modify an AM tuner to go on 4mhz!!!
 

In you opinion, can I push my AM tuner from its 500-1600 khz to 4000khz
using some of the various mods presented in the previous post?
Or it's really too much?
--

In you opinion, can I push my AM tuner from its 500-1600 khz to 4000khz
using some of the various mods presented in the previous post?
Or it's really too much?

Tony-

I didn't see your previous posts. Yes, you should be able to modify the tuner,
but it means replacing the front-end tuned circuit as well as the local
oscillator's tuned circuits.

Another approach is to add a converter stage between the 4000khz antenna and
the antenna input connector of the tuner. Such a converter might have a
4000khz preamplifier stage, a converter stage and a local oscillator stage. If
the local oscillator were crystal controlled, you might be able to tune the
frequency on the AM dial, with frequency determined by adding a constant.

73, Fred, K4DII

"Fred McKenzie" wrote in message
...

Another approach is to add a converter stage between the 4000khz antenna
and
the antenna input connector of the tuner. Such a converter might have a
4000khz preamplifier stage, a converter stage and a local oscillator
stage. If
the local oscillator were crystal controlled, you might be able to tune
the
frequency on the AM dial, with frequency determined by adding a constant.

This is the best approach. It's best to use an AM car radio that has
analogue tuning for this sort of thing. A crystal for 5 MHz would be OK - 4
MHz would come up at 1000 kHz on the dial.

An excellent project is a converter using 4 & 5 MHz crystals and a tunable
front end. This will give you a receiver that tunes continuously between 3.5
and 7.5 MHz in 4 bands. You will need a double tuned circuit at the front
end to resonate over this range. Add a 455 kHz BFO for SSB.


73, Peter

On Wed, 8 Sep 2004 00:36:01 +0200, "Tony"
wrote:

In you opinion, can I push my AM tuner from its 500-1600 khz to 4000khz
using some of the various mods presented in the previous post?
Or it's really too much?

What do you expect to hear with an AM tuner in say 3000-4000 kHz
range? There is very few AM transmissions.

In addition you would need a beat frequency oscillator, to make sense
of at least some of the transmissions.

Paul

"Paul Keinanen" wrote in message
...
On Wed, 8 Sep 2004 00:36:01 +0200, "Tony"
wrote:

In you opinion, can I push my AM tuner from its 500-1600 khz to 4000khz
using some of the various mods presented in the previous post?
Or it's really too much?

What do you expect to hear with an AM tuner in say 3000-4000 kHz
range? There is very few AM transmissions.

In addition you would need a beat frequency oscillator, to make sense
of at least some of the transmissions.

Paul

I too would encourage the converter approach.
As to what there is to hear- this is the tropical AM broadcast band and some
of the rarest catches are located here, although I think I would prefer a
radio with a bit more sophistication.

Dale W4OP

A crystal for 5 MHz would be OK - 4
MHz would come up at 1000 kHz on the dial.

Peter-

With high-side injection wouldn't the dial tune backwards? 4000khz would
appear at 1000khz, but 4500kHz would appear at 500khz on the dial.

If Tony can adjust to the backwards dial, I agree that a 5000khz converter
crystal would be the better choice, since it might be easier to filter out
images at 6000khz than images at 2000khz when using a 3000khz crystal.

73, Fred, K4DII

Now we must find a scheme for this...

--
--
I use PGP. Ask for my key if interested.
-

"Fred McKenzie" ha scritto nel messaggio
...
A crystal for 5 MHz would be OK - 4
MHz would come up at 1000 kHz on the dial.

Peter-

With high-side injection wouldn't the dial tune backwards? 4000khz would
appear at 1000khz, but 4500kHz would appear at 500khz on the dial.

If Tony can adjust to the backwards dial, I agree that a 5000khz converter
crystal would be the better choice, since it might be easier to filter out
images at 6000khz than images at 2000khz when using a 3000khz crystal.

73, Fred, K4DII

"Fred McKenzie" wrote in message
...
A crystal for 5 MHz would be OK - 4
MHz would come up at 1000 kHz on the dial.

Peter-

With high-side injection wouldn't the dial tune backwards? 4000khz would
appear at 1000khz, but 4500kHz would appear at 500khz on the dial.

Yes it would. But it's no great hardship and improves one's mental maths!

If Tony can adjust to the backwards dial, I agree that a 5000khz converter
crystal would be the better choice, since it might be easier to filter out
images at 6000khz than images at 2000khz when using a 3000khz crystal.

Agreed. I have a h/b receiever that tunes 1.6 to 4.0 MHz as a tunable IF.
There are xtals every 2 MHz in its front end converter. Using a 2 MHz xtal
for the 4-6 MHz range hardly worked at all, and it was better to switch in
the 6 MHz xtal and accept backward tuning.

Another benefit is that 5 MHz xtals seem to be more obtainable than 3 MHz
xtals.

73, Peter VK3YE


73, Fred, K4DII

see http://www.dxing.com/tuning.htm for what is on various SWL freq.
segments and bands, including the 3-4 Mhz segment...

I just gave a talk on SWLing as an entry to amateur radio for our club:
see http://people.smu.edu/arc/swlfun.doc for handout
see http://people.smu.edu/arc/swlfun.ppt for talk powerpoint slides
*see http://people.smu.edu/arc/shortwave.html SWL radios for future hams

depending on your goals, you may find the comparison(*) of $50 spent on a
kit shortwave radio (ramsey SR-1 2 Mhz AM only kit) vs. degen 1103 digital
dial 0.1-30Mhz AM/SSB/CW radio interesting, esp. if $$ and performance are
important, and your major interest is not homebrewing but SWL listening?

That said, the first thing I ordered after getting the above radio was the
$10 converter kit from Jackson Harbor Press kits for an ELF/VLF (10-300
Khz) including 10 Mhz crystal (For marker, timebase..) to compliment a
VLF beacon transmitter we are designing and building ;-)

hth bobm
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