Questions tagged [electronics]

Questions which involve the properties or applications of individual electronic components.

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9 votes
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Beyond Maximum Stable Gain of a transistor

I was plotting constant-gain circles on the Smith chart the other day for a potentially unstable RF transistor. I recently read on-line that for a potentially unstable transistor the maximum gain ...
Thomas L's user avatar
  • 193
6 votes
0 answers
388 views

How to estimate input and output impedance of an amplifier?

I'm trying to figure out how to design power amplifiers which input and output are properly matched to 50 Ohm. My thinking was that the most bullet proofed approach would be to model an amplifier in ...
Aleksander Alekseev - R2AUK's user avatar
5 votes
0 answers
887 views

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: ...
Aleksander Alekseev - R2AUK's user avatar
2 votes
0 answers
109 views

IF derived AGC: how to choose the best block diagram?

I've built several transceivers in the past. I never implemented IF derived AGC, so I decided to give it a try in the next project. I choose to build a superheterodyne receiver, which will probably ...
Aleksander Alekseev - R2AUK's user avatar
2 votes
0 answers
158 views

Diagnosing IC-7100 Drive Amp Bias | PA Won't TX

A faulty in vehicle DCDC charger has fed 16V or so into my brand new IC7100, killing the main board and preventing it from transmitting. I've replaced the mainboard with a brand new one however I'm ...
Alex Turner's user avatar
2 votes
0 answers
65 views

Clocking A and N in a Dual-modulus PLL Prescaler

In an effort to "up my game" attempting to build a VFO for my DIY transceiver, I've been looking at PLL theory and circuits. Many of my research references are quite old and I understand that many of ...
Buck8pe's user avatar
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2 votes
0 answers
165 views

What protocol does the Vertex VX-2200/2100 use for programming?

I have seen a number of programming cable schematics on the internet, but I couldn't understand very much how they worked. From what I picked from all schematics, it appears the protocol uses the <...
Ronan Paixão's user avatar
1 vote
0 answers
109 views

How do I test if three turns are better than 4 turns?

I built a class ab amplifier kit to use with my qrp radio. 2 watts in creates 50+ out. This was the pa 70 amplifier kit. It is a kit with no instructions, but a whole suite of internet videos and ...
Jeffrey Edward Messikian's user avatar
1 vote
0 answers
44 views

Is it beneficial to boost the transmit power from a transmitter past 2W around 2.4GHz?

I have a ready-made transmitter that outputs 2W of RF power at 2.4GHz carrier frequency (I'm trying to transmit TV using DVB-S2) into the antenna, and I was wondering if it made sense to add a power ...
user42875's user avatar
  • 151
1 vote
0 answers
58 views

Relay cross reference for 1925-3-2

My amateur radio uses 1925-3-2 relays on the low pass filter board to select bands. This relay is no longer available. Is there an alternative I can use? Or something?
Dave nf4r's user avatar
1 vote
0 answers
282 views

What will be antenna impedance of a dipole antenna when it is kept lambda/2 away from the transmitter

I understand that half-wave dipole antenna, which is in far-field, impedance is around 73 ohms. If I keep same antenna in near-fied at distnace lambda/2 from the 1.25 lambda length tranmiter?
Shiva Mudide's user avatar
0 votes
0 answers
35 views

Ferrites losses calculation

I am new on RF design. I would like to know more about ferrites. I am looking for information about how to calculate ferrite losses and saturation points for a given application. I also would like to ...
Drod's user avatar
  • 101