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5
votes
2answers
331 views

BAOFENG UV-5R for cubesat communication on lab, does it work?

Here we have a cubesat which operates in VHF/UHF. Communication with it (from a ground station perspective) is done with an Icom Radio. Would it be possible to replace it with a cheaper BAOFENG?
4
votes
2answers
488 views

Are there any satellites with 435 MHz uplink?

I have a transceiver working in the 435 MHz ham band. I want to test my uplink capability by communicating with satellites operating in this band. Are there any digital satellites which I can use for ...
5
votes
4answers
459 views

Will Icom HM-133 work on IC-2800H

I have been having problems with the knock off of Icom microphone so I figured I would bite the bullet and get a new Icom microphone, since the original is out of production. I found that HM-133 looks ...
3
votes
5answers
538 views

Crystal set as wireless earphone

Reading about a 'necklace' coil inducing a strong alternating audio current (using an LM386 f.i.) into a magnet inserted in the ear canal set me thinking. The problem is that the magnet has to be ...
5
votes
2answers
2k views

What is an cheap and easy to build kit for a sw ssb transceiver? [closed]

I have a licence since I was 14 which is exactly half of my life, but honestly with the advent of the internet I somehow lost interest and sold my equipment. Now I really start to think, I should ...
15
votes
2answers
2k views

How does selecting the opposite sideband when receiving CW on HF reduce interference?

I am studying for my FCC General Class license, and question/answer G4A02 reads as follows: Q: What is one advantage of selecting the opposite or "reverse" ...
0
votes
1answer
182 views

How does a multi-element vertical work?

For example, Diamond makes the X700HNA which is stated as a 4x5/8 vertical on 2m. Does this just mean that it is 20/8 wavelength long vertical? Or is there some magic to phasing the 5/8 segments? I'...
2
votes
3answers
556 views

Should I use ham or cb radio? [closed]

I've been scouring the internet for the answer and my question is never directly answered, usually there is a bunch of technical jargon. It is not that I am unwilling to learn, because I want to, but ...
4
votes
1answer
2k views

How to measure gain of an antenna?

I have dual stacked crossed yagi antenna. How can I practically measure the gain of the antenna combination? I know that this can be done in an anechoic chamber. But this is not feasible for me (...
2
votes
1answer
160 views

Ferrite Rod Price Differences

We are trying to make a VLF geophysics device for our graduate project and we need two ferrite rod antennas (desired length is 6"). Searching on the internet, we have found two ferrite rod suppliers. ...
2
votes
1answer
4k views

Baofeng UV-B6 transmits no audio

I have this Baofeng UV-B6 (the same as B5), and after using CHIRP a few times, transmission stopped working. In fact, it starts transmitting, but no voice is sent whatsoever — dead carrier. RX works ...
1
vote
0answers
85 views

Best frequency for very local dense building chat [closed]

Let's say everyone has general liscense classes and can erect antennas to whatever can fit on the human body. What would be the best frequency to talk locally in an area with lots of buildings and man ...
4
votes
2answers
600 views

How should I mount a mobile antenna on a vehicle with a non-conductive body?

I would like to mount a self tuning antenna, ATAS-120, matched with the FT-857D transceiver. I would like to make this pair function on an ARGO 8x8 amphibious vehicle with a polyethylene body. There ...
16
votes
2answers
5k views

Is free space path loss dependent on frequency?

Free space path loss is calculated as: $$ \left( 4 \pi df \over c \right)^2 $$ The presence of $f$ in this equation means that losses increase with increasing frequency, so there's an inherent ...
3
votes
4answers
289 views

Can sub GHZ frequency can be used in space communciation?

Is it possible for a sub GHZ frequency (Say 300 Mhz) can be used for space communication for small satellites such as a cubesat? What are the advantages and disadvantages for this.
1
vote
1answer
271 views

why fiber optics replaced microwave [closed]

I was recently reading an article where they mentioned about abandoned microwave towers being replaced by fiber optics. From what I understand microwave technology is better at speeds, is cost ...
6
votes
1answer
260 views

History and significance of term “lid”

What is the history on the term “lid” when referring to a telegrapher’s capability? How did it originate and what is the significance if any of each letter?
3
votes
6answers
2k views

Would it be feasible to set up a SSB or AM 2 meter repeater?

