Two Older Sony Receivers:
ICF-7601 and ICF-SW7600
Sony 7600 Series
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Today we will be looking at two older Sony portables coming in the handy
pocketbook-sized format that has proven to be a good compromise over
The ICF-7601 measures 192.5 × 122 × 35 mm³ (or 7-37/64
× 4-51/64 × 1-3/8 inches), the ICF-SW7600 is slightly
smaller at 191.2 × 118 × 32.3 mm³ (or 7-33/64 ×
4-41/64 × 1-9/32 inches). Both use a rather powerful speaker
that is 7.7 cm or approx. 3 inches in diameter, both are dual conversion
designs, and both have been out of production for a good 10 years
- but that's where the similarities end.
of them will be compared to my faithful old ICF-SW7600G, a well-established
model in this class and my first serious shortwave rig. So, what can
you expect when buying one of these on the used market?
on One Nightstand - from the front, first our two contestants, then
the ICF-SW7600G, and finally (more for fun) the old Philips D1835
from the mid '80s. The alarm clock will not be dealt with in this
review, but it be mentioned that it's radio controlled - wouldn't
you also be with so many radios around?
A look at the ICF-7601
History and Concept
is the older of the two, having been made from about 1988 to 1993.
Its sales price was some US-$ 129 or so. Apart from the small microprocessor
controlling the switch functions, it's 100% analog. It covers mediumwave,
the three lowest shortwave bands from 120m to 75m (or longwave, on
the ICF-7601L) and FM as a single conversion unit (with an IF of 455
kHz for AM and 10.7 MHz for FM, respectively), the shortwave bands
from 60m through 13 m, including 22m (except for the band segment
around 19 MHz), are covered with a dual conversion design with a 1st
IF of 10.7 MHz +/- 350 kHz and again a 2nd IF of 455 kHz. This dual
conversion design is quite interesting, since it uses a fixed (crystal
controlled) 1st mixing frequency for each band, so what's varied with
the main tuning knob is the mixing frequency for the second mixer.
Since this is lower than the 1st mixing frequency (up to a factor
of 3 for 13m), better frequency stability can be obtained this way,
which is always critical for analogs with their notoriously drifty
LC controlled oscillators. On the 1st IF, inexpensive ceramic filters
similar to those used in FM IF chains are used to keep frequency ranges
outside the currently selected band away from the 2nd mixer; life
of the 1st mixer is made easier by antenna tuning circuits switched
together with the cystal oscillators. The telescopic whip antenna
(about 69 cm in length and with a provision for attaching an inductive
antenna coupler) is used for the dual conversion shortwave bands and
FM, the other ranges have to make do with the built-in ferrite rod.
front of the ICF-7601 is unlikely to overwhelm anyone with its complexity:
Speaker grille on the left, scales on the right with some sliders
and buttons underneath and a small tuning LED in the upper right.
Four of the buttons are used for selecting the SW1 (or LW), SW2-10
(dual conversion), MW and FM bands, another turns the radio off, there's
a "hold" slider to disable button operation and last but
not least the shortwave (2-10) band selection slider (which looks
like it was taken over from an ICF-4900 or somesuch because it's rather
small - parts recycling?). On the left side of the case you can find
a DC in socket, a mono headphone socket (which is rather stereo friendly)
and the usual useless carrying pouch, on the right there's the volume
slider (which could be a bit easier to move), the tone switch and
the main tuning knob. Ah yes, there's a small stand on the back (a
bit flimsy for my taste), right next to a small world time zone map,
along with a battery compartment for 4 AA (R6) cells; finally there's
a telescopic antenna on top. That's all.
to me that back then the ICF-7601 was Sony's entry-level shortwave
rig, similar to the ICF-SW35 today. Indeed, the case construction
is not quite as stable as I'm used to from other "7600"
receivers, and the receiver concept looks a bit like an ICF-4900 with
more bands and features added in a larger case with a larger speaker.
Still, analogs with this kind of performance and quality are no longer
being made today.
That's what you've all been waiting for, right?
sensitivity seems to be good even with no preamp FET used, but selectivity
is W-I-D-E. That's not overly amazing with just a single FM IF filter.
One should try replacing it with one of Murata's SFT10.7 series filters
(these are the equivalent of two conventional SFE10.7 filters at comparable
insertion loss), maybe the 180 or 230 kHz variants. Scale accuracy
isn't outstanding on my sample.
the effective sensitivity of the ICF-7601 is so close to that of the
ICF-SW7600G that even now I can't decide which one is better in this
regard! (One problem is the very different frequency response of both
rigs, which makes comparisons a bit difficult.) In terms of selectivity,
the 7600G is ahead, but apparently mostly due to its aggressive audio
lowpass filtering. Scale accuracy is quite OK.
