Electraft K2/100's autotuner (schematics) has an SWR bridge using two 1N5711 pin diodes. These diodes get blown if any static ...
6
votes
2answers
2k views

What protocol or API does WebSDR use to stream audio?

What documented protocol or API does WebSDR use to stream audio over the internet? I'm interested in capturing a WebSDR audio stream using a small embedded device which has lots of audio DSP ...
5
votes
1answer
2k views

maximum acheivable range on CB radio by ground wave? [duplicate]

I have 10 watt CB radio system & 0.64 lambda monopole antenna , I think it has a 5 dBi gain . what is the maximum acheivable range by ground wave in an urban area ? If I want to increase my ...
3
votes
1answer
92 views

How much distortion would aluminium wire stays for the centre-pole on my inverted-vee cause?

I used nylon rope from the nearest hardware store to stay the centre-mast on my inverted-vee for the 20. The centre-pole is a long long looong bamboo. The trouble is rain here really isn't friendly to ...
4
votes
2answers
351 views

Recommendations for starting out with HF for an amateur

I'm a beginner who's nearly half a year from receiving my ham license in India. I want to start with HF radio and wish to build my own rig. Currently I have looked and multiple designs using the ...
3
votes
1answer
119 views

Are the Icom 2300 h and Ftm 400dr DC cables interchangable?

I would like to swap out my 2300h to a 400dr. Would rather not swap out dc power cable. Are the cables the same or is there an adapter for make it possible?
3
votes
2answers
2k views

Longest achievable ground wave range on 40-meter bands [closed]

What is the longest possible range on the 40-meter band by ground wave? A reference said we can achieve 150 miles at 8 MHz with only a 100 watt transmitter. It also says on 160 meters, the ground ...
12
votes
5answers
19k views

What's the difference between saying “CQ” or “QRZ” in a contest?

I'm listening to (or let's say I'm trying to participate in) a contest (or perhaps Field Day), using SSB. I noticed that a station would, after completing a contact, sometimes say “CQ” and sometimes ...
2
votes
2answers
1k views

High data rate on HF & MF bands

Is it possible to transfer data at a high rate, like 1-2 Mbps, on 0.5 - 30 MHz? From Shannon's Theorem, with a bandwidth of just 300 kHz it is possible to reach 1.5 Mbps. I want to use these bands ...
2
votes
1answer
115 views

How can I render my 2.4GHz antenna directional?

With barely no knowledge in this field, I would like to render my antenna used with Bluetooth BLE devices more directional. I tried to shield the antenna with different kind of metals with no luck. ...
7
votes
2answers
340 views

Center frequency spike on software radio for mismatched/disconnected antenna

A while ago I was using a software radio receiver to perform some antenna analysis. I left the spectrum display on while disconnecting the cable and noticed that when the cable was disconnected I ...
1
vote
1answer
300 views

Can the IC-R6 scanner receive NFM

I am considering purchasing the Icom IC-R6. One of the determining factors, and my questions is, can it can receive FMN (I believe that is narrowband FM)?
1
vote
2answers
9k views

What is DMR and can I listen to it?

I saw here Table of broadcasting stations that there is a mode called DMR (under Atlanta Technical College). What is DMR and if I buy a scanner (I am thinking about the Icom IC-R6) could I listen to ...
2
votes
2answers
96 views

How does a scanner work [duplicate]

I was reading What is the difference between radio scanner and receiver? and I saw that it said that the scanner continues on scanning after a radio transmission is over. If I find a frequency that I ...
1
vote
2answers
139 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.
10
votes
4answers
592 views

Why are commercial SDRs so limited in operating frequency?

I spent a bit of time researching SDRs, mostly looking into the possibility of building an all-FPGA-based TRX. There are a lot of commercial ready solutions; some are cheap, some not, but they all ...
5
votes
1answer
1k views

Is the Kawamall DMTF 6pin microphone usable with the Kenwood TK-805D radio?

I have a Kenwood TK-805D commercial radio, which I am using for UHF ham operation. For repeater usage, with AllStar, IRLP, and Echolink, I need a DTMF mic for it. I did a search on the internet, ...
2
votes
3answers
1k views

How to shorten the length 50 ohm characteritic impedance antenna cable

I have two 50 ohm characteristic impedance cables of which I need to shorten their length to compact my design. (put everything in to a box) The cables I need to shorten are the GPS & GSM antenna ...
2
votes
2answers
135 views

Terminology for written “CW-like” Code?

Morse Code is defined by most dictionaries in terms of sequences of short and long signals. What would be the most common or most descriptive terminology for un-timed written or printed code, where ...
2
votes
2answers
4k views

How to eliminate alternator whine?

On my car's LW receiver, I have a severe case of alternator whine, especially when the headlights are on. It has become worse over time. I have read that capacitors might help. However, two things ...
4
votes
1answer
4k views

Can I improve reception with a more sensitive antenna / preamplifier / better feedline?

