7
votes
Accepted
How to reduce VFO sensitivity to the hand capacitance?
As mentioned in the comment by henryflower, make sure that the shaft (and thus the frame) of the variable capacitor are grounded.
You need to use rubber mounting grommets around the screws which bolt ...
- 3,739
5
votes
What is the use of dual VFOs?
Dual VFOs are needed for transmitting on one frequency but listening on another. The reason why this is done is nicely explained here.
This is called operating "split" and it takes a ...
- 8,174
4
votes
How to reduce VFO sensitivity to the hand capacitance?
Circuit looks OK.
Note that the highest impedance point in this circuit is near the box open end. RF voltage here is highest in this oscillator, and is susceptible to coupling out the top.
A shield ...
- 1,219
4
votes
What is the difference between RIT and XIT?
Modern radios that have RIT and XIT typically also have a button that you can use to listen on your transmit frequency. This means that if you use XIT or RIT, then you can listen on your transmit ...
- 4,669
3
votes
Swan 350 calibration
Is their a way to get the vfo calibrated without the use of a a frequency counter?
There certainly is! We use the US and Canadian government's standard frequency radio stations. See this question and ...
- 8,174
3
votes
Explanation of VFO as one part of the the tuning variables in mixers
The more general term is LO - the Local Oscillator that goes into one side of every mixer.
In analogue radio you will have several (very different) LOs used to mix the signal down from RF to where you ...
- 12.2k
3
votes
What is the difference between RIT and XIT?
RIT means that your VFO frequency will be offset from your dial frequency (usually by a relatively small amount) while you are receiving. XIT means that your VFO frequency will be offset from your ...
- 13.2k
3
votes
What is the use of dual VFOs?
For anyone new to ham radio: in the analog era, in order to listen on one frequency and transmit on another with a single HF receiver or transceiver, by flipping a switch rather than turning a knob I ...
- 9,320
3
votes
How to convert a crystal controlled tranceiver to VFO (aka Unbinding from the Rock)?
I'd frankly not replace the crystal with an oscillating circuit of adjustable resonance frequency, like you're recommending, but the whole oscillator: remove (the unlabeled) C3, and just insert the ...
- 17.4k
2
votes
What is the difference between RIT and XIT?
While most modern radios are vary accurate in regards to frequency, not all radios are. Our signals get garbled with the transmitting frequency of one radio is not the same as the receiving frequency ...
- 1,854
2
votes
Accepted
How to convert a crystal controlled tranceiver to VFO (aka Unbinding from the Rock)?
The Heathkit HW-7 offered the option of crystal or VFO control via front-panel pushbutton switch. Pierce crystal oscillator Q5 was repurposed as a buffer amplifier for use with a VFO by switching out ...
- 7,912
2
votes
What is the use of dual VFOs?
Many radios will have buttons labeled "VFO1" and "VFO2", suggesting there are two oscillators when actually there is only 1. The buttons simply store a frequency in memory which is ...
- 52.5k
2
votes
Accepted
How to handle old stuck tuning slugs?
You should never use a metal tool on powdered iron or ferrite tuning slugs, adjustment tools for them are usually some type of plastic. You should be able to find these online. The better the fit, the ...
- 252
1
vote
Accepted
Explanation of VFO as one part of the the tuning variables in mixers
There are many kinds of radio receiver architectures, but a very common one is a superheterodyne, or "superhet". In a superhet, the tuned frequency can be the sum (or difference) of ...
- 13.6k
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