[ICOM] 756Pro Alinement

[Ken]

Thanks Larry, this sounds like something I can do.  I have digipan (I think
v1.7) on the computer with an interface I use for PSK.

I will be checking this version.  My hearing isn't as good as it should be
and I was concerned about being able to tell with the tones with the
alignment procedure were correct.  With the program I can "see" the correct
tone setting.

Yes, I'm sure it's only the R32 for fine adjustment required.

Thanks again,

Ken H>


----- Original Message ----- 
From: "Larry Benko" <w0qe at bnk.com>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Tuesday, May 25, 2004 10:45 AM
Subject: Re: [ICOM] 756Pro Alinement


> The 756Prro alignment is actually very easy to do.  The service manual
> explains it all but basically the entire frequency chain is controlled
> by the 64.000MHz oscillator (X52, CR-338).  Coarse adjustment is done by
> adjusting L52 (must open radio up) and the fine adjustment is done by
> R32 (accessable via the right side of the radio).  The DSP controls the
> USB/LSB offsets etc. and once the master oscillator is set there is
> nothing more to do.  I am assuming you only need to do a fine adjustment
> (R32).
>
> Before doing any adjustment make sure the RIT is OFF and the PBT is set
> to default.  In my opinion the easiest and possibly the best way to do
> the alignment is to tune the radio to the highest WWV frequency
> broadcast you can hear well (5, 10, 15,20,25MHz).  Now download Digipan
> ver 1.7 (I think that is current) and load it on you PC. Make sure the
> option to show frequencies is on.  Take the audio output of the radio
> and put it into your soundcard.  Adjust the volumes so the Digipan
> "waterfall" display is not too dark and not washed out.  Set the 756Pro
> to exactly the frequency you are expecting WWv to be even if  1KHz
> higher sounds bettter.  Now switch the 756Pro back and forth from USB to
> LSB.  WWV transmits a 500 Hz tone or 600 Hz tone during most of the
> time.  These tones appear as continuous lines in the Digipan display.
> Click you mouse on the line and Digipan measures the frequency to
> 0.1Hz.  What you are trying to do is to get the tones to be exactly the
> same frequency for both USB and LSB reception.
>
> While this may sound hard, if you do any PSK31 operation it is only a
> few minute test.  I have been able to set my 756PRO and 746PRO (with the
> CR-338 osc.) to within 1Hz of perfect easily.  By the way make sure the
> rig has been on for a while before tweaking R32.
>
> 73,
> Larry, W0QE
>
>
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
>