Hi Richard:

Gary DeBock tried a couple places on-line who claimed to have M37V service
manuals, but no one ever actually sent him the manual. Not sure how much
he spent on the effort, but there appears to be no such manual readily
available. Now that Sony is coming out with the M37W model, perhaps Sony
will reissue the manual?

My M37V has weather band as well, and it appears to do fine picking up WB
here in the metro Seattle area. I haven't tried it out in a more distant
area, though.

73 - Kevin S
Bainbridge Island, WA

Hi Stephan:

Gre aus Amerika! Ich habe Ihre Artikel ber die 7600GR geniessen.

False alarm! I forgot that the M37V uses a 450 khz filter, and so the
images are only 900 khz away. Sure enough, this morning my neighborhood
stations at 1590 and 1680 are solidly represented on 690 and 780, and so
the image problem is still there. I too was wondering how IF filtering
could solve an RF stage problem...

Sorry for the confusion!

73 - Kevin S
Bainbridge Island, WA

--- In ultralightdx@..., "dhsatyadhana" <satya@...> wrote:

Hi all:
Jim Kenny and I were talking on the phone and each pulled out our M37V
with a 4.5 khz retrofitted filter installed. Both of us realized that,
unlike the stock M37V, there were no images from strong locals (i.e.,

phantom 680 signal from local 1590, etc.). I then turned on my Sony
7600GR, and the images from my strong locals were blanketing the dial,
but nothing on the M37V!

Do keep in mind that the '7600GR with its wideband MW/LW
frontend will be more easily overloaded by strong AM
locals than a set with frontend tuning. (Its image
rejection is no greater than on shortwave, i.e. an
estimated 30..40 dB, for the same reason.)

But in any case, improved image rejection with a better
IF filter is a puzzler. Image rejection should be a
function solely of the frontend, i.e. RF tuning and mixer
(or, for most sets, RF tuning only, as regular mixers
have no inherent image rejection).

(A 680 kHz response from 1590 definitely is an image
if we're looking at a single conversion set with the LO
running above the tuned frequency - as it's normally the
case - and an IF of 455 kHz.)

Depending on achieved Q (and thus ultimately parts
quality), image rejection near the bottom end of MW for
sets with a single tuned IF circuit is about 30 to 50 dB.
It drops quite a bit towards the high end, but as there
are no strong signals directly above the band, this is
not an issue.

Anyway, I fail to see how the IF filter would play in
here. It can't really be spurious responses either.

Hmm. *scratches head*

Stephan

Has anyone performed an alignment of a M37? If so, could you share
with us how to do it?

Because I have three of these little receivers, I decided to
disassemble the least sensitive one. After removing four screws from
the back, you have to be careful with the clips holding the
logic/display circuit board in place. They are easily broken,
especially the one over the battery compartment. Also a short wire
runnig between the two circuit boards needs to be unsoldered. It's in
the lower left hand side, near the DX/local switch.

But I don't know where the adjustment points for alignment are
located. And I don't want to rely on guesswork.

I really enjoy using these little receivers, whether for general
listening or DXing. I always carry one (or a SRF-M35) with me to
sporting events. They fit into my hand just right and, in my opinion,
have a decent battery life. True, strong signals tend to spill over to
adjacent channels, such as local KFXY-1640 is heard from 1620 to 1660
kHz during the day. I assume this can be corrected somewhat with
tighter filters. So far I haven't found the images some others have
reported. However, I do wonder about Sony quality control because the
sensitivity on my three sets varies widely with the newer M37W being
the best. It's amazing how well the five centimeter antenna pulls in
signals. Its nulling ability is excellent.

The only real disappointment I've found is the weather band - it's
useless. I live in what is called "tornado alley" and the M37W's are
often sold locally (especially by Wal-Mart) as weather radios. It's
definitely false advertising.

Again, if anyone knows how to align the M37, please tell the rest of
us how it's done. It's a readily available, affordable ULR with DX
potential.

Hello Richard and Kevin,

 

     Because of a timing quirk, the SRF-M37V is one of the very few Ultralights that I haven't yet aligned.  It was part of the "Round One" Shootout posted on dxer.ca in late December, before I routinely started to align Ultralight radios prior to shootout competitions.  I know that local Puyallup, WA resident (and filter guru) Guy Atkins has done an alignment on an SRF-M37V, using instructions that I provided for a "quick and dirty" alignment on any AM portable without a service manual.  Perhaps he will read this, and share his experience. 

 

     For the benefit of those brave souls eager to align their Ultralight radio without a service manual, the "quick and dirty" alignment instructions are given below.  Proceed at your own risk, and be advised that some Ultralights (like the SRF-59) have a nasty reputation for inducing extreme regret in careless tinkerers.

