[IRCA] More on the SRF-59

["Rene Tetro" <rene@xxxxxxxx>]

After all of the discussion and generally positive comments on the various
DX groups about the SRF-59, I ordered one.  I figured for about $16 from
Amazon you can't go wrong.  Well, I got mine yesterday, and last night put
it through some "unscientific" listening tests.  Like many of you, I have to
say that I am very impressed at what the AM section of this little radio can
do for its size and cost.  A lot of its positives have already been
mentioned, so I'll confine my comments to one specific striking aspect of
the radio.

The selectivity and signal nulling capability is way beyond anything I've
seen in a radio this inexpensive and small.  First let me discuss the
antenna nulling.  Whether or not this is by design, when the radio is
rotated while listening to a very strong station, the radio's AM internal
antenna is capable of quite deep nulling of the station's signal.  For
example, I live about eight miles from KYW's 50kw IBOC-ridden transmitter.
I have measured their signal at about 95 mV/m at my house -- a mighty strong
signal, indeed. While tuning to 1060 and rotating the radio, the antenna
quite easily nulled KYW until the signal was almost unlistenable.  This is a
pretty remarkable feat given the station's signal strength at my location.  

I then tuned down 10khz to 1050 to see what would happen with KYW's IBOC
hash.  Again, because of the nulling capability, combined with the SRF-59's
decent selectivity, I was able to FULLY null the IBOC hash and listen to an
unid'ed Spanish station on 1050.  The Spanish station's signal was fully
listenable with no sign of KYW's IBOC.  A similar test was conducted at
1070.  Although no station was clearly discernable on 1070, as with 1050
there was no evidence of KYW's IBOC hash -- just normal weak background
nighttime carriers.  I tried the same test against WPEN's 950 nighttime IBOC
transmitter, which is also quite strong at my location (somewhere in the
order 25 mV/m).  The results were the same on both the main channel and
adjacent channels.  

This morning I conducted the nulling test on other strong stations (none of
whom have IBOC):  WFIL 560, WNTP 990, and WNPV 1440.  I wanted to see if I
got similar nulling capabilities across the band.  In each case I was able
to null the station's carrier to pretty much nothing.  As far as the
adjacents are concerned, I got the following results.  With WFIL nulled, I
was ale to listen to WMCA on 570.  With WNTP nulled I was able to listen to
WILK on 980. And with WNPV nulled I was able to pick out WILM on 1450 and
WNSW on 1430 (albeit both were very faint).

Overall, it's a pretty incredible little AM radio.  

My only complaint about the AM operation, as some others have expressed, is
the analog tuning.  It's been a long time since I had to mentally count
channels and listen for the channel changes as I tuned up and down the dial.
It did bring back memories, though, of lying in bed at night as a teenager
in the 60's and searching for a station by counting channels from a known
dial position.  "OK...that's WOWO on 1190, WOAI on 1200, WCAU on 1210, WGAR
on 1220.  Here's 1230!  Let's see what I can get on the graveyard."  

I also found that the FM is not all that sensitive.  Listening to some
locals with weaker signals at my location (like WXPN, WRTI, WBMR, and WPPZ
was difficult, if not impossible.  All the local full class B FM's, however,
were clear with full quieting.  But, since I did not buy the radio for it's
FM, this is not an issue for me.

Bottom line:  it's probably about the best $16 I've ever spent on a radio. 

73,
Rene'

Rene F. Tetro
Chief Engineer
Salem Communications - Philadelphia
WFIL-AM / WNTP-FM
117 Ridge Pike
Lafayette Hill, PA  19444
Voice:  610-828-6965  Ext. 41
Fax:  610-828-6725
Email:  rtetro@xxxxxxxxx



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