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2
votes
2answers
335 views

What is the difference between Rf Gain Blocks & IF Gain Blocks?

As advertised on websites of large manufacturers like Analog Devices And Texas Instruments I am aware of the difference between an IF stage and an RF stage, however, I was curious if there was any ...
3
votes
1answer
624 views

Kenwood TM-241A direct discriminator out

I am going to do a simple SIMPLEX all-star node, using the URIx USB radio interface, which I just got. I have a Kenwood TM-241A transceiver. I was told the speaker out jack is not sufficient: The ...
12
votes
3answers
4k views

Share antenna between receiver and transceiver?

I recently put up a fan dipole for 80/40/20/10. I'm looking for a way to share this antenna with a receive-only SDR and my shack transceiver. Obviously I can just switch this antenna between the two ...
3
votes
2answers
2k views

Choosing simplex frequency as a technician

My brother and I just got our technician class license. We live close enough to each other that we can use simplex on 2 meters or 440. How do we go about choosing the best frequency to use?
2
votes
2answers
318 views

Linksys WRT54G turned in to a brick

I just bought my first WRT54G (V3), and wanted to build a mesh network (Using the Broadband-ham firmware, http://www.broadband-hamnet.org/ , which as I understand is based on OpenWrt). I wasn't paying ...
7
votes
2answers
537 views

Options for family short range communication in an emergency

I work in an office building about 3 miles from my apartment. I live in a medium sized city in the US. I have thought about getting a pair of walkie talkies for communicating when the cell phone ...
3
votes
2answers
800 views

Some softwares that can decode CW, AX25, RTTY, PSK etc [closed]

What are some softwares that can decode CW, AX25, RTTY, PSK etc? Hope that the softwares provided are freeware or open source.
3
votes
1answer
1k views

Antenna Tripod for a vertical antenna

I'm considering buying a vertical HF antenna (Such as the Cushcraft R8), and a tripod antenna stand, such as the MFJ-1918, and setting it up on my back porch when I'm operating (Which won't be all of ...
3
votes
1answer
593 views

How to connect this Active Antenna Loop and 100MHz Upconverter?

I have bought the two devices in the image. The 100MHz Upconverter with a SMA connector is used to upconvert HF/MF signal for RTL-SDR to demodulate. I found that there is signal from the antenna (...
5
votes
1answer
2k views

What is the difference between a scanner and a receiver?

What is the difference between a scanner and a receiver?
1
vote
1answer
652 views

What denotes no RF output in SSB and CW? [closed]

I have that problem currently with my HF transceiver: no power output at all in SSB and CW, no matter which band / Frequency, but everything is ok in AM, FM and RTTY... There is also a big difference ...
1
vote
1answer
125 views

Comparing antenna effeciency

Let's say I have three dipoles, one is resonant at some frequency and is matched at the antenna, the second is shortened with loading coals and is also matched at the antenna, the third is shortened ...
4
votes
2answers
1k views

How to mark SWL contacts on eQSL?

I fairly frequently get SWL reports via eQSL. I'm never quite sure what I should do with them. I know that eQSL has SWL capabilities, but I can never tell if I'm actually stating that a contact was ...
21
votes
1answer
7k views

Is “just listening” on EchoLink considered bad etiquette?

I was reading about EchoLink and came across this rule under "Access Policies": 2. No "SWL" (listen-only) access is permitted. EchoLink is a two-way system by design, and there is no mechanism ...
6
votes
1answer
1k views

What should be the modulation when transmitting APRS signal?

Is it SSB or NFM or other type of modulation?
5
votes
1answer
105 views

Must all three VEs hold the required licence class to “prepare” an examination, or just one?

47 CFR § 97.507 states that: (a) Each telegraphy message and each written question set administered to an examinee must be prepared by a VE holding an Amateur Extra Class operator license. A ...
1
vote
0answers
208 views

Designs for a multi band vertical/collinear antenna for the 1.9 gigahertz range [closed]

I'm starting to research building a multi-band antenna in the 1.9 gigahertz range. I see them offered on wireless routers, and they use them in cellular sites. Can anyone provide a reference or quick ...
9
votes
2answers
5k views

How can I calibrate a SWR meter?

