On 16 abr, 04:27, "Bob D." wrote:
I recently bought an Icom IC-R3 (hand held communications receiver) and a
Yaesu VX-7R handy-talky (can tune .5 to 1000 Mhz). Both of these devices
can't pick up a single shortwave signal. And this is on a long wire antenna,
not the rubber duckies. (They both receive great on VHF/UHF. The IC-R3 even
manages to pick up fringe TV channels.) The same antenna connected to my old
Kenwood 599 receiver brings in plenty of HF signals, both shortwave
broadcast and amateur.

How can these two new receivers be soooo bad????? I live within a mile of an
AM broadcast station, could that be the problem? (It doesn't bother my old
Kenwood though!) Is anyone successfully listening to shortwave stations with
either of these radios?

I'm was going to buy a new HF amateur rig, but now I'm scared that it might
have poor reception at my location also.

--
Bob D. ND9B
Hello Bob,

This is a common problem with hand held wide band receivers. These
receivers cannot handle large signals and picking out the small signal
you want to hear. It is not Kenwood R5000, Drake or JRC.

I have the same problem with an AOR8200 MKII. There are several
solutions.

When the interference comes from a single nearby transmitter, you may
build a "notch filter" for that single frequency. Such a filter may
consist of a series resonant circuit parallel to the antenna input.

It is very likely that the overload is caused by many stations
together. In that case you may build a tunable preselector (some
inductors with an [old] plate variable capacitor). I have that in
combination with my AOR8200. The result can be amazing (from hearing
a station not all to clear reception after insertion of the
preselector).

The disadvantage is that you have to tune the preselector each time
you change your frequency with more then some percent.

For the time being, you may use the smallest possible antenna that
still gives reasonable reception and you may use the attenuator
function (if present).

If you are not in electronics, try to get some help from a radio
amateur.

I use this type of preselector, the zig zag lines are non-coupled
inductors with a tap on it, C = the tunable capacitor. View with fixed
sized font setting (for example Courier).

----------------------
/ | \
\ | /
/ | \
\ --- c /
/ --- \
\ | /
inp----- | --------output
/ | \
\ | /
gnd----------------------------------- gnd

Best Regards

Wim
PA3DJS