How to count the numbers of tuned circuits
ID: 41559
How to count the numbers of tuned circuits
24.Jan.05 18:03
0
Hello all radio friends,
when uploading a new model, it is possible to enter the number of tuned circuits, but I don't know how to count them.
Is it only the tuned circuits that help to determine the selectivity of a receiver (antenna and Intermediate frequency stages) or does one count also the oscillator tuning circuit?
What about the receivers with several bands? Do you count for each band the antenna and the oscillator tuning circuits?
Please clarify?
when uploading a new model, it is possible to enter the number of tuned circuits, but I don't know how to count them.
Is it only the tuned circuits that help to determine the selectivity of a receiver (antenna and Intermediate frequency stages) or does one count also the oscillator tuning circuit?
What about the receivers with several bands? Do you count for each band the antenna and the oscillator tuning circuits?
Please clarify?
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Number of tuned circuits
24.Jan.05 21:24
Hello Georges,
usually the number of active circuits is considered:
preselection/antenna (1 or sometimes 2); in case of an RF stage the interstage circuit, and the oscillator (all of them are variable). Easiest is to count the gang condenser sections.
Plus the fixed IF circuits, mostly band filters (2, sometimes 3 or even 4 circuits in a filter).
Inactive coils like other band coils do not count (besides that: they are not circuits, lacking the tuning capacitor if not selected).
Of course: in AM the FM filters do not count and vice versa.
I hope this might help You.
Regards
KoBi
usually the number of active circuits is considered:
preselection/antenna (1 or sometimes 2); in case of an RF stage the interstage circuit, and the oscillator (all of them are variable). Easiest is to count the gang condenser sections.
Plus the fixed IF circuits, mostly band filters (2, sometimes 3 or even 4 circuits in a filter).
Inactive coils like other band coils do not count (besides that: they are not circuits, lacking the tuning capacitor if not selected).
Of course: in AM the FM filters do not count and vice versa.
I hope this might help You.
Regards
KoBi
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25.Jan.05 12:17
Thank you, Konrad.
As I understand, this figure is meant as a kind of relative quality mark to distinguish the performance
of receivers and to be able to compare them.
But if you specify this, shouldn't is be advisable to mention also the wave band where they are active? i.e. MW?
And what about the IF stop filters (a tuned serial or parallel circuit, avoiding to enter IF frequencies in the receiver)?
Best regards
As I understand, this figure is meant as a kind of relative quality mark to distinguish the performance
of receivers and to be able to compare them.
But if you specify this, shouldn't is be advisable to mention also the wave band where they are active? i.e. MW?
And what about the IF stop filters (a tuned serial or parallel circuit, avoiding to enter IF frequencies in the receiver)?
Best regards
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Broadcast receivers and circuits
25.Jan.05 12:27
You are correct:
Normally you find 6 circuits on a "normal Superhet". If it has seben it will perform much better. For normal "broadcast receivers" this is also true for all AM bands. If not there will be remarks in the notes.
Circuits for FM you find as well if aplacable.
I asked Konrad to give some examples and make clear that a normal IF filter consists of 2 circuits (can have more). Such circuits to stop the IF from or to the antenna do not help the selection and therefore are not counted for. One could now argue that this is the case for the oscillator too ... But it is international custom to count this one too.
Normally you find 6 circuits on a "normal Superhet". If it has seben it will perform much better. For normal "broadcast receivers" this is also true for all AM bands. If not there will be remarks in the notes.
Circuits for FM you find as well if aplacable.
I asked Konrad to give some examples and make clear that a normal IF filter consists of 2 circuits (can have more). Such circuits to stop the IF from or to the antenna do not help the selection and therefore are not counted for. One could now argue that this is the case for the oscillator too ... But it is international custom to count this one too.
To thank the Author because you find the post helpful or well done.
tuned circuits count
25.Jan.05 13:07
Well, I think for the purpose of coarse comparison we should limit such data to general figures.
As there are 3- and 4- circuit IF-filters (variable bandwidth) they only serve one single IF stage, while two "ordinary" band filters belong to two stages. That makes a lot of difference in terms of amplification/senitivity.
I know there are special cases, e.g. Zenith Transoceanic 7-G-605, where the number of tuned circuits in SW is less than that in BC.That is also common in communication receivers, where dual or triple conversion is selected depending on the waveband.
Such particularities may find place in the remarks.
IF stop circuits and wave traps do not count.
As there are 3- and 4- circuit IF-filters (variable bandwidth) they only serve one single IF stage, while two "ordinary" band filters belong to two stages. That makes a lot of difference in terms of amplification/senitivity.
I know there are special cases, e.g. Zenith Transoceanic 7-G-605, where the number of tuned circuits in SW is less than that in BC.That is also common in communication receivers, where dual or triple conversion is selected depending on the waveband.
Such particularities may find place in the remarks.
IF stop circuits and wave traps do not count.
To thank the Author because you find the post helpful or well done.