New to AM Communications/Solid State AM Hints

New to AM Communications/Solid State AM Hints

Post by Douglas Gontz -- n3j » Thu, 03 Nov 1994 00:43:19


        I just recently got an antenna that alows me to use 160m and 75m
bands.  I've heard some people using AM and have been able to talk with
folks with little trouble.  The problem is I'm not sure if I have the
rig set correctly.

        The rig is an ICOM 735.  I adjusted the carrier insertion to the
recommended 40 watts.  I've found by way of talking with friends that I
get the best reports by running the speech compress and keeping the Mic
gain relatively low.  However, I've noticed that no matter what I do the
radio seems to drop power as I modulate.

        Does anyone else have any experience with using ICOM 735's on Am
and, possibly, any suggestions on better ways to set the rig up.  Also,
I'd like to hear from anyone that knows of any solid state rigs that run
AM okay.  I'm thinking about upgrading the rig and I want to make sure
the new station will work well on AM.  I'd like to stay with ICOM but I
could be persuaded to change brands if there are better rigs on the
market.

        Thanks in advance for any and all help.  I really appreciate.

73 --- Douglas, n3jxb

 
 
 

New to AM Communications/Solid State AM Hints

Post by Jim Garv » Sun, 06 Nov 1994 07:56:17




Quote:>    I just recently got an antenna that alows me to use 160m and 75m
>bands.  I've heard some people using AM and have been able to talk with
>folks with little trouble.  The problem is I'm not sure if I have the
>rig set correctly.

>    The rig is an ICOM 735....

Adjust the rig until it weighs over 50 lbs. smells musty and glows in the
dark.  AM operation with solid state is sometimes considered a radio 'sin'
but maybe AM'ers are more tolerant than other species.
If you insist on continuing this sacriledge, then I suggest you get a
good oscilloscope with 50 Mhz or more bandwidth and monitor your RF output.
Do not connect the probe directly but stick it into the PA box or othewise
loosely couple to the RF output.
Watch out for peak clipping (flat tops) and straight lines at the minimums.
These are no-no's.
Without the scope, you may have to depend on comments from the receiving
stations.  These may or may not be accurate and also depends on what band
you are on.  For instance on 11 meters you can usually get it right if you
interpret the opposite of whatever they tell you.
For some solid state rigs, leave the mike gain where it is normally used
for SSB.  Start out with the carrier insertion at minimum and very gradually
increase it until the receiving station tells you you are starting to sound
fuzzy or distorted.  Then reduce the carrier until that goes away.  Never,
under any circumstances, use compression on AM.  This is a cardinal sin.

--

I speak only for myself.            How will you spend it?" - Barnaby Jones

 
 
 

New to AM Communications/Solid State AM Hints

Post by Anthony R. Gol » Mon, 07 Nov 1994 18:26:22



Quote:

>         The rig is an ICOM 735.  I adjusted the carrier insertion to the
> recommended 40 watts.  I've found by way of talking with friends that I
> get the best reports by running the speech compress and keeping the Mic
> gain relatively low.  However, I've noticed that no matter what I do the
> radio seems to drop power as I modulate.

The downward power indication is just showing you that you are running
way above linear power. The upward mod is being clipped and flattened
and the downward mod is okay, so the average is dropping.

Reduce the power until the average is flat. If you have a scope you
will find it easier.

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