Would it be feasible to set up a SSB or AM 2 meter repeater? I want to set up an AllStar full duplex node and like the idea of AM because stations can double without issues. SSB works for weaker ...
3
votes
2answers
25k views

Can a Baofeng UV-5R+ be used on FRS, GMRS, and MURS?

Is this secure if I was talking to another Baofeng UV-5R+?
1
vote
1answer
365 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 ...
12
votes
3answers
9k views

What is the effect of using different number of radials with ground plane antenna

I'm new to electronics and telecommunication at all, I having trouble with understanding the difference between 2, 3 and 4 radials, as I've searched online I've learned that I can use only 1 radial(...
3
votes
2answers
139 views

Why is 2 meter pre-programed?

When I tried to enter frequencies in my 2 meter YAESU, it was already programmed for 144.000 MHz as the primary. WHY?
9
votes
4answers
11k views

Building a portable event repeater

How does one go about building a portable repeater for use at events? Preferably at low cost, and with a minimum of bulky parts (so it's travel friendly). Obviously you'd need a pair of radios to ...
4
votes
2answers
1k views

Where does one find high-voltage variable capacitors and inductors for RF? [closed]

I'm looking to start building various antenna tuning circuits, but I'm limited by my parts inventory. I have pots and mag wire for winding inductors and a nice spectrum of fixed-value capacitors, but ...
4
votes
2answers
261 views

Can IMAP email be used for packet radio?

I just barely learned that IMAP is a protocol that allows you to read and respond to emails without using the internet. Would it be possible to use this application for packet radio and if so, how? I ...
2
votes
4answers
2k views

Why doesn't adding a resistor inline to a 12 V car charger change output voltage

I purchased a baofeng car charger for my little UV5Rv2 HT. It was advertised to work with the radio, so I didn't think much of it. It turns out, all it does is pass my car electrical system voltage ...
5
votes
1answer
772 views

Why exactly would cable lengths to a duplexer matter?

So a very experienced friend of mine is making a portable suitcase kit with Yaesu FTL-2001 (VHF), Yaesu FTL-7002 (UHF) and DX-720D duplexer* plus power supply and other miscellaneous gear. FTL-2001 ...
3
votes
2answers
583 views

70cm antenna for an apartment

I have a blind friend who can't put anything outside, and is restricted to antennas near the window in his apartment. Luckily he lives closer to the top, which helps with range a little bit. He has a ...
3
votes
1answer
595 views

How can I disable the TOT time out timer of the TM-V71A?

I am using the Kenwood TM-V71A as an EchoLink link station. When I try to play our weekly bulletin, which has a duration longer than 10 minutes, the TOT cuts the transmission short. I do understand ...
5
votes
2answers
13k views

What is the aperture efficiency of an antenna?

For reflector antennas, I see a number called aperture efficiency. What does it mean?
3
votes
1answer
1k views

Simple FM low power UHF transmitter circuit

I want to build an low power transceiver on 33cm or 23cm (or 2 meters, but not recommended because of all the other activity interfering with my stuff) I would like to use FM and just have enough ...
3
votes
2answers
1k views

Will I harm batteries by only trickle charging them, or connecting them to a power supply?

I have some 12V, 12Ah Enercell batteries from RadioShack, RS part number 2301219. As far as I can tell these are AGM SLA batteries. I picked up this 3-stage charger from Harbor Freight and as far as ...
2
votes
1answer
610 views

Vertical dipole as a mobile antenna counterpoise?

I have a NMO mount antenna- 1/2 wave on 2 meters. I am going to stick it on top of a PVC pipe which is 5 feet tall. Since this is a bicycle mobile antenna, I do not have the option of large radials ...
5
votes
1answer
987 views

Why does the ionosphere reflect some frequencies and not others?

Why is it that some frequencies transmitted at some known direction are reflected back to earth, yet others transmitted at the same direction, power and polarity pass through into space with no ...
3
votes
1answer
167 views

Color of radio noise?

