Questions tagged [equipment-design]
The equipment-design tag has no summary.
96 questions
1
vote
1
answer
81
views
USDX+ , FT-8 and cables to connect to a a soundcard
I have a USDX+ rig I want to connect to a soundcard with microphone input (MIC/ KEY) and earphone (HP output) output to use with FT-8. I need to adapt the levels from the hp output to the values ...
- 111
1
vote
1
answer
164
views
Quartz Oscillation Output Signal Amplifying for more Power?
Quartz oscillation is well known for its high Q-Factor and stable frequency. I have read many articles which say that amplifying such quartz oscillations should not be easy. I am not a licensed radio ...
user24106
6
votes
4
answers
1k
views
Why do homebrew designs wrap toroids instead of using off the shelf inductors?
Why do homebrew designs wrap toroids instead of using off the shelf inductors?
Off the shelf inductors are easily available in a range of values, including uH and even some mH. And hand wrapping ...
- 301
2
votes
1
answer
174
views
How can I key low voltage and still keep a tube VFO running constantly?
I'm interested in building a VFO based single tube CW transmitter.
These devices are known to have issues with frequency drift and chirp; frequency drift can apparently be mitigated by ensuring ...
- 4,146
0
votes
1
answer
131
views
Given that transmit "chirp" is mainly thermal related, what parts would need to be temperature regulated to limit chirp?
I'd like to build a Colpitts (or Hartley) oscillator based one-tube CW transmitter, and I'd like to use a VFO circuit rather than crystal control (in part because of the expense and limited ...
- 4,146
1
vote
1
answer
2k
views
Need some help to design a DIY MW Radio receiver
AM Medium Wave Radio Receiver Design.
First of all, I am a hobbyist and stuff related to electronics are not very strange to me but the chapter of Radio and RF frequency , intermediate frequencies , ...
- 53
3
votes
1
answer
188
views
How do I couple two VHF Small Signal Amplifiers together?
I have managed to build single stage VHF amps ok using the transistor's S-Parameters to determine the load and source reflection coefficients for a specific gain and stability considerations.
Simple ...
- 191
2
votes
1
answer
378
views
Connect mobile device with coax cable to SDR board
My goal is to connect mobile devices using a coax cable with a SDR board to be independent from using the air interface and antennas. I don't know how to connect my devices with the SDRs since I'm an ...
- 123
0
votes
1
answer
299
views
How to create FM Radio Mesh
What (devices transmitters, receivers and transceiver) do i need to create a fm radio mesh, instead of using a single transmitter with big antenna, i want to build fm transceiver mesh radio to cover ...
1
vote
2
answers
396
views
Is a 94' dipole antenna fed directly by coax useful for any particular known purpose?
I'm trying to figure out an old handmade antenna I picked up at a swap meet a few years back. It is a dipole (or "doublet"?) that is both made of coax but also fed by a length of built in ...
- 7,579
5
votes
2
answers
5k
views
Why do Baofeng radios have such poor reception reliability?
What is the nature of Baofeng radios' poor receiver performance?
This brand of handhelds has somewhat notoriously poor receivers. I hadn't noticed this much when using them for short distance simplex ...
- 7,579
1
vote
1
answer
959
views
Help understanding Kenwood AT-230 tuner topology
Can you help me understand what the topology of my Kenwood antenna tuner is trying to do and what it might be compared to?
Below is the schematic of my Kenwood AT-230 antenna tuner, and below that ...
- 113
7
votes
1
answer
1k
views
Why would a VNA not make a good Spectrum Analyzer? Or an SDR a good VNA?
Happy to be corrected where I'm wrong in any of this but in broad strokes my understanding is:
Spectrum Analyzer
measures input signal strength while sweeping across frequencies, measuring RF ...
- 7,579
1
vote
1
answer
176
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 ...
- 301
3
votes
2
answers
416
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 ...
- 160