[Premium-Rx] RA 6790/GM(R-2174B) LSB mistuning

[Karl-Arne Markström]

It seems likely that a cause for this problem may be a mix-up of
symmetrical and sideband offset filters in the FL1 position of the RA6790.

At initialization, the BITE routine checks the filter complement of the
receiver and creates a filter table. If the FL1 position should contain 
anything else than an LSB or symmetrical filter, there will be problems.

This is elaborated in section 5.7.6 of the T.O. 31R2-2URR-251 manual.

73/

Karl-Arne
SM0AOM

----- Original Message ----- 
From: "Ahmet Gundes" <ahmet-m at usa.com>
To: "Choe" <hankukp at kg21.net>; <premium-rx at ml.skirrow.org>
Sent: Thursday, May 26, 2005 12:04 AM
Subject: Re: [Premium-Rx] RA 6790/GM(R-2174B) LSB mistuning


Hello,


I am not familiar with RA6790, however i have a similar situation with a WJ8888 where the actual tuned

frequency is 10 KHz off of what display shows. It is my guess that the Second LO circuitry needs to be 

checked. Prescalers, PLLs... etc.  In AM mode you would probably also off tune the receiver to get the correct

frequency.   You may want to check the Second LO. Again, I do not own an RA6790. There are many RA6790 experts 

on the PremRX who would definitely give you an expert diagnosis.

 

Good luck.

Ahmet

....
 

Hi all members !

 

My receiver RA 6790/GM(R2174B) mistune  by -6.7KHz.

For instance, I tune to 1,000 KHz in AM mode and I press USB button then it it tunes exactly same frequency

and I can hear am signal in USB mode but  if I press LSB  Button I shuld detune -6.7KHz, it means I should tune to

993.3 KHz. Is there any body experience with similar problem or any theoretically suspected fault point ?

I can calculate 6.7=10-(1.65+1.65)KHz.

 

Best regards,

Choe 


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