SW1 range, I noticed good sensitivity, though image rejection isn't
particularly exciting and I did see some mixing products from higher
bands in the 2...3 MHz range. Due to the large range covered, the
scale is rather coarse and not a big help on 75m.
SW2-10 bands which are spread over approx. 650 kHz each, the scales
contain frequency marks in 50 kHz distance; the theoretical frequency
reading precision is some 10 kHz which is very good for an analog.
In practice, I found that the scale accuracy mostly ranged from spot
on to no more than 10-15 kHz off, with larger deviations only encountered
near the edges of the bands. This is really good for this kind of
Selectivity is not quite as good as on the ICF-SW7600G, but this seems
more a result of the latter's much more aggressive audio filtering,
since I found it to be almost as good as on the ICF-SW7600 (i.e. 5
kHz separation is quite decent, 9 or 10 kHz away it's almost perfect
unless the adjacent station is really strong), which uses the same
filter as the newer 7600G but with less tight audio lowpass filtering.
I found quite a bit of IF level hiss on the ICF-7601, which could
be reduced considerably by switching the tone control to NEWS.
is kind of hard to gather on this set, since absolutely everything
connected to it serves as an antenna, in best pocket radio manner.
This makes measurements with phones or AC adapter rather unfair. So
I had to resort to batteries, where another problem arises: My comparison
rig, the ICF-SW7600G, noticeably loses in sensitivity when run off
rechargeables. This could lead to the paradox situation of the ICF-7601
even being slightly ahead. All in all, I would say sensitivity is
good, up to par with the SW7600G or SW7600 when the band is peaked
up right (13m seems a bit weaker than some others on my sample). If
you happen to have an ICF-7601 with unexciting shortwave sensitivity
and know your way around radios, I'd suggest to obtain a copy of the
service manual and do an alignment.
to overload is one area where the 7601 doesn't fare too well. Particularly
the 31m band with its very strong signals in the evening (I'm in Central
Europe, which is notorious for high SW signal levels) overloads it
pretty badly so that only fully retracting the aerial helps. Attach
some phones or an AC adapter, and overloading starts again - did I
mention using the AC adapter cable as antenna is a real bad design
decision? (Not even the old Philips D1835 is that bad, and that's
a single conversion design!) Even on bands with medium signal strengths
you frequently hear some quiet whistle from an IM product. Well, at
least strong signals in one band don't affect the other ones. I did
notice some bleedthrough from a local FM station in the lower 31m
band; theories as to where this mixing product is created are still
being gladly accepted. The reference receiver does not exhibit such
rejection is fair on SW1 and excellent on the dual conversion shortwave
ranges. The reference rig does show some images, maybe due to 1st
IF leakage or 2nd mixer leakage.
from the IF level hiss in AM, I like the speaker audio of the ICF-7601,
which is just about a magnitude better than on the ICF-SW7600G. Listening
with headphones, you quickly notice there's quite a bit of bass expansion
going on with the tone switch in MUSIC position, which may be somewhat
tiring in the long run.
is everything but a battery hog. It should run many hours with decent
alkalines, and since it still works halfway well down to about 3 V,
batteries can be squeezed out quite well. I don't think rechargeables
are needed; if you do use them, be sure to keep a multimeter at hand
to check cell voltage in order to avoid deep discharge.
all, the ICF-7601 is a good choice for areas with lower signal levels,
where its sensitivity will be quite welcome; in a strong signal area
you may be annoyed by the mixing products. I'd consider it "tweaker's
paradise", since an alignment and FM filter change may help the
performance considerably. It sure is a fun rig, but please don't pay
insane sums for one.
A look at the ICF-SW7600
History and Concept
was produced from 1990 to 1993 and usually cost a bit more than US-$
200. It was the successor to the venerable ICF-7600DS (ICF-2003),
which in turn had been little more than an ICF-7600D (ICF-2002) with
different colors, the revolutionary little receiver from 1983. In
this case, the improvements over the older models were present but
not spectacular; rather a key design guideline seems to have been
effort and cost reduction while retaining or improving performance.
is clearly less complex than its predecessor, which can be seen not
only in the reduced number of PCBs but also the missing meter band
display and the lack of a clock display while the receiver is running.
It also shows a much higher degree of integration, which is not surprising
given it was introduced seven years later. Performance did not suffer
except for FM, in fact the audio is better and AM reception is generally
less noisy. Battery life particularly in FM could be noticeably improved,
a sideband choice for SSB was implemented and it was possible to do
away with the backup batteries.
is a PLL synthesized receiver tuning FM (in stereo via headphones)
from 76 to 108 MHz or 87.5 to 108 MHz with 100 or 50 kHz steps or
AM from 150 kHz longwave up to 29995 kHz shortwave continuously (on
most models), with 3 kHz steps on longwave, 9 or 10 kHz steps on mediumwave
(selectable via a switch in the battery compartment; doing so clears
the memories) and 5 kHz steps on shortwave. (Panasonic already offered
1 kHz steps in the RF-B65 back then.) On FM, it's the usual single
conversion design with a 10.7 MHz IF using two nominal 280 kHz IF
filters (and, BTW, an RF preamp FET), for the AM ranges it's a dual
conversion receiver with a 1st IF of 55.8425 kHz (a crystal filter
is used here) and a 2nd IF of 455 kHz (with a 6 element ceramic filter,
Murata SFR455I). A product detector is provided for SSB reception,
with two different carrier insertion frequencies to give preference
to the upper or lower sideband. For shortwave and FM, the telescopic
whip (about 69 cm in length) is used, LW and MW are received via the
front panel is neat and tidy: Speaker grille on the left, display
and buttons on the right. Above the display you can find the obligatory
tuning LED, below it there's a little table (with only mediocre readability)
showing the frequencies of the various shortwave bands. The display
itself shows the frequency if the receiver is on or the time if it
isn't, it also displays the number of the currently chosen preset
and indicates the operation of the sleep and standby timer functions,
if applicable. Right next to the display block sits the numeric keypad
with the keys for direct frequency entry; in the upper right there
is the sleep timer button (which turns off the radio after approx.
65 minutes) next to the on/off slider and switch. The latter functions
the same way as on the newer ICF-SW7600G - if the slider is in position
LOCK, the radio just shows the time and otherwise cannot be operated;
this is done to avoid accidental battery depletion. On the bottom,
five buttons are neatly organized in a row, with most of them having
a second time or timer related function when the receiver is off but
not locked: ENTER for saving memories (doubles as time set button),
BAND (doubles as standby timer set button) for band switching together
with the somewhat small pair of tuning keys next to it, the scan tuning
start/stop button (also used to enable the standby timer) and last
but not least the small key protect button which is used to lock the
buttons to avoid accidental frequency changes and such.
side of the receiver shows a DC in jack, headphone (stereo), line
out (mono), tape control and possibly external antenna (not on my
sample, silly postal regulations) jacks along with the attenuator
switch and finally the usual useless carrying pouch.
On the right side you can find the volume control slider (easier to
move than on the ICF-7601, though a smooth wheel is yet better), tone
switch (the usual NEWS/MUSIC choice), AM mode switch (selecting between
AM operation without fine tuning, AM with fine tuning, LSB and USB)
and the fine tuning wheel (which varies the frequency by about +/-
8...9 kHz on my sample, which is a bit much for my taste).
the top of the receiver contains a small light button for momentary
lighting of the display, and on the back you can see the battery compartment
for 4 AA (R6) cells and a rather big, stable flip-out stand with a
world time zone map on it. Phew.
I did like that you can cross rather large frequency areas quickly
thanks to the 5 kHz steps, some people may be annoyed by the chuffing
associated with quick tuning. (Continuous reception wouldn't make
much sense at least on AM, that's why the audio is muted upon retuning.)
I found the frequency entering concept with the separate buttons for
AM and FM to be somewhat weird, given the strict separation is not
mirrored anywhere else. Standby timer operation is limited to the
last frequency tuned to, unlike in later models which have separate
presets for this. Like in the 7600G, the scanning function on FM only
looks at signal strength and will stop a few times on a stronger station.
The receiver features the luxurious number of 10 presets which can
be randomly used for either FM or AM stations.
is nothing to write home about - sensitivity is noticeably lower than
on my 7600G in spite of the latter's modified filters with higher
insertion loss. The stereo threshold, however, seems to be lower,
but this might also be caused by the reference receiver's narrower
filters (I had them changed to 150 plus 110 kHz, which improved selectivity
dramatically) which cause higher distortion. Selectivity is not really
awe-inspiring either, as to be expected from the two 280 kHz barn
doors (but hey, it's better than with only one). I found what appeared
to be some sort of mixing product or spurious response from a strong
local station on 101.8 MHz on 96.5 MHz; this was not present on the
7600G. Overall, I'm not too surprised that at one time a new proud
owner of an ICF-SW7600 wrote that his old ICF-7600DS (or ICF-2003)
had been better on FM, apart from stereo of course.
