Re: [IRCA] SRF-59 Alignment Procedure

[Deane McIntyre <dmcintyr@xxxxxxxxxxx>]

On 23-Dec-07, at 1:57 AM, D1028Gary@xxxxxxx wrote:

> Hello Bill,
>
>      The IF of this SRF-59 is a mystery.  There is  only one  
> adjustable AM IF
> transformer on the radio's circuit board, and this is  the only  
> adjustable AM
> component in the radio (the coils on the loopstick are  not  
> adjustable by
> sliding, and there are no trimming capacitors on the  tuner).  Most
> single-conversion radios give a hint of the IF by at  least weak  
> image reception twice the
> IF lower than strong locals at the top of  the dial, but this radio  
> has no
> image reception whatsoever.  The secrets  are apparently contained  
> within Sony's
> proprietary 30-pin IC chip hidden  underneath the main circuit board,
> resulting in performance far exceeding what  technicians of the  
> 70's and 80's (like
> myself) are accustomed to.
>

Count me in as one of the SRF-59 fans - brought one a couple of weeks
ago and it fully lives up to its reputation. Furthest DX to data from  
Calgary
AB is Cuba on 530 which I have logged several nights. WOAI-1200 is  
heard most
nights in the null of the Vancouver station. Am thinking of starting  
a new log
of stations logged with this little wonder which is a real winner and  
much more
portable that my GE Superadios and Radio Shack TRF's.

With regard to its IF frequency - my usual procedure to check this is to
use by DX-440 to measure the oscillator frequency. I turn the BFO of  
the DX-440
on and with WWV tuned in use the BFO pitch control to zero beat WWV.  
Then I
tune the radio under test to a weak station and determine the  
oscillator frequency
with the DX-440. The IF is of course the difference between the  
frequency
the radio under test is tuned to and the oscillator frequency.

I did this this morning with the SRF-59 and I and perplexed. With  
weak CFCW-790
tuned in on the SRF-59 as accurately as I can by ear, I measure the  
oscillator
frequency to be 1696 KHz, which would indicate a 906 kHz IF  
frequency. I checked
at a few other places in the band and the difference was always 906  
kHz. What
gives - I radio is not supposed to have an IF frequency in its tuning  
range. I
do hear a weak birdie on local CKDQ-910 which is normal for a radio  
with a 455 kHz
IF bur would also be expected for a radio with an IF near 810. Double  
checked to
see if there was any trace of an oscillator signal from the SFR-59  
400 - 500 kHz
above the tuned frequency, nothing at all heard.

Only radio I know of that has an IF frequency abound 900 kHz is the  
WW II era
BC-348 aircraft receiver, where the IF is 816 kHz. But they did not  
cover
the standard AM radio band.

The mystery of the SRF-59 deepens.

73,

Deane McIntyre VE6BPO


_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/irca

Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx