Hi Group,

I am looking at moving the old CB up to 10meter CW/SSB, One thing I
have never seen is the addition of a BFO circuit to copy SSB and CW.

The radio has a first IF of 10.695 MHz and the next one is 455KHz.

I believe that 455KHz is the place to add the BFO and I think that the
455KHz IF must be mixed with another frequency, say either +/- 1KHz to
get the sidetone.

I don't know if this would work for SSB reception?

How about Double-side band modulation, it would have both LSB and USB
but at least it would be interesting to experiment with.

If you know of a circuit or article, please post.

I look forward to your posting.

Paul
KJ4UO
EM60

E-mail me directly and I will send you a schematic of an NE602 based
detector circuit in PDF form.

Pete

wrote in message
oups.com...
Hi Group,

I am looking at moving the old CB up to 10meter CW/SSB, One thing I
have never seen is the addition of a BFO circuit to copy SSB and CW.

The radio has a first IF of 10.695 MHz and the next one is 455KHz.

I believe that 455KHz is the place to add the BFO and I think that the
455KHz IF must be mixed with another frequency, say either +/- 1KHz to
get the sidetone.

I don't know if this would work for SSB reception?

How about Double-side band modulation, it would have both LSB and USB
but at least it would be interesting to experiment with.

If you know of a circuit or article, please post.

I look forward to your posting.

Paul
KJ4UO
EM60

Hi Paul:
For better help, I whises known your detector in actual rig.-
It is transistor o valve? The BFO can be a oscilator within IF coil in clapp
or hartley layout.-
REgards
Heriberto

escribió en el mensaje
oups.com...
Hi Group,

I am looking at moving the old CB up to 10meter CW/SSB, One thing I
have never seen is the addition of a BFO circuit to copy SSB and CW.

The radio has a first IF of 10.695 MHz and the next one is 455KHz.

I believe that 455KHz is the place to add the BFO and I think that the
455KHz IF must be mixed with another frequency, say either +/- 1KHz to
get the sidetone.

I don't know if this would work for SSB reception?

How about Double-side band modulation, it would have both LSB and USB
but at least it would be interesting to experiment with.

If you know of a circuit or article, please post.

I look forward to your posting.

Paul
KJ4UO
EM60

wrote in message
oups.com...
Hi Group,

I am looking at moving the old CB up to 10meter CW/SSB, One thing I
have never seen is the addition of a BFO circuit to copy SSB and CW.

The radio has a first IF of 10.695 MHz and the next one is 455KHz.

I believe that 455KHz is the place to add the BFO and I think that the
455KHz IF must be mixed with another frequency, say either +/- 1KHz to
get the sidetone.

I don't know if this would work for SSB reception?

YOu can build a BFO for either one of three frequencies.
1. Near the input signal
2. Near 455 khz
3. near 10.695

It will almost have to be variatable as the CB rig will be crystal controled
and unless it has a fine tuning control (most of the AM units did not ).

wrote:

Hi Paul

I am looking at moving the old CB up to 10meter CW/SSB, One thing I
have never seen is the addition of a BFO circuit to copy SSB and CW.

If you have an AM CB you will be able to receive DSB by the addition of
a BFO. It might work for sending CW, since it is an unmodulated carrier
afterall (some 10m beacons are recycled CB RTXes). You won't be able to
transmit SSB, though!

The radio has a first IF of 10.695 MHz and the next one is 455KHz.

I believe that 455KHz is the place to add the BFO and I think that the
455KHz IF must be mixed with another frequency, say either +/- 1KHz to
get the sidetone.

Correct. You need to inject a 455kHz into the second conversion mixer.
You don't necessarily need to phisically connect it to the circuitry,
over-the-air coupling should suffice.

I don't know if this would work for SSB reception?

Sure it does! (provided your starting point has AM reception).
See my pages http://spazioinwind.libero.it/ik1zyw...re/osc455.html
and http://spazioinwind.libero.it/ik1zyw...c455notes.html for
some operating notes. Please disregard the circuit shown since there are
better solutions.

How about Double-side band modulation, it would have both LSB and USB
but at least it would be interesting to experiment with.

With an external BFO you'll be actually receiving DSB, so no
discrimination between U and LSB. CW stations will appear twice as you
tune up the band. Anyway, since 10m at this time of the solar cycle are
not too crowded (from the European point of view), you should not suffer
opposite sideband interference from off-frequency stations. Making the
BFO frequency agile should overcome your channelized CB limitations.

