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Questions tagged [components]

Questions about electronic components used in radio or antenna construction.

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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 ...
SRobertJames's user avatar
1 vote
1 answer
146 views

Why is my homebrew copper sulphate resistor behaving like a capacitor? [closed]

I brewed a CuSO4 resistor in a glass jar. I got the idea from here. This was done by creating a solution of Copper Sulphate in distilled water. The lid on the jar was provided with a BNC socket into ...
VU2NHW's user avatar
  • 2,834
1 vote
0 answers
66 views

Narrow bandstop filter not requiring ground connection in SMD package

I’m designing an antenna that I’ll implement on a printed circuit board. The antenna will be working on both sides of 900 MHz, so it’s not exactly for ham use. I’m planning to use a bandstop filter in ...
OH2FXN's user avatar
  • 968
3 votes
1 answer
439 views

Globar resistor repair or alternative(s)?

I am restoring a Hallicrafters S-120 receiver and when trying to unsolder the wires, from the electrolytic capacitor, I noticed that one of the terminals of the Globar resistor (880-100 Ohm / 023-...
essential555's user avatar
3 votes
1 answer
142 views

Tradeoffs: varicap vs. air variable capacitor for Rx bandpass?

What might be the tradeoffs between choosing varicap diodes versus air variable capacitors in the design and construction of tunable bandpass filters for HF receivers?
hotpaw2's user avatar
  • 13.5k
2 votes
1 answer
160 views

How to select capacitor for diplexer use

Follow-up on this question: How to prevent cracking the capacitors in my diplexer? Short story: 2m/70cm diplexer, to be used up to 50W. Schematic from Elsie: S21/S11: I don't know exactly what to ...
Dieter Vansteenwegen's user avatar
1 vote
0 answers
81 views

2GFSK digital filter bandwidth calculation

I'm working on a S2LP from ST and I am configuring the RX digital filter. I need to calculate the bandwidth of the signal which has 2GFSK modulation. Do you think the code below is correct for ...
Victor's user avatar
  • 111
5 votes
1 answer
188 views

How to prevent cracking the capacitors in my diplexer?

Just made my first 2m/70cm diplexer. Important: I aim to be able to use this up to 50 Watts. S21 from the LP section: Having access to regular distributors such as Farnell/Element14, Mouser, Digikey,...
Dieter Vansteenwegen's user avatar