[IRCA] accurian receiver review - part 3 of 4

["Bob Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

Review of Radio Shack Accurian 12-1686 HD receiver
by Bob Foxworth    - in 4 parts

begin part 3 of 4

AM HD. In Tampa there are two AM HD signals, on 820
and on 970. These are high power (daytime) signals
located just a few miles distant from me. Both of
these signals will decode to HD, at this close range.
The big question of course is what is the limit of
coverage at which the HD decode fails when analog is
still usable.

I am able to force a temporary un-lock of HD on these
two AMs by just rotating the loop. There are two
critical angles in which HD is marginal (even at
this range) due to loop nulling. A nontechnical user
who uses "set and forget" for his/her loop placement
in the house runs a small chance of never hearing
a desired HD AM, and may not understand the need
for better loop placement, as the "collective
experience" of outside antennas is now a lost art.

When any non-HD frequency is tuned in, the display
will say (for example) "860 AM". When tuning in,
say 970, the display will pick up and show the call
letter ID in a second, or even less than a second.
It then takes 7 or 8 seconds for the audible decode
to change to HD sound. When this happens,a HD
logo becomes visible on the display, and a 6 line
bar graph showing signal strength becomes visible.
The bar graph is not rapidly responsive to input
level changes (loop rotation, etc) and it is unclear
what exactly drives it, as FM signals show most
or all bars while AM show just some, and of course
only on my 2 local HD signals.

The main effect of HD is to brighten the high end
audio response and to create a sensation of stereo
separation. This effect is noticed best when the
user is directly in front of the set (or using a
headset) and is somewhat less pronounced when
listening from a distance. The effect on WMGG (a
Spanish music format) is quite a lot more noticeable
than it is on WFLA (talk) where it is (to me) only
somewhat apparent.

The display latches the call letters which continue
to show, even if the HD unlocks. WMGG has a scrolling
line of text with their "megaclasica.com" web
address. WFLA has no such data stream and the display
just shows "artist:  title:" in the area where the
date and time, or scroll, otherwise appear.

It's interesting to tune the set to 960 where the hiss
is present on a dx398 etc, in this case a grinding
bubbling type noise is heard, not too different than
the analog case. (I'm sure someone is wondering
about that). Incidentally WFLA hiss is somewhat
louder on 960 than on 980 on an analog set.

One of my plans is to determine the rough edges
of the AM HD coverage. I would do this by taking
the set in my truck, powering it from an AC inverter
and setting up at various locations. I soon found
that the inverter I have plays very badly with
this (and probably other) sets, on AM, and this
option is completely unworkable for me. I need to
come up with a 5 VDC 5 A clean source. In the
meantime I do have some results to offer.

I set up the set at an indoor location in southern
Pasco county, close to the intersection of SR41
and SR-54. Neither HD signal was even decently
copiable in analog, let alone getting any HD. I
need to go back and see if this is environmental.

On the other hand I set up the receiver indoors at
the K of C meeting hall on Fruitville Road in
Sarasota, where WFLA gave just fragmentary bursts
of HD. However I was surprised to see that WMGG
gave a solid decode there. This is about 50
miles south of Tampa.

FM usage is somewhat more satisfying. What is
interesting to me is that the blend from FM analog
to FM HD is hardly noticeable. It is more of a
perception of a subtle difference, than the striking
change I hear on 820 AM. The sound section of this
radio, to me, is innately good enough that it renders
analog FM quite nicely, and the program feed the
FM folks use is not that much enhanced with HD.

I had issues with decoding HD on a number of the
FM offerings depending on how I placed the antenna,
which one I used, and where I was in the house.
The dipole needed to sometimes be fully extended
and positioned, with placement issues somewhat
like those for the AM loop. I am not a FM DXer and
may not go a lot farther with this issue.

Some FM customers will want the secondary programming
which is available on FM. I won't do an exhaustive
rundown of what's on the dial here as it won't help
many in other markets. Non-comm WUSF is frequently
but not always running separate programming on their
secondary, which IDs as "WUSF eighty-nine seven two."
They show as "89.7-1" or "89.7-2" when tuned in and
the "new" station appears as if "dropped in"
between the existing ones. When they both carry NPR
news, the -2 is 7 seconds behind the -1. Some
stations like WSJT 94.1 have the same programming
on the -1 and the -2, with 7 seconds separation.
WUSF has the analog fallback timing solved while
the fallback on WSJT is a bit over a second out.

end part 3 of 4





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