natevw - AF7TB
  • Member for 7 years, 6 months
  • Last seen this week
Why are radio frequency ranges aligned on multiples of 3?
14 votes

The ITU bands are actually delineated along plain powers of ten! They're just hiding a bit. From the description above a table of all the bands on Wikipedia: As a matter of convention, the ITU ...

View answer
Why does ARRL license examination procedure preclude students from discovering what questions they got wrong on licensing tests
Accepted answer
13 votes

Having participated as a volunteer examiner in a few test sessions, I think there are a number of reasons this is the case: We tend to quietly give the pass/fail results — and should offer the number ...

View answer
FCC tracking of unlicensed FRS/GMRS transmissions
Accepted answer
13 votes

Are there any documented cases of the FCC actually tracking down and harassing/fining/jailing people for illegal FRS/GMRS transmissions of this sort? You can browse the Enforcement Bureau's Field ...

View answer
Would a ham license allow me to use an uncertified radio on other (non-ham) bands I have permission to use?
10 votes

I just purchased a UV-5R to hopefully integrate into business class radios my company uses. Unfortunately, this is not likely legal. Business radio is licensed under the FCC's Part 90 rules; those ...

View answer
What "test transmissions" are allowed above 51MHz?
10 votes

This is indeed in the FCC regulations. In Part 97, section 305 regarding "Authorized Emission Types" there is the following chart which lists two relevant subbands, see in the VHF group the 6m row and ...

View answer
What fraction of 2x2 USA call signs are vanity calls?
9 votes

According to my calculations, about 20% of active 2x2 callsigns in the FCC's amateur radio service database are vanity callsigns. For comparison… 75% of active 1x2 ham licenses nearly 50% of active ...

View answer
Can a ham license be used for a job?
8 votes

If you get a ham license, can you, later on, get a job with that license, or at least display it on a resume. Is that possible. The other answers already cover this pretty thoroughly, so in short: ...

View answer
dBm signal minus dB
Accepted answer
8 votes

Decibels are all "ratios" at their core. A unitless dB is a simply a ratio of one number to another, perhaps input power relative to output power. We can also use decibels for absolute values, by ...

View answer
What's the difference between "maximum usable" and "critical" frequencies?
8 votes

The maps are related, but as this excellent posting describes: The 'critical frequency' is the highest frequency that gets reflected when it is aimed straight up at the ionosphere. However: …...

View answer
Do volunteer exam coordinators provide accommodations for applicants with visual impairments?
Accepted answer
7 votes

Yes, volunteer exam coordinators must provide accommodations for applicants with visual impairments. For the best experience, please contact the test team in advance so they can best prepare for your ...

View answer
RX antenna and RTL SDR with upconverter ..How to hear something?
Accepted answer
7 votes

Fun setup! I have many of the same components and need to try them out myself, but here's a general outline. (Plenty of this may be review for you, but I'm including it for others who may not be as ...

View answer
What is the attraction of vertical antennas for HF?
7 votes

Cribbing a few quotes from answers to related questions, here's a start. From https://ham.stackexchange.com/a/195/1362: The primary advantages of vertical antennas are that they are ...

View answer
help identifying a vacuum tube
Accepted answer
6 votes

This looks like a JAN-CTL-5948A, found via images within the search results for "huge vacuum tube". According to the linked site (from which the picture is also taken): The primary application of ...

View answer
Is HAM the only non-criminal/civil broadcasting a person can do that doesn't own a shortwave radio station?
6 votes

For clarity, I am splitting your question "Is HAM the only legal way to broadcast on shortwave radio?" into two parts: Is ham radio a legal way to broadcast on shortwave from the USA? Under what ...

View answer
What are these antennas used for?
5 votes

UPDATE: I've started a followup question regarding the leftmost antenna, which I originally took to be a discone. See: What sort of antenna would use a bicone or lozenge-like arrangement of vertical ...

View answer
How were 1920s hams able to measure megahertz frequency?
Accepted answer
5 votes

[Discovered this via a comment on another answer.] According to their Wikipedia article: Lecher lines were used as frequency measuring devices until frequency counters became available after World ...

View answer
Can I talk 2 Meter VHF across the United States
5 votes

Sometimes a VHF signal can be heard clearly, thousands and thousands of miles away! The usual mechanism is tropospheric ducting. It's an essentially random, temporary occurrence, not something you can ...

View answer
What is a "feed-through load" and how does it work?
4 votes

I think the correct way to understand this is basically as "a dummy load which makes it easy to measure the voltage across itself". Likely as simple as: simulate this circuit – ...

View answer
Will my neighbor's amateur RF antennas effect my own utilities?
4 votes

The frequencies your neighbor would be transmitting are different than the ones your own communications would use. They should not interfere with your utilities. Occasionally, funny things like old ...

View answer
What to do when accidental emission can't be given a call sign ID?
Accepted answer
4 votes

Practically I think the answer is more or less as Brian says. Mistakes happen and I think it's generally reasonable to simply move on: […] if the unintended transmission was brief, within the ham ...

View answer
What parts / procedure do I need to build a UHF receiver that can connect to a standard pair of headphones
4 votes

Sounds like you are wanting to build a DIY FM receiver that can be tuned over a broad portion of the UHF band. [I'll leave aside any legal implications — but make sure that your goal is permitted in ...

View answer
How does VHF/UHF propagate beyond the expected (radio) horizon?
Accepted answer
4 votes

Turns out that, after turning to discussion of HF propagation for a number of intervening pages, this Antenna Book ends up getting back around to its own answer for this question! From the "Scatter ...

View answer
SDR with the Raspberry Pi
Accepted answer
4 votes

Yes, with some important qualifications, you can "directly" generate SSB on the Raspberry Pi. The rpitx software you mention does that, and in combination with an RTL-SDR type dongle you would indeed ...

View answer
Can you jam jam?
Accepted answer
4 votes

This would be something like active noise cancellation and depending on the nature of the source could be somewhat possible. However, it is not a trivial task. If you imagine trying to cancel out an ...

View answer
Modify a CB radio to connect to a wireless network?
Accepted answer
3 votes

There's a lot of pieces to this question and it sounds like you've already split some of them off to other sites which is good. It's still a little unclear what you're trying to do with the radio ...

View answer
What are the EXACT rules about FCC vanity call sign assignments?
3 votes

Here is the most relevant section of 47 CFR: § 97.19 Application for a vanity call sign. (a) The person named in an operator/primary station license grant or in a club station license grant is ...

View answer
Can I use the dummy load provided with the nanoVNA for adjusting my QCX+
3 votes

I'm assuming your nanoVNA came with just a small SMA "terminator" load. I'm seeing various specs in various listings for various similar parts, but most of them are in the 0.5 to 4W range. ...

View answer
What would be the typical received power of an "S9" signal?
3 votes

The answer for a literal "S9" value is actually pretty simple! According to the table in this helpful article on S-meters, S9 corresponds to 50 picowatts of input power. This is actually by ...

View answer
How to safely connect a digital output to a receiver's antenna input?
3 votes

Looks like a 5V peak-to-peak sine wave into a 50 ohm load results in about 18 dBm of power (using my own Voltage to power converter and dBm ↔︎ watts converter tools so you might double-check the math)....

View answer
Why does path loss decrease as frequency decreases?
3 votes

This is actually a side effect from the receiver/transmitter gain terms in the overall equation! In short, as communication frequency gets lower, the antennas must grow bigger to keep the same gain. A ...

View answer