AM ranges, it gets much more interesting. Sensitivity on mediumwave
proved to be near identical in both the ICF-SW7600 and ICF-SW7600G,
i.e. pretty good in this receiver class. This continued in the shortwave
bands when both receivers used the same AC adapter. With both running
off rechargeables, the sensitivity on the higher bands seemed to be
better on the older model at first, but in the end the sensitivity
varied far more greatly as a function of the supply voltage than between
the two. Antenna tuning could partly be improved on both models by
using the simple ADDX-PRE-1 antenna tuner / preselector. Mixing products
were a tiny bit harder to produce on the SW7600 than on the newer
model. Maybe this is related to the somewhat higher supply voltage
for the FETs in the 1st mixer and lower supply voltage for the preamp
FET, who knows. Image rejection proved to be identical in both models,
i.e. approx. 30-40 dB for +910 kHz. (Again, I had not expected this.
The measurements taken by Radio Netherlands suggested the SW7600 should
be noticeably worse.) Selectivity is not quite as good as in the 7600G,
which probably is related to audio filtering, since the IF filter
used is the same. The SW7600 is a tiny bit ahead of the 7601 (i.e.
5 kHz separation is quite decent, 9 or 10 kHz away it's almost perfect
unless the adjacent station is really strong), but lets much less
IF level hiss come through. The SW7600's frequency response is much
easier on the ears than the rather muffled audio of the 7600G.
works rather well, with nice, clean audio, though there is some distortion
on the first syllable with very strong stations (a rather common AGC
related problem). Unlike in newer models, SSB is not really sideband
selective - the LSB/USB setting only alters the frequency of the inserted
carrier so that more of the desired sideband is inside the frequency
range the filter lets get through, but you can still tune both sidebands
that way and may be bothered by stations on the opposite sideband
you did not want to hear. The lack of any sideband separation makes
ECSS (listening to AM stations in SSB) pretty much impossible (even
if you can get close to the carrier, the volume will be oscillating
with a beat tone), which is too bad because the SW7600 does not feature
synchronous detection yet (of course). The fine tuning range is rather
huge at some +/- 8...9 kHz on my sample, which not only makes clarifying
SSB stations a bit tricky (though certainly doable) but can also lead
to the listener finding himself more than 5 kHz away from the displayed
frequency - as if 5 kHz steps alone didn't make precise frequency
readings for SSB hard enough.
of speaker sound, the SW7600 can pretty much keep up with the ICF-7601
(i.e. it's noticeably better than the 7600G); the audio via phones
is rather nice with good bass, only the highs on FM are a bit lacking
in comparison with the 7600G and other equipment.
I have not evaluated battery usage - which is likely to be similar
to that of the 7600G - I can tell you that there is no battery warning
and that the receiver still plays decently on only 3 V. You'd better
have a voltmeter at hand when using rechargeables to avoid deep discharge.
the ICF-SW7600 is quite a nice older portable with good AM RF performance,
though its features are rather dated by now. Anyway, if you aren't
bothered by the once-typical AM distortion (meanwhile, I'm somewhat
spoiled by synch detectors, particularly the one in the AR7030) and
don't listen to SSB very frequently, this one might be for you. (To
be fair, the synch detector in the 7600G does not help a great deal
with selective fading distortion and rather prefers to unlock upon
severe fades. It is nice for sideband selection, though. AFAIK the
7600GR features improved synch detection.)
ICF-SW7600 trouble spots
for something completely different... failures, that is. You may know
that electrolytic capacitors are no infrequent trouble spots, and
they're even more likely to be if they aren't treated properly. The
filtering cap in the DC/DC converter that generates +15 V - C127,
a 22µF 6.3 V part - is such a case. The DC/DC converter operates
at a rather high frequency of almost 2 MHz, and that poor cap has
to take all the ripple it generates, which heats up the thing and
leads to faster aging in the end. Later models contain a small ceramic
cap in parallel, which takes care of the high-frequency ripple. Symptoms
of C127 failure are a PLL that only locks slowly or even fails to
lock with a noise similar to that of a machine gun (which is caused
by the PLL unlocking upon a voltage drop on the +15V line which in
turn is caused by the DC/DC converter being unable to supply enough
current). An underperforming C127 may also cause trouble on FM alone,
which may be remedied by exchanging C69 (Vcc buffering cap for the
CXA20111, 220 µF 4 V) - apparently the current draw from the
DC/DC converter is largest on FM because of the varicap diodes used
for tuning (otherwise +15V is only used for PLL related functions).
I suspect most frequently used ICF-SW7600s will face C127 related
problems in the long run. Problem is, you have to be pretty good at
SMD stuff to repair this.
my Sony 7600 series page for more details (opens in new window).