Most Popular
1500 questions
5
votes
3 answers
What do you call antenna that combines multiple Hustler resonators (using a VP-1) above a shared mast?
I know that a Hustler MO-3 54" mast with something like a RM-20S resonator on top is officially an example of a center-loaded quarter-wave vertical...
... but Hustler also allows you to mount multiple resonators (say, a RM20 or RM20S + RM30 + RM40…
Bitbang3r
- 401
- 2
- 9
5
votes
1 answer
can the adhesive used in thru-glass antenna couplers be replaced?
I recently bought a pair of self-adhesive thru-glass antenna couplers for my mobile radios and erred in mounting both of them, which required me to peel them off the side window glass in my minivan. The doublestick tape compound used on them…
niels nielsen
- 1,092
- 1
- 7
- 15
5
votes
5 answers
High-Z RF amplifier for magloop RX vs Q-factor
I've noticed that increasing load on magloop reduces it's Q-factor, it becomes less selective.
Traditional way to approach this is reducing size of pickup loop, or alternatively, using transformer.
But is it possible/known approach to build FET…
BarsMonster - R2AYN
- 406
- 1
- 3
- 15
5
votes
4 answers
Is an antenna always matched to free space impedance?
In this thesis the following model for an antenna is proposed:
It is seen as a 2 port network, in which only port 1 is accessible (port 2 is an imaginary connection between the antenna and the free space). Precisely:
$Z_0$ is the feed line…
Kinka-Byo
- 289
- 1
- 8
5
votes
2 answers
Receiving the ISS SSTV: dipole antenna configuration and orientation
In short
I am trying to receive SSTV Images from the ISS (145.8Mhz) and I all have is a simple "bunny ears" dipole antenna.
In what configuration (straight, vee shaped, upside down vee, ...) and orientation should I place the antenna to optimize…
Steven
- 205
- 2
- 6
5
votes
3 answers
Does Kirchhoff's current law (KCL) apply to antennas?
I think I'm having a hard time understanding HF antennas because they go against everything I've been taught about analyzing circuits.
If we look at a dipole antenna, there is the highest current in the middle and zero current at the ends. So if we…
Kenth Mirta
- 51
- 1
5
votes
2 answers
What are the steps to become an amateur operator in Canada?
A little background. My uncle devoted part of his late life to ham radio, he had his callsign and would go install/fix radio systems all the time,travel across the country and would teach newcomers and lived the ham radio way and I'm thinking of…
marc-andre benoit
- 153
- 3
5
votes
3 answers
SDR: How are I and Q determined from the incoming signal in quadrature sampling on the receiver side?
I'm new to digital radios and signal processing, so I apologize if this question is trivial but I haven't been able to find an answer here or by googling. Also, some terminology might be off, please feel free to refer me to correct sources or to…
Steven
- 205
- 2
- 6
5
votes
4 answers
Understanding how quadrature heterodyning captures information from negative frequencies
The way I understand how SDR works, there is a receiver input, generally connected to an antenna pulling in signals from the ether. That input is connected to two mixers (linear multipliers), being mixed with the same LO frequency in both mixers,…
KevinHJ
- 215
- 1
- 5
5
votes
2 answers
Calculating satellite passes without an internet tracker?
Situation:
You want to know when a satellite will pass in order to receive an image transmission or to work an amateur satellite. However, you cannot access internet for whatever reason, and therefore can't simply look up a pass prediction chart or…
Galaxy
- 199
- 2
- 14
5
votes
0 answers
What is an expected IF level of SA612?
I tried to use SA612 as a frequency mixer. Since it's a Gilbert cell, it has a high input impedance. Thus I added a pair of transformers as "Experimental Methods in RF Design" book suggests:
The mixer seems to work:
Here I'm using 15 Mhz 12 dBm LO…
Aleksander Alekseev - R2AUK
- 4,307
- 18
- 55
5
votes
3 answers
Design of oscillator
I'm looking for a good tutorial about oscillator design (electronically) for transmitter. The problems with current tutorials are almost all provide only schematics, some explain how it works. But noone show how we determine the transistor (select…
RainerJ
- 151
- 3
5
votes
3 answers
Why are contest signal reports always "59" or "599"?
I've heard lots of contest exchanges, and the signal report almost always seems to be 59 for phone or 599 for Morse, even when the operator giving the report has to request information to be repeated several times. Why is the signal report almost…
rclocher3
- 9,330
- 3
- 24
- 52
5
votes
3 answers
Characteristics of a "bad fist"?
What are some characteristics, when sending CW, of a "bad fist"? How bad can it get, typically, and still manage to communicate the message text sent to a human operator on the receiving end?
Contra-wise, what (slight?) variations from machine…
hotpaw2
- 13,635
- 8
- 49
- 83
5
votes
1 answer
What is the best frequency to start working EME on a budget?
Well, the title says it all: I want to start making EME contacts with the lowest possible budget, and I doubt between 2m, 70cm and 23cm. Since I cannot afford those expensive power amplifiers for these frequencies, I decided to go for a big yagi…
user3141592
- 276
- 2
- 9