 

1)  Remove the back cover to allow access to the loopstick.  Remove all wax binding the coil (or movable coil, if there are more than one) to the ferrite bar.  Ensure that the coil may be slid .25" either way, on the ferrite bar. NOTE:  The ICF-2010 and ICF-SW7600GR loopsticks cannot be aligned for sensitivity.

 

2)  If batteries are disconnected by the removal of the back panel, run jumpers and turn on the radio.  Tune in a WEAK station on the lower end of the dial (anything from 570- 630 kHz will do).  Slide the loopstick coil to peak the weak signal, and temporarily secure it with tape on the ferrite bar. NOTE:  This step will usually provide a major improvement in Ultralight radio sensitivity, and is quite easy to accomplish.

 

3)   Tune the radio to a WEAK station anywhere from 1360-1440 kHz.  On an analog radio, locate the 1400 kHz alignment trimmer (almost always located on the main tuning capacitor component) by attempting to peak the weak signal on the various trimmers, always after carefully noting the original position of the trimmers and returning to these exact positions, should the attempt prove unsuccessful.  The correct trimmer will peak the weak signal, but not shift the frequency to allow reception of adjacent stations.

    On a digital radio (assuming it is not the DT-200V, DT-200VX, DT-400W, DT-210V, DT-220V, E100, or C.Crane SWP for which we already have a procedure), the hobbyist will need to locate the correct 1400 kHz trimmer capacitor on the RF circuit board, usually adjacent to other trimmer capacitors for different bands.  Using the trial and error method described above for analog units, attempt to peak the weak signal by adjusting various trimmers, always after carefully noting the original position of the trimmers, and returning to these original positions if the peaking attempt is not successful.  The correct trimmer will peak the weak signal, but not shift the frequency to allow reception of adjacent stations.  NOTE:  AM IF transformers will behave exactly like 1400 kHz trimming capacitors, in peaking the weak signal. This is favorable to accomplish, since improvements in AM IF transformer peaking will increase the AM sensitivity.  For this reason, any component with an appearance like an IF transformer should have adjustment attempted, as described above.  The cumulative affect of multiple IF transformer adjustments can provide astonishing sensitivity improvements in some vintage radios like the TR-6400, 6R-33, etc.

 

4)   Return to the loopstick and attempt further peaking of the movable coil on the low-band (570- 630 kHz) weak signal by shifting the coil along the loopstick. If no further sensitivity improvement is noted, secure the coil in this position with wax, tape or a spot of woodworking glue. If a major improvement is noted, repeat Step 3, then repeat this step and secure the coil on the loopstick.

 

5)  Reassemble the radio, and enjoy the full sensitivity that the engineers designed for your particular model.

 

                             73,  Gary DeBock    

 

     

    

Sorry for the horrible english in the last message, it seems I need some
coffee...

string = strong
could be fix = perhaps fixed

:)

--hg

Hi group,

yesterday I was playing with Redsun RP300. It has an odd behaviour, if
you tune 10-20KHz away from a string, local station, you can still
listen to a demodulated and readable audio a little bit more 'trebly'.
It's like a 'leakage' between the RF/AF stages. I would consider it
normal if it was, say, 1-3KHz... but 20KHz is too much!

On the other hand E100 works just as one expect, if you tune about 5-7
KHz (or more) away from a local station you heard the splatter, kind of
noise non-readable.

For a moment, I thought the filter replacement could be fix some kind of
'signal leakage'.

--hg

--- In ultralightdx@..., "dhsatyadhana" <satya@...> wrote:

Hi all:

Jim Kenny and I were talking on the phone and each pulled out our
M37V
with a 4.5 khz retrofitted filter installed. Both of us realized
that,
unlike the stock M37V, there were no images from strong locals (i.e.,
phantom 680 signal from local 1590, etc.). I then turned on my Sony
7600GR, and the images from my strong locals were blanketing the
dial, but nothing on the M37V!

Do keep in mind that the '7600GR with its wideband MW/LW
frontend will be more easily overloaded by strong AM
locals than a set with frontend tuning. (Its image
rejection is no greater than on shortwave, i.e. an
estimated 30..40 dB, for the same reason.)

But in any case, improved image rejection with a better
IF filter is a puzzler. Image rejection should be a
function solely of the frontend, i.e. RF tuning and mixer
(or, for most sets, RF tuning only, as regular mixers
have no inherent image rejection).

(A 680 kHz response from 1590 definitely is an image
if we're looking at a single conversion set with the LO
running above the tuned frequency - as it's normally the
case - and an IF of 455 kHz.)

Depending on achieved Q (and thus ultimately parts
quality), image rejection near the bottom end of MW for
sets with a single tuned IF circuit is about 30 to 50 dB.
It drops quite a bit towards the high end, but as there
are no strong signals directly above the band, this is
not an issue.

