Next time you hear it, check your loudest local AM stations ... maybe overload
from your superduper antenna.

jw
wb9uai

On 23 Sep 2003 04:12:51 GMT, (J999w) wrote:

Next time you hear it, check your loudest local AM stations ... maybe overload
from your superduper antenna.

jw
wb9uai

he,he
Yes, I think the antenna has something to do with it. It was WWCR on
3210 causing a harmonic (?) on my sony. Thats nearly 1khz off. This
happened several times tonight with those domestic based powerhouses.

Never happened before. Guess thats what the antenuator is for.

mike

A passive preselector between your antenna and radio would be better, that way
you're not throwing away 20db for hearing the good stuff.

Now 0645z and 4845.0 MAURITANIA is peaking S9+40 db !! WOW !

jw
wb9uai
milwaukee

On 23 Sep 2003 06:58:16 GMT, (J999w) wrote:

A passive preselector between your antenna and radio would be better, that way
you're not throwing away 20db for hearing the good stuff.

Now 0645z and 4845.0 MAURITANIA is peaking S9+40 db !! WOW !

jw
wb9uai
milwaukee



Cool, that beats my picking up 50 kw Radio Orbita 3 from Russia or the
African channels (Botswana and Nigeria) booming last night.

Not bad for a sony 7600GR portable eh?

I figured out the image problem. I think it's the voltage limiting
diodes I place yesterday across my antenna input to ground.

mike

Cool, that beats my picking up 50 kw Radio Orbita 3 from Russia or the
African channels (Botswana and Nigeria) booming last night.

Not bad for a sony 7600GR portable eh?

I figured out the image problem. I think it's the voltage limiting
diodes I place yesterday across my antenna input to ground.

mike

That is exactly what it is assuming yor RX uses a 455 kHz IF.
3210 -(2X IF)=2300.
Diodes across an antenna are always a bad idea.

Dale W4OP

Dale Parfitt schrieb:

Cool, that beats my picking up 50 kw Radio Orbita 3 from Russia or the
African channels (Botswana and Nigeria) booming last night.

Not bad for a sony 7600GR portable eh?

I figured out the image problem. I think it's the voltage limiting
diodes I place yesterday across my antenna input to ground.

That is exactly what it is assuming yor RX uses a 455 kHz IF.

Which, btw, it does. And it doesn't have too great an image rejection
either (~40 dB). When using a big antenna with a 7600G(R), I'd advise a
passive preselector / antenna tuner, not only for better image rejection
but also against IM products (here in Central Europe signals are strong
enough to produce IM products on the whip alone). It's a lot of receiver
for the money, but in no way an AR7030+... (Except for AM demodulation,
that is - this sounds rather crappy and distorted on the AOR, but that's
what the excellent synch is for.)

Stephan
--
Home: http://stephan.win31.de/ | Webm.: http://www.i24.com/
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Reply to newsgroup only. | See home page for working e-mail address.

On Wed, 24 Sep 2003 15:47:10 +0200, Stephan Grossklass
wrote:

Dale Parfitt schrieb:

Cool, that beats my picking up 50 kw Radio Orbita 3 from Russia or the
African channels (Botswana and Nigeria) booming last night.

Not bad for a sony 7600GR portable eh?

I figured out the image problem. I think it's the voltage limiting
diodes I place yesterday across my antenna input to ground.

That is exactly what it is assuming yor RX uses a 455 kHz IF.

Which, btw, it does. And it doesn't have too great an image rejection
either (~40 dB). When using a big antenna with a 7600G(R), I'd advise a
passive preselector / antenna tuner, not only for better image rejection
but also against IM products (here in Central Europe signals are strong
enough to produce IM products on the whip alone). It's a lot of receiver
for the money, but in no way an AR7030+... (Except for AM demodulation,
that is - this sounds rather crappy and distorted on the AOR, but that's
what the excellent synch is for.)

Stephan


Hmmm...guess the diodes are not such a hot idea after all.
Easy enough to desolder and remove them. That would leave my 2.2k ohm
resistor as a bleed off inside my antenna tuner. I will order a gas
arc breakdown tube for major voltage impulses and be done with it.
Or alternately, should I run into a pile of cash sometime soon, buy an
ICE model 197 RF limiter/arrester.

mike

Mike,

Having some form of Antenna Input Protection is a Good Idea.
- - - Instead of a Single Diode: *--|--@
* = Ground -and- @ = Antenna


# 1. Good - Try a two sets of Double Diodes.
*--|--|--@
*--|--|--@


# 2. Better - Use a Gas Discharge Tube (GDT) for EMF shunting and a
10K Ohm Resister for Static Electricity Bleed-Off to Prevent Static
Electricity Build-Up and Discharge.

*----(o----@
*--\/\/\/--@

# 3. "Best" is an Improvement to #2 would be to replace the 10K Ohm
Resister with a with a 10K Audio Taper Potentiometer.
+ One Leg/End goes to the Antenna.
+ The 'other' Leg/End goes to Ground.
+ Then the Center of the POT goes to the Radio.
+ The Radio's Ground is also connected to the common Ground.
NOTE: The 10K POT now acts as a Bleed Resister and also an External
RF signal Attenuator.

*----(o----@
*--\/\/\/--@
*====^=====@
*====|
*====R

R = Radio

iane ~ RHF
..
..
= = = mike
= = = wrote in message . ..

Sony 7600GR portable

I figured out the image problem. I think it's the voltage limiting
diodes I place yesterday across my antenna input to ground.

mike

*cough* NE-2 bulb *cough*

;-)

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

"mike" wrote in message
...

he,he
Yes, I think the antenna has something to do with it. It was WWCR on
3210 causing a harmonic (?) on my sony. Thats nearly 1khz off. This
happened several times tonight with those domestic based powerhouses.


It could be mixing with a local AM station. 3210 - 2300 = 910 khz. Of
course if that's the case you should probably be able to hear the
programming from both stations at the same time, as I have with local AM
stations.

--
Tom Sevart N2UHC
Frontenac, KS

http://www.geocities.com/n2uhc