I haven't been playing with this setup for a while, but it works.

73,
Paolo/Paul IK1ZYW

wrote:
Hi Group,

I am looking at moving the old CB up to 10meter CW/SSB, One thing I
have never seen is the addition of a BFO circuit to copy SSB and CW.

The radio has a first IF of 10.695 MHz and the next one is 455KHz.

I believe that 455KHz is the place to add the BFO and I think that the
455KHz IF must be mixed with another frequency, say either +/- 1KHz to
get the sidetone.

I don't know if this would work for SSB reception?

How about Double-side band modulation, it would have both LSB and USB
but at least it would be interesting to experiment with.

If you know of a circuit or article, please post.

I look forward to your posting.

Paul
KJ4UO
EM60

Why would you want to re-invent the wheel !!!

There are millions of old 40 channel AM/SSB Cb sets available that are
easily convertable to Ten Meters with a exacto knife and a bit of solder

IS THIS A TROLL !!!

Yukio YANO

In article 4WyFe.45555$5V4.41179@pd7tw3no, Yukio YANO wrote:
wrote:

I am looking at moving the old CB up to 10meter CW/SSB, One thing I
have never seen is the addition of a BFO circuit to copy SSB and CW.

Why would you want to re-invent the wheel !!!

There are millions of old 40 channel AM/SSB Cb sets available that are
easily convertable to Ten Meters with a exacto knife and a bit of solder

Possibly he's interested in it precisely because of the
experimentation and learning required? Because it might increase his
own understanding and skill level, as a result of figuring out how to
do it?

That is, after all, one of the justifications for amateur radio here
in the U.S.!

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Hi there Paul,

I took a look, the circuit looks good, so why the better method
comment?

If this 455KHz injected "over the air" signal is captured by the
receiver, should the s-meter provide a constant signal level?

If the SSB signal is coming in strong (S9), and the captured BFO level
is S3, will the amplitude of the BFO have to be increased?

How about AGC on the BFO so that its injection level is a function of
signal level?

Thanks again for the information!

wrote:

'morning

I took a look, the circuit looks good, so why the better method
comment?

Well, at that time I wanted to experiment how ceramic filters worked, so
I built a very low frequency oscillator and filtered out the wanted
signal near 455k. There is also a slight overhead using just 1/6th of a
TTL chip!

Subsequent studies and experiments taught me that an RC oscillator can
be sufficiently stable at those frequencies. I believe a 455k RC
oscillator can be built right away.

If this 455KHz injected "over the air" signal is captured by the
receiver, should the s-meter provide a constant signal level?

I experimented the external BFO only on those cheap multiband SW radios,
and they have no s-meter.

Moreover I am personally not too interested in meter reading unless I am
measuring something (ie difference between two signals). I prefer to
evaluate a signal by ear.

If you need/want to rely on meter readings, remember that an additional
BFO will give you AM-DSB, while you'll be listening to a SSB signal.
That's half power, the meter should read 3dB less than actual strength
(half point?!).

If the SSB signal is coming in strong (S9), and the captured BFO level
is S3, will the amplitude of the BFO have to be increased?

I do not remember having to deal with BFO amplitude. In "complex"
receivers there might be some implications with AGC, especially if it
follows the 455k mixer (doubt so, it is probably after the 1st conversion).
Assuming the AGC on the 1st IF, then the 455k IF signal level is rather
constant, so BFO amplitude should not need adjustments.

How about AGC on the BFO so that its injection level is a function of
signal level?

That is becoming too complex for a simple solution, IMHO. :-)


Let us know how you decided to proceed and how it worked.

Greetings from the other side of the Atlantic (and a bit of
Mediterranean as well),
Paolo IK1ZYW

Hi Paul:
When BFO is used, then AGC should be derived from audio signal,
not a If signal.-
REgards
Heriberto -
escribió en el mensaje
oups.com...
Hi there Paul,

I took a look, the circuit looks good, so why the better method
comment?

If this 455KHz injected "over the air" signal is captured by the
receiver, should the s-meter provide a constant signal level?

If the SSB signal is coming in strong (S9), and the captured BFO level
is S3, will the amplitude of the BFO have to be increased?

How about AGC on the BFO so that its injection level is a function of
signal level?

Thanks again for the information!