I am trying to receive a station, but I can only barely hear it through the noise. Will doing anything that increases the signal from my antenna help, such as: using a more sensitive antenna adding a ...
3
votes
1answer
633 views

Idea for better reception in crowded city

I am living in crowed area of a city. It is impossible for me to set up an antenna outside the apartment. I receive signal inside the room. I have a funcube dongle pro+ and some RTLSDR, the picture ...
2
votes
1answer
3k views

Decoding the Morse code

I am using a crystal to transmit morse codes, and I am using Kenwood radio receiver to obtain the signal. It receives the signal with a lot of noise, though we can figure out the morse code sound. I ...
4
votes
2answers
218 views

Antenna Design for specific directions

I am designing an antenna for a device and was hoping to gain some insight in the correct design direction for the antenna. The Idea: A receiver & antenna that fits in a 6" diameter by 3" deep ...
2
votes
1answer
86 views

In Canada do I need an Advanced license to use a DVAP?

In Canada do I need an Advanced license to use a D-Star DVAP hotspot?
3
votes
2answers
1k views

2m Homebrew Receiver - Chip for frequency [closed]

I am a new HAM trying to design a small, cheap 2m receiver. I've been looking up different circuits and homebrew tutorials, but the closest I seem to find to what I'm looking for seems to always use ...
7
votes
1answer
142 views

Can club stations register callsigns on the D-Star network?

Some of the members at my local radio club are interested in working with D-Star. Since the equipment is very expensive, it was proposed that the club purchase and operate one rig collectively. Is ...
5
votes
1answer
300 views

What is a general procedure for aligning directional antennas?

I want to establish a microwave link (1.2GHz) between two stations using antennas with a directional radiation pattern. The stations have a clear line of sight to each other. Each antenna is attached ...
10
votes
1answer
253 views

Is calling the Palmer Station (Antarctica) via IRLP without prior arrangements acceptable practice?

Until I can get an HF rig, I've been using my HT through a local repeater IRLP node. I've successfully made a few contacts doing that, but I recently noticed that Palmer Station in Antartica has an ...
4
votes
3answers
4k views

What are the geographical restrictions in using the 70cm band in the United States of America?

Geographical restrictions exist for various frequencies in terms of usage in the United States of America as stipulated in 47 CFR 97.303. What are the restrictions, if any remain, in terms of ...
5
votes
1answer
177 views

Can unlicensed users operate at a Canadian club station?

I am a radio amateur licenced in Canada and a member of a local club station. At a recent meeting, someone asked me whether they could operate at the station if they did not have a radio licence. I am ...
6
votes
3answers
777 views

2.4 GHz Antenna for RC copter

What is the best omni-directional antenna design for any RC flying objects? Many times I've lost signal and my copter falls due to lost signal. (Using default antenna). Since the receiver and ...
9
votes
3answers
1k views

Using ham radio bands for telemetry

If I built a machine that went far away, say a buoy, would I be allowed to use ham radio frequencies to transmit telemetry data back to its base station, if I used my call sign? This is for personal ...
1
vote
2answers
3k views

Is there a way to find out the location where a radio signal is intercepted?

I am a software engineer and a noob to radio. Is there a way to find out the location where a radio signal is intercepted? That is, the location where somebody is eavesdropping on my wireless ...
3
votes
1answer
289 views

SSB modulation image rejection

I'm trying to figure out how SSB transmitters manage to get rid of the images created when mixing up audio frequencies. For example, when mixing a 1KHz signal with a 7MHz one you will end up with two ...
2
votes
3answers
2k views

Are there legal restrictions on radio reception in India?

I live in India and would like to know whether it is legal to listen to on the air transmissions there. I know that transmitting is allowed only in limited frequencies and strictly require a HAM ...
2
votes
1answer
125 views

Is this beacon the tail end of a 'Numbers Station' broadcast?

I was recently scanning through the short-wave frequencies and stumbled upon a series of repeating tones, which then cut to classical music and then a woman speaking French (unconfirmed). Later I was ...
6
votes
2answers
246 views

How do I keep the bomb squad from winning a foxhunt?

I want to hold a fox-hunt in a relatively public location, such as a park or college campus. The fox that I've built uses an ammo can with a rubber duck antenna. It occurred to me that this ...
6
votes
5answers
11k views

Wifi passive repeater (antenna to antenna connection)

I have two buildings. Building A has wifi (2.4GHz) infrastructure, Building B doesn't. One side of building B can pick up the wifi signal from building A. I want to passively extend the signal through ...
1
vote
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. ...
3
votes
1answer
202 views

Would a switched RF attenuator be (a)symmetric?

I picked up this 0-80 dB switched RF attenuator at a flea market, with no part number or other useful markings other than the knob settings. I've tested it and confirmed that it works, but there's one ...
0
votes
1answer
182 views

audio amplifier as fm amplifier possible?

Is it possible? I know it depends on legal issues; it is just for testing. I will "transmit" from RPI (Raspberry pi as fm transmitter).
1
vote
1answer
581 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'...

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