I would like to build my own HF (1.8 - 30 MHz) SWR meter, however I'm not sure how I can calibrate the meter without an accurate power source. I'm targeting a power capacity of 150 W so I can use it ...
4
votes
2answers
3k views

Does effective grounding of mobile (vehicle) antenna mounts address common-mode currents?

While researching how best to install my mobile amateur radio in my car, I didn't understand if there was optimum Antenna Feedline Length for mobile installations? Understanding that this is caused ...
5
votes
3answers
294 views

Why is gain used?

It always confused me why 100 watts out of your transmitter could radiate 200 watts coming from a high-gain antenna. Why is the term gain used instead of directionality?
11
votes
2answers
4k views

Is there an optimum Antenna Feedline Length for mobile installations?

I bought a ham radio antenna mounting kit for my car that includes ~16' of coax. One end has a trunk lip NMO antenna mount, the other end has a re-solderable PL-259. I asked the sales person if it is ...
3
votes
1answer
814 views

Using wirewound resistors in a dummy load

I have a bunch of high-wattage 50 ohm resistors lying around, but they are wirewound. If I use them as a dummy load for transmitters 144 MHz and down, how bad would that be? Since they probably will ...
2
votes
2answers
2k views

In USA, is it legal to hear police or ATC frequency? [closed]

In USA, is it legal to hear police or ATC (air traffic control) frequency?
3
votes
1answer
136 views

What are specific areas that some people get into within amateur radio? [closed]

I just got licensed a few weeks back and have been connecting with repeaters on my 2m/7cm HT. My plan is to get a mobile antenna for use in the car and make an antenna for home operation. While those ...
2
votes
1answer
401 views

What does the “USER” programmable key function do on the Yaesu FT-897D?

I was just reviewing the manual of my Yaesu FT-897D to remind myself of useful functions I might have forgotten about, and I found the programmable function keys, which can be set to any of “All Multi ...
8
votes
1answer
911 views

Is a VHF antenna on a vehicle's body a bad idea?

For context, I'm brand new, with nothing but an HT & 19" dual band (2m/70cm) whip on it. While I'll likely go with a magnetically mounted vertical antenna, I've been thinking of other more covert ...
3
votes
1answer
235 views

What is radio pollution?

In a slide on calculating link budget, detrimental effects to a link included “Radio pollution (selectivity, blocking, IP3)”. What is radio pollution? Specifically, what are selectivity, blocking, ...
13
votes
1answer
2k views

How would a time-difference-of-arrival receiver with two antennas know which side the signal is from?

An easy TDOA design by Byonics was published with the following schematic: It appears that the antennas are switched at a rate of 640Hz, which allows a 640Hz tone to be heard in the radio when the ...
8
votes
3answers
6k views

Why is the electric field orthogonal to the magnetic field from an antenna?

I've read in several places that the electric field is 90 degrees orthogonal to the magnetic field, and both are orthogonal to the direction of the wave from a transmitting antenna. What causes this? ...
7
votes
1answer
697 views

Why are there no amateur allocations in the LF and VLF spectrum?

Amateur radio enthusiasts have slices of spectrum at every magnitude of spectrum MF and above, but in the US none are below MF. Why are there no spectrum allocations below 160M?
3
votes
1answer
618 views

Audio Morse Code to CW converter?

What kind of circuit can be constructed and/or could be used to convert audio containing Morse Code sounds (say from an old practice tape, or from computer generated audio) into key, switch or relay ...
3
votes
1answer
150 views

How do PL tones make it through so much noise?

So sometimes I hear people trying to get into a repeater with pure noise, and no audible audio on their transmission. With the repeaters that require a PL tone, how can the PL tones get through all ...
2
votes
2answers
1k views

What is a “dip relay” and how does one use it to build a transmitter?

