Hi Tony....
=20
The "beat" frequency is generally the difference (IF) frequency. In a
receiver the "beat frequency oscillator (BFO) is used to generate a
"beat" frequency in the audio range for CW reception. My copy of the
manual clearly states that the OSCILLATOR frequency is HIGHER than
the signal frequency on ALL bands.
=20
73, Roger

Well, I used the wrong term - beat frequency- due to my limited command =
of the English language.

In summary, what I am trying to say for the sake of justifying what I =
measure here is that the sentence "the oscillator frequency is always =
higher than the signal frequency" should have been more precisely =
written "the frequency used to convert the incoming RF signal to IF is =
always higher than that of the RF signal". In this way the sentence =
would become compatible with using the second harmonic of the oscillator =
for converting the RF signal (on 20 meters the measured fundamental =
oscillator frequency is lower than the RF signal, but its second =
harmonic is anyway higher).

Anyway, I agree with you that using the second harmonic of the =
oscillator is rather odd, but it is a fact that, in addition to the =
frequency meter and the oscilloscope measurement results, the phantom =
carriers coming from the 9.5 MHz band are exactly where they should be =
if the second oscillator harmonic is used.

It looks like a kind of a mistery. I hope that an SX101A owner will take =
care to measure the oscillator frequency at his first convenient =
occasion.

73

Tony, I0JX


the SX-101A, the frequency that converts the RF signal into the IF =
signal is always higher than the RF signal. This is absoultely true, on =
the other hand the receiver dial shows the same sense on all bands (if, =
on a certain band, the frequency that converts the RF signal into the IF =
signal would be lower than the RF signal, then the relevant dial would =
go in the opposite direction).

Agreed.

"Antonio Vernucci" wrote in message
...
Hi Tony....

The "beat" frequency is generally the difference (IF) frequency. In a
receiver the "beat frequency oscillator (BFO) is used to generate a
"beat" frequency in the audio range for CW reception. My copy of the
manual clearly states that the OSCILLATOR frequency is HIGHER than
the signal frequency on ALL bands.

73, Roger

Well, I used the wrong term - beat frequency- due to my limited command of
the English language.

In summary, what I am trying to say for the sake of justifying what I
measure here is that the sentence "the oscillator frequency is always higher
than the signal frequency" should have been more precisely written "the
frequency used to convert the incoming RF signal to IF is always higher than
that of the RF signal". In this way the sentence would become compatible
with using the second harmonic of the oscillator for converting the RF
signal (on 20 meters the measured fundamental oscillator frequency is lower
than the RF signal, but its second harmonic is anyway higher).

Anyway, I agree with you that using the second harmonic of the oscillator is
rather odd

[SNIP]

Oh, I don't know. The Heath HR-10 ham receiver, while admittedly in a lesser
league, did this on 15 and 10 meters and admitted it. I would strongly
suspect that many of the lower end sets did this, but didn't fess-up.

[SNIP]
=20
Oh, I don't know. The Heath HR-10 ham receiver, while admittedly in a =
lesser=20
league, did this on 15 and 10 meters and admitted it. I would strongly =

suspect that many of the lower end sets did this, but didn't fess-up.=20
=20

I am not sure of their rationale. Perhaps the stability of 30 MHz =
oscillator is, in practice, more than twice worse than that of a 15 MHz =
oscillator, so they preferred to work at lower frequency and take the =
second harmonic. They did not even care to filter the oscillator =
frequency so as to remove the fundamental and leave only the harmonic.

By the way I put a parallel LC circuit in series with the 20 meter RF =
input transformers, and, adjusting its for resonance around 9.6 MHz, the =
BCs disappear completely. Adjustment is quite critical and the resulting =
BCs attenuation is tremendously high.

73

Tony I0JX / K0JX