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2
votes
3answers
50 views

Explanation of VFO as one part of the the tuning variables in mixers

I do apologize if this has been answer previously, but the term "VFO" seems to have become overloaded over the years. I think I have a handle on the notion of multiple VFOs on device for the ...
0
votes
0answers
28 views

Why hot to brass and nutral to silver on electrical connections? [closed]

Is it something to do with electrolysis?
4
votes
2answers
72 views

Power rating of a selfmade air coil

A colleague was winding an air coil himself. It's a 110µH coil with 200 windings for an 80m antenna, intended to be used on a 600 W transceiver. He used a copper lacquer wire with 0.6mm diameter. ...
0
votes
1answer
54 views

AM radio cross-talk / hearing strong station everywhere

I've built the M0AYF active loop antenna for my RTL-SDR, using BC847C for the amplifier transistors. There are a couple very strong AM stations here, usually playing music. What I'm noticing is that ...
1
vote
1answer
42 views

Current Transformers in Series versus a Single Voltage Transformer

I've read that the commonly used 49:1 (7t:2t) auto transformer for Multi-band End-fed Half-wave (EFHW) antennas has criticisms as not being very efficient. I haven't found any other designs that ...
0
votes
0answers
36 views

Weird looking spectrum. FSK and ASK combo?

Does this look familiar to anyone ?
3
votes
2answers
64 views

VHF Balancing, necessary? Methods?

This is a question about power dissipated due to radiation and ohmic heating caused by common mode current in the coaxial shielding, specifically at VHF frequencies. When a balanced antenna (such as a ...
2
votes
2answers
53 views

How to hang a balun at the center of a lightweight antenna?

I built my first 1:1 CMC transformer recently using 100 ohm CAT5e pairs in parallel. I used an FT-114-43 with 9 turns on each side and squeezed it into a small box with female coax connectors. I plan ...
5
votes
2answers
86 views

Eliminating RFI from raspberry pi

I am trying to eliminate RFI coming from a raspberry pi 4. The Rtlsdr(enclosed in a metal case) is directly plugged into the pi without any USB extension cable. The frequency of interest is at 1420....
0
votes
0answers
21 views

Would it be possible to receive the transmissions from JWST as an amateur? [migrated]

Would it be possible to receive the transmissions from JWST (James Webb Space Telescope) as an amateur, building your own antena? Would the transmissions be encrypted? One source cites it using: S-...
1
vote
0answers
26 views

S-Parameters Power amplifier impedance matching

I recently decided to conceive a 10W class 446MHz amplifier. I want to be able to amplify a 100mW signal into a 10W, for that i'm going for a two stages amplifier : SKY65162 to amplify the signal to ...
1
vote
0answers
22 views

What's a good choice of antenna tuners, if I add a 800 watt amp to my station [closed]

I am running a barefoot 100 watt radio for my HF operations now. Also using a MFJ tuner that's limit is 300 watts. I am putting on my wish list a 800 watt amp. So I know I will have to upgrade my ...
6
votes
1answer
378 views

Yaesu VX-7R clock is running very fast

I just noticed the clock on my Yaesu VX-7R is running very fast. I noticed this a few days ago, where it would be days ahead. I would reset the time to the second and then, again, hours or days ahead. ...
0
votes
2answers
50 views

SMA 3.5mm to Baofeng or similar radio

My friend just got a 2006 Chevy Calorado and it came installed with an 3.5mm SMA cable running from the roof to under the dash. It was a park ranger vehicle so it would make sense that they needed a ...
2
votes
1answer
64 views

Performance gain when turning off CTCSS/DCS?

By turning of CTCSS/DCS can there be an increase in performance*? *Performance: Battery life Latency Range Voice quality From what I understand CTCSS/DCS is extra work for the IC inside the radio. ...
1
vote
1answer
46 views

What are the limitations of the 6.765 - 6.975 MHz ISM band in the United States? [closed]

There is a region of the lower 43 meter band designated for ISM use in the United States by the FCC starting at 6.765 MHz and ending at 6.975 MHz. Both "FIXED" and "MOBILE" usage ...
3
votes
0answers
29 views

Radio Service Software Motorola Syntor x9000

My name is Roger, I live in Sweden, have bought some old motorola synths x9000 transceivers that I need to reprogram, but have great difficulty finding the Rvn 4007E software as it should be. Have ...
6
votes
1answer
109 views

Can we use UHF/VHF ham bands for search and rescue missions?

