Additional IBOC Hash Experienced

Thu May 10 00:28:09 EDT 2007

At my QTH, WRKO has a killer signal--more than 200 mV/m according to
V-Soft. On my car radio, and ONLY on my car radio, WRKO's second
harmonic wipes out WLYN (but not WFEA). The fact that the phenomenon
occurs only on one radio and a radio with a front-end tuned-RF
stage--but not on at least one other radio with such a front-end stage
(GE Super Radio III), demonstrates convincingly that the problem is in
my car radio and not at WRKO. There is sufficient nonlinearity in the
car radio's front end to generate a bit of second harmonic from WRKO's
strong signal. If the car radio tuned up in the ham bands, I doubtless
would have the problem at 2300 (WTTT), 2940 (WAZN) and 3020 (WWZN).
Although a problem at WNNW may exist, it is more likely that, umm, the
problem is in your set.

Dan Strassberg (
eFax 1-707-215-6367

----- Original Message ----- 
From: "Laurence Glavin" <>
To: <>
Sent: Wednesday, May 09, 2007 4:27 PM
Subject: Additional IBOC Hash Experienced

>A few days ago, it crossed my mind the check on WSMN-AM 1590 in
> Nashua, NH.  I was on route 93 at the time, and instead of audio
> from that station, I received the kind of 'hash' one experiences
> when tuning to a frequency adjacent to an AM station broadcasting
> in HD.  But WUNR-AM 1600 doesn't do that (yet)...then it occurred to
> me that I wasn't far from the WNNW-AM 800 tower, and WNNW does
> broadcast in HD days.  That means I was probably getting the 'hash'
> from double WNNW's frequency, 1600.  So in the future, if more and
> more AM stations between 540 and 800 go IBOC, stations near double
> their frequencies will get the kind of interference now noted only
> among outlets near HD broadcasters.  Thus, if WEZE-AM 590 were to
> install HD, listeners not far way from Medford could be deprived of
> WDIS-AM 1170 (a great loss).  Or if WRKO-AM 680 whent HD, there
> goes reception of WFEA-AM 1370 (WLYN-AM 1360 is already a casualty)
> for some people.
> =
> Municipal Bond Specialists:
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