Anyway, I fail to see how the IF filter would play in
here. It can't really be spurious responses either.

Hmm. *scratches head*

Stephan

Hi all:

Jim Kenny and I were talking on the phone and each pulled out our M37V
with a 4.5 khz retrofitted filter installed. Both of us realized that,
unlike the stock M37V, there were no images from strong locals (i.e.,
phantom 680 signal from local 1590, etc.). I then turned on my Sony
7600GR, and the images from my strong locals were blanketing the dial,
but nothing on the M37V! I even tried putting a Terk Loop up to it,
and the true 680 station just came in better.

So, it appears that with a decent filter, the horrid selectivity and
images problems with the stock unit are done away with! Not sure if it
does anything for spurs such as those that Gary DeBock finds at his
QTH. I will have to check tomorrow when spur DXing conditions are at
their peak :-).

I am speculating that, as the TV band goes away, M37Vs will be at close-
out prices pretty soon. With 5 memories and 9 khz tuning, perhaps not
a bad investment! The DX challenges that remain for this little guy
are working around the modest selectivity from the native micro-
ferrite, and the inability to tune 1 khz off like the Eton e100 can.

73 - Kevin S
Bainbridge Island, WA

Hi Kevin,

 

     The Sony SRF-M37V is indeed a puzzle--  an Ultralight with fairly decent sensitivity but barn-door selectivity, in stock form. Allen Willie in Newfoundland has used it to receive more new TA countries than all other Ultralight DXers combined, but for most of us, it's just not as competitive as an SRF-T615, E100 or DT-200VX.

 

     During a recent visit to Oregon, I noticed the new SRF-M37W model for sale at a Fred Meyer, so I picked up one for the Ultralight Summertime Shootout.  It looks almost identical to the SRF-M37V, but the TV audio coverage has been replaced by weather band coverage (like the DT-200VX and DT-400W).  Price was $34.95, like the old SRF-M37V.  It hasn't been tested out yet, but if Sony improves the AM IF filter in this new model, it would make a huge difference for us (even though it's probably wishful thinking).

 

     The 450 kHz IF of the model makes some decent filter modifications possible (as you and Jim have experienced), but the E100's 1 kHz tuning steps provide a huge advantage for 9 kHz split-frequency DXing, to chase TP's and TA's.  The 455 kHz IF of the E100 also makes installation of some VERY effective IF filters possible, such as the Murata CFJ455K5 ceramic filter.

 

     Your modified SRF-M37V's would make a very interesting project for a large loopstick transplant, Kevin.  We have discovered that whenever a selectivity boost is combined with a major sensitivity boost, an Ultralight suddenly becomes an Ultra-effective DX chaser.

 

                                                                    73, Gary

 

       

Hello Guys,

 

     We are thrilled at the rapid growth of Ultralight radio interest among the AM-DX community, and very happy to note that our Yahoo group site now has 59 members.

 

     We also extend our warmest welcome to new members markjtaylor73, darobin12001, radioman69uk, sgrossklass, flemingchris, and rjbrjb20022002.  Our worldwide enthusiast group is united by interest in AM-DXing with relatively inexpensive pocket radios, and we all stand ready to assist you in any possible way concerning technical questions, equipment reviews, and high-performance modifications.

 

     Please also take advantage of the numerous Ultralight radio-related files posted on dxer.ca, truly a treasure trove of helpful information for all DXers interested in the excitement and challenge of pocket radio AM-DXing (for which we again express our gratitude to Colin Newell).

 

73 and Best Wishes,

 

Gary DeBock (N7EKX)

Puyallup, WA USA 

 

 

I finally opened the case of my Mini 300 to take a look at what's
inside, but made no adjustments. My guess is alignment would similar
to the E100.

To disassemble, first remove three screws (two in the battery
compartment) and slowly lift the back from the bottom slowly to detach
it from a hook at top right (from the back). The hook could be broken
if not done correctly. Once unhooked, the back is free to set aside.

Now remove the two screws holding the main circuit board to the front
of the case. Below it you will notice a second circuit board attached
to the front case above the speaker. It's the frequency
counter/display circuit and there's no reason to remove it.

There is an approximately 5 x 0.7 cm. (1.9" x 0.27 ") ferrite bar
antenna at the top of the main circuit board. It looks like a shorten
version of the one in the E100. Like the E100, the antenna coil is
held in place with wax, so the 600 kHz adjustment should he easy. I
didn't identify the 1400 kHz adjustment point - it's one of the eleven
on the front of the circuit board.

To reassemble the receiver, first secure the main circuit board to the
case front ensuring the band switch is in its correct position. Then
hook the case back to the front checking to see the