Suppose that several licensed amateurs are part of a volunteer search and rescue team. The team is normally licensed and carries equipment to communicate on a variety of public safety bands in VHF/UHF ...
1
vote
0answers
32 views

Grounding an Inverter, good or bad if also plugged into a grounded AC Outlet? [closed]

If you have an DC/AC Inverter with a AC Transfer switch (so it also connects to grid power AC/110V to pull power from the grid when/if the 12V battery source drains down), and the inverter ...
1
vote
1answer
69 views

Can you think of any reason my NanoVNA says my antenna has 1.2 SWR while my radio says it has off the scale SWR?

My radio is an mcHF kit that I just finished soldering up. It receives fine, but when I went to transmit it's giving off the scale SWR. I rechecked my antenna with my NanoVNA, and it shows 1.2 SWR at ...
2
votes
1answer
51 views

Is there value in grounding the virtual null in an auto transformer?

I've been learning how to make 49:1 auto transformers to run end fed half wave antennas. As I understand it, the twisted lead forms a zero voltage point which acts like a ground. Assume I'm using ...
13
votes
1answer
1k views

Hanging a dipole from a tree not code compliant?

I just got off the phone with my town's electrical inspector (in Massachusetts), and he informed me that you are not allowed to hang anything electrical from "vegetation". He said if I did ...
1
vote
0answers
36 views

what frequencies are used for wireless remote control of hearing aids? [closed]

I have a pair of hearing aids which can be toggled between listening modes (telephone, noisy room, outdoors, etc.) using a key fob-like device. The control fob was lost before I got the aids, so I ...
3
votes
1answer
64 views

Zigzag line on CB band

I'm seeing this strange signal on the CB band around 27 MHz, at a glance it looks similar to NFM modulation, but it's just noise when tuned to. It's transmitted about every minute. My setup is RTL-SDR ...
0
votes
0answers
23 views

Baofeng UV-9R Software Trouble

I have CHIRP daily-20220103 It works great on my Baofeng BF-F8HP. When I load the Baofeng UV-9R I cannot go to the settings tab. I can get to the memories tab just fine. I decided to load the software ...
11
votes
4answers
4k views

Hearing Morse code after end of session?

Does anybody still hear phantom Morse code in your brain after ending a session? I'm hearing random beeps that definitely don't come from an external source. I tried to search Google but couldn't find ...
0
votes
2answers
90 views

How to run chirp with python3-based system (workaround found now)

Has anyone been successful getting chirp to run on a Linux system that's primarily set up for Python3? I find it's complaining about not finding the serial module, but when I install it with pip (...
1
vote
0answers
110 views

Need help in the fabrication of an UHF power amplifier

I recently decided to conceive a 10W class 446MHz amplifier. I want to be able to amplify a 100mW signal into a 10W, for that i'm going for a two stages amplifier : SKY65162 to amplify the signal to ...
0
votes
1answer
29 views

Can Direwolf be used with existing amateur packet radio satellites?

I've had an interest in amateur packet radio for a long time, specifically working amateur packet radio satellites, and specifically the ISS digipeater. In my journey through to the infinitely ...
2
votes
2answers
77 views

How do you calculate peak voltage given VSWR caused by impedance mismatch in a 50-ohm system?

I would like to choose a feedline that is safe for the wattage at a given VSWR to avoid coax arcing. How do you calculate peak voltage given a peak power in watts and maximum expected VSWR from ...
1
vote
2answers
34 views

GS cards in NEC decks

I'm trying to understand the use of GS cards in NEC2 decks. The documentation is rather vague! Consider a basic stack: ...
0
votes
3answers
84 views

How to transmit computer audio to a wireless microphone receiver? [closed]

I'm currently trying to broadcast my computer's audio output to a wireless microphone system receiver so that I can accompany my school's coming presentation with music. The frequency range is 480-598 ...
1
vote
1answer
69 views

FCC Guidelines for Radar

I'm working on some research for a project of mine. The project requires the use of millimeter wave radar. I am having a very hard time figuring out what the FCC's regulations on frequencies and ...
-2
votes
1answer
43 views

Baofeng F8HP display setup

On the Baofeng F8HP display, which bottom or top is the RX and TX?
2
votes
2answers
76 views

What's the difference between LPF and BPF in context of bandwidth setting?