Is typical background RF plus radio receiver electronics noise (wide-band audio) closer to white noise or pink (1/f) noise? Does it depend on the demodulation scheme (AM/FS/SSB/etc.), if any, ...
3
votes
1answer
2k views

Counterpoise from artificial ground vs base of antenna

I have an MFJ-934 tuner/artificial ground for my MFJ-1699 multi-band vertical (stuck on a balcony, so limited HF antenna options), and I'm wondering if there's any downside to the counterpoise ...
1
vote
2answers
976 views

Why does the FCC publish station address information?

How do hams deal with the privacy and security concern of your station location (usually a home) having the information published for everyone to see? It seems hams do not have proper concern for ...
3
votes
1answer
8k views

Conversion from Baud to Bits per Second and then to Bytes per Second

How would I go about converting from Baud to Bits per Second (bps) and then from Bits per Second to Bytes per Second (Bps)?
3
votes
3answers
4k views

Setting up a Kenwood TM-D710G for APRS

If I am going to use a Kenwood TM-D710G for APRS, will I need to leave one of the VFOs on the APRS frequency of 144.390 MHz, or does the TM-D710G have a 3rd VFO built-in specifically for APRS use?
10
votes
4answers
935 views

How does an antenna transform impedances along its length?

If I insert some impedance (like a loading coil, or a trap) at the base of a monopole antenna, the effect on the feedpoint impedance is easy to predict: the impedance is in series with the antenna, so ...
3
votes
1answer
526 views

Trap dipole tuning up on the wrong band

I'm building a trap dipole for the high HF bands, 10 / 12 / 15 / 17. So far what I've got in the air is: The 10 meter section (4.92 meters, 16.14 feet, resonant at 29Mhz) The 10 meter traps (...
3
votes
1answer
815 views

How to setup packet BBS?

Here is my goal: To be able to talk to my friend using packet even when He or I are not there using a saving to TNC technique. We live only a few miles away from each other, and have a good signal. ...
2
votes
3answers
5k views

How does the antenna length affect signal transmission/receipt in different bands?

My Canadian Amateur Radio Basic Qualification Study Guide tells me that my antenna length is specific to the wavelength I wish to broadcast on and gives a formula that equates to antenna length = half ...
6
votes
2answers
5k views

How does a folded balun work?

A folded balun is made from two quarter-wavelength, parallel conductors. A picture is worth a thousand words: Here are some pictures of an actual construction from Gisela & Joe Noci on diydrones....
2
votes
3answers
211 views

Multiple transmitters using same frequency

in our wireless network we have a variable count of devices. Each device contains one transmitter and receiver. Both receiver and transmitter are working on the same frequency, 433 MHz. To keep the ...
5
votes
1answer
1k views

Connect Printed Yagi-Uda Dipole Array with Balun to coaxial cable correctly

I am making the Printed Yagi-Uda Dipole Array with Balun (that is the full name). I used Antenna Magus to calculate dimensions. I am not sure how to properly connect it to coaxial cable. Here is what ...
2
votes
1answer
1k views

Radiation pattern for a 1/4th wave 2 meter antenna used on 70cm

What would the radiation pattern look like if I used a 1/4th wave 2 meter mag-mount antenna on 70cm with an HT.
5
votes
2answers
296 views

What are the continuous transmissions at the lower end of the spectrum?

I'm fairly new to amateur radio, and I've been using a web-based SDR tool in addition to my own radios. Using this SDR tool shows a lot of activity lower down on the spectrum, such as this: When I ...
10
votes
1answer
5k views

How to design a rubber ducky antenna

I am attempting to design an antenna for a 162.4 MHz omni receive only application and am confident it is going to be difficult if not impossible. I have very tight specs on space(6" diameter by 3" ...
9
votes
4answers
25k views

How can you calculate the frequencies for each band?

I've just started studying for my HAM license a couple of weeks ago, so please excuse me if this is a remedial question... I have the Canadian Amateur Radio Basic Qualification Study Guide (which I'm ...

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