Foxx-3

[Camerart]

Hi all,

I've just completed a FOXX-3 radio kit. 40MTR 1W 12V.

I've played with crystal sets, many years ago, when I would try a
million set-ups for aerial and earth, but now i would like to be a bit
more precise.

I've made an aerial somewhere near the suggested ideas (end feed 1/2
wave), but on switching on. I don't get any signal from the earphone.

What I would like to know is, should any aerial work, just to find out
if the radio works, or if the aerial is out of tune, will there be no
signal.

Cheers, Camerart.




--
Camerart

[Ralph Mowery]

"Camerart" <Camerart...@radiobanter.com> wrote in message
news:Camerart...@radiobanter.com...

On 40 meters just about any wire more than 20 feet long outside should bring
lots of signals. For receive only, you could just stick a 20 foot or longer
wire in the antenna jack and hear something unless you are inside a
building that has lots of material that radio waves will not penetrate.

If you have an antenna up that is even within 50% of being intune it should
receive lots of signals.

[Camerart]

Ralph Mowery;798263 Wrote:
> "Camerart" Camerart...@radiobanter.com wrote in message

> news:Camerart...@radiobanter.com...-

>
> Hi all,
>
> I've just completed a FOXX-3 radio kit. 40MTR 1W 12V.
>
> I've played with crystal sets, many years ago, when I would try a
> million set-ups for aerial and earth, but now i would like to be a bit
> more precise.
>
> I've made an aerial somewhere near the suggested ideas (end feed 1/2
> wave), but on switching on. I don't get any signal from the earphone.
>
> What I would like to know is, should any aerial work, just to find out
> if the radio works, or if the aerial is out of tune, will there be no
> signal.

> -

>
> On 40 meters just about any wire more than 20 feet long outside should
> bring
> lots of signals. For receive only, you could just stick a 20 foot or
> longer
> wire in the antenna jack and hear something unless you are inside a
> building that has lots of material that radio waves will not penetrate.
>
> If you have an antenna up that is even within 50% of being intune it
> should
> receive lots of signals.

Thanks Ralph,

All I get is a click when I touch a 30ft wire. I've tried moving it
through the circuit and it goes from clicks to a mains hum about 1/2
way.

There is a filter circuit, after the aerial.

Cheers, Camerart.




--
Camerart

[vk3ye]

"Camerart" <Camerart...@radiobanter.com> wrote in message
news:Camerart...@radiobanter.com...

> All I get is a click when I touch a 30ft wire. I've tried moving it
> through the circuit and it goes from clicks to a mains hum about 1/2
> way.

30ft is near enough to a quarter wavelength on 7 MHz so that should be long
enough to pick up signals, especially if you've got an earth connection. An
end-fed half wave is a high impedance antenna and your transceiver is low
impedance. If you do use an end-fed half wave you need a L-match type
antenna coupler to ensure good power transfer.

I'm guessing the mains hum is heard when tapping at the input of the audio
amplifier. This proves that the audio chain is working at least.

If not there's a problem with the receiver's detector that in this design is
the final amplifier stage. Have you tried a locally generated signal to see
if that's heard? If it isn't I'd be checking to see if the xtal osc is
functioning.

It should work given the number built, but I haven't had great performance
from similar circuits; and the Foxx receiver is very much a compromise.
Something with a few more parts will deliver appreciably better performance.
Also stages that do only one thing are easier to optimise and troubleshoot
than those that try to do lots in a few stages.

I find it interesting that a design that uses 3 transistors for switching
and 1 transistor for sidetone can't afford to add 4 diodes and maybe an
audio preamp to form a decent receiver with a good balanced mixer. My own
bias would be to compromise on the switching but not on the receiver
performance. A good but still simple DC receiver is something like
http://www.phonestack.com/farhan/dc40.html My version is demonstrated at
http://www.youtube.com/watch?v=Tc2ofe7T7Rw

Still, the above is a bit of a rant and if lots of others have got it
working fine, yours should work too. When you do it pays to use a resonant
40 metre dipole rather than a random wire (better receivers are less
critical due to higher sensitivity & selectivity).

[Camerart]

vk3ye;798294 Wrote:
> "Camerart" Camerart...@radiobanter.com wrote in message
> news:Camerart...@radiobanter.com...

> -

> All I get is a click when I touch a 30ft wire. I've tried moving it
> through the circuit and it goes from clicks to a mains hum about 1/2

> way.-

Thanks vk3ye,

I've just joined a Ham culb and this is my first radio. I got my
licence in 1985, so I must have learned this all before, and forgotten
it?? There is also someone at this club who is making one. He will
help me as well. I asked this forum, as a way of getting a perhaps
different view, also as a crash course for me.

I'm puzzled about one transisor, at the point where I get a mains hum
between it and the earphone and I can check there is a connection from
the aerial conector and this transistor. I tried an oscilloscope on the
transistor, there is a crystal frequency at the Base, but not much on
the pin that goes on towards the earphone. I don't know what to expect.
but I feel suspicious.

Thanks, Camerart.




--
Camerart

[Camerart]

Camerart;798306 Wrote:
> Thanks vk3ye,
>
> I've just joined a Ham culb and this is my first radio. I got my
> licence in 1985, so I must have learned this all before, and forgotten
> it?? There is also someone at this club who is making one. He will
> help me as well. I asked this forum, as a way of getting a perhaps
> different view, also as a crash course for me.
>
> I'm puzzled about one transisor, at the point where I get a mains hum
> between it and the earphone and I can check there is a connection from

> the aerial connector and this transistor. I tried an oscilloscope on

> the transistor, there is a crystal frequency at the Base, but not much
> on the pin that goes on towards the earphone. I don't know what to
> expect. but I feel suspicious.
>
> Thanks, Camerart.

FOXX-3 update,

Last night, I remembered there is an offset side tone control, that I
hadn't touched yet. I tried turning it, and this seemed to start it up.
I could hear faint morse code. This morning I'm going to try to tune
the aerial, and see if I can get clearer signals.

Cheers, Camerart..




--
Camerart

[Camerart]

FOXX -3 further update.

Yesterday I changed the 10yrd wire to the recommended 20.1 MTR wire.
Before there was the faintest morse signal, now I'm back to nothing.

One question, I notice that aerials have insulators on them, I have
wrapped the other end o0f the aerial round a nail on my bottom fence, is
this ok.

Today I'm going to change the toroid windings, and experiment a bit.

Any tips welcome

Cheers, Camerart.