I'm used to simple RX/TX bandwidth configurations, on my VHF FM rig it's either narrow, normal, or wide. It seems to be much more complex on my new HF SDR rig, and the instructions don't say anything ...
2
votes
1answer
49 views

Parameters needed to calculate inductor value to achieve proper phase delay?

I'm thinking about trying a coil in my collinear 5/8λ antenna, instead of the 3/8λ phasing delay line between the lower and upper elements pictured below. I figure that a coil with a certain ...
1
vote
1answer
81 views

Is SSB and FM voice considered TDD or FDD (and what are TDD/FDD)?

We are looking at the Qorvo QPL9547 LNA and the datasheet notes: For TDD Applications: R1 = 0Ω & R2 = 100K For FDD Applications: R2 = 100K ‘OR’ Pin 6 tied to ground. R1 = DNP/Omitted This will ...
2
votes
2answers
113 views

What safety procedures should be followed when developing and testing a high power amp?

I'm designing a 300W power amplifier using the MRF300AN from NXP targeting a center frequency of 146 MHz. Obviously I need to keep my fingers out of it and test into a dummy load, but generally ...
2
votes
1answer
27 views

Whip/stub antenna sorting with SA using VSWR

I have an assortment of whip antennas for various RX & HT devices such as a 2M/70cm FT740, a Uniden race scanner 29-54Mhz/108-174Mhz/406-470Mhz/806-956Mhz, a similar Realistic Pro-32 scanner and ...
1
vote
1answer
48 views

the transmission and reception block for the hackRF does not work Windows 11

Previously, I used the "Osmocom sink" and "Osmocom Source" blocks, but after updating the GNU radio to version 3.9.4, these blocks were gone. As far as I understand, now it has ...
3
votes
4answers
700 views

Why am I hearing FM radio show content on 1.355 MHz? (Using CubicSDR and SDR kit)

I am just beginning to learn about SDR. I purchased a "NooElec NESDR Mini 2 SDR & DVB-T USB Stick (RTL2832 + R820T2) with Antenna and Remote Control" I plugged it into my Mac, downloaded ...
4
votes
5answers
161 views

Antenna grounding / bonding in relation to my AC service (with pictures)

I'm trying to figure out how to properly connect new ground rods for an antenna to my main panel. Any advice from those who have done this + have great electrical knowledge would be greatly ...
2
votes
1answer
94 views

How do businesses develop and test amateur radio products in the US if you cannot be paid for amateur radio use?

Certainly there are companies in the US (like Kenwood) that develop HAM products that transmit. For development and QA they would likely need to test the product outside of a Faraday cage. How can ...
0
votes
2answers
70 views

Help setting up my uv-5r radio [closed]

I am a disabled person and need help programming my uv-5r with all the pertinent emergency frequencies that apply to my area. Aurora, colorado. I'm not licensed ham and want to stay within the legal ...
7
votes
6answers
7k views

Why is 20m band waterfall showing signals every 50 kHz?

I'm very new to shortwave listening and just got to grips with my RTL SDR HF dongle. Last night while on the 20m band, there were signals exactly every 50kHz, starting exactly at 14.000MHz, then at 14....
5
votes
3answers
133 views

Which way is a yagi polarized?

I am installing a yagi antenna that will receive signals from multiple omni antennas that are vertically polarized. Which way should the elements of the yagi point to match? Up and down, or horizontal?...
3
votes
1answer
95 views

How to balance a mixer?

I have read about double-balanced mixers and as far as I got the theory right they should suppress carrier frequency. I am trying to build my own transceiver project and I cannot suppress the carrier. ...
4
votes
2answers
101 views

Can I use my CB mobile antenna with a 10 meter radio also?

I have a mobile mounted CB antenna that has an SWR of 1.5 on channel 20. Is it possible to use it with a 10 meter radio? I do not have enough room on my car for an additional antenna, so if it is ...
0
votes
0answers
16 views

Need Help Setting up TS/CC's on XPR8300 Talk Groups

New Motorola XPR8300 repeater in place, but NO idea how to set up Talk Groups. HELP! Tommy NH7R
1
vote
1answer
55 views

Can Baofeng UV-5R HTQ scan and handle TDR (split) mode at the same time?

Today I received my first radiotelephone, Baofeng UV-5R HTQ. I saved some frequences and put the device in the MR mode. In one frequency, I make it scan through the saved frequencies, on the other one ...

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