Reading a discussion on low parts count transmitters, I came across this description, which lacked schematics and build instructions: Re: PROJECT 14: THE WORLD'S SMALLEST TRANSMITTER Are y'all ...
10
votes
3answers
5k views

Why prefer LC oscillators rather than RC oscillators in RF design?

I don't recall ever seeing an RC oscillator driven RF transmitter or receiver. What prevents people from choosing RC oscillators in RF design?
10
votes
2answers
4k views

What is the expected microphone input voltage level of a handheld transceiver?

Ok, so I'm looking to inject some computer generated CW into a little handheld rig by wiring direct into the mic input line. What sort of voltage is expected on this input, are we talking uV, mV or ...
16
votes
4answers
3k views

Does a FCC amateur license cost money?

If I wanted a FCC Amateur license, is this going to cost me anything? That includes tests, application fees, filing fees, and anything else but hardware.
14
votes
1answer
7k views

How do I change my registered address with the FCC?

I just moved, and I want to change my registered address with my call-sign. Is there a form or something somewhere that I can fill out? Do I have to mail it, or can I turn it in to the FCC or ...
5
votes
3answers
1k views

Where to apply for an amateur LTE radio license in the USA?

Where do you apply for a license to operate on the LTE radio spectrum for amateur radio in the USA? Can this amateur license be used to operate a cell phone independent of a carrier?
-2
votes
1answer
121 views

multiband mimo ad-hoc wireless connections from different spectrums [closed]

I'd like to create a multiband MIMO ad-hoc wireless network. Can I turn on every GPS, WIFI and Bluetooth radio of a mobile device and synchronize data transfers at extreme speeds between a small, ...
3
votes
1answer
103 views

Estimate Path Loss

I am wanting to setup a simplex path that is 7KM from base to base in relatively flat ground. How can I estimate the path loss, and what do the numbers mean when I find them? I am wanting to do it ...
6
votes
3answers
488 views

Morse Code Key Grease

I just got an old brass key at a hamfest, and it appears to be in pretty good mechanical condition, aside from some dirt and dust. Taking it apart, the key (apologies for not knowing the exact ...
4
votes
1answer
380 views

AM vs SSB weak signal

I know single sideband is much better than FM for weak signal receiving. I know that SSB is just like AM, but with the unneeded parts removed. For weak signal propagation, like EME and aurora, would ...
9
votes
1answer
2k views

Antenna RX vs. TX

If I only want to receive radio signals and not transmit, are there any differences in the way I design the antenna I need to use, or is it the same either way? I was going to pick up a Realtek ...
5
votes
1answer
1k views

Why is optimal polarization different for fm as to SSB/CW

On the article "7db for 7 bucks", which is an article about building a simple three element 2M yagi, they stated that vertically polarizing the antenna is better for FM work, and horizontally ...
3
votes
2answers
906 views

What is Circular Polarization?

So I just learned that a satellite does not send out a circularly polarized signal, it just switches orientation slowly when it topples through space. I thought that because they were spinning, the ...
8
votes
2answers
221 views

What will I need to receive the ICE/ISEE-3 transmitter?

The ICE/ISEE-3 spacecraft, launched in 1979, is due to pass by the earth in August, 2014. It was commanded to power down completely years ago, but it appears to have failed to do so, and while it ...
9
votes
2answers
2k views

Are satellites Left or Right hand circularly polarized?

I'm thinking of building some helical antennas for satellite work. I want to know which way to wind them. If satellites are spinning randomly, how can we know if they are left hand or right hand ...
2
votes
2answers
286 views

Measurement Confusion

I am building a simple antenna from this article 7db for 7 bucks. I am confused on the measurements for the antenna: It looks like there are two pieces of 18 inch PVC pipes connected to a T fitting. ...
6
votes
1answer
676 views

Coherent CW synchronization?

When using coherent CW, how is the receiver frequency and/or Morse Code dot clock synchronized to the transmission precisely enough to allow for synchronous decoding?
6
votes
1answer
2k views

What does the Friis transmission equation represent and how is it derived?

I've read that the Friis transmission equation can be applied to calculate path loss in ideal space. However, I'd like to better understand the factors that define it and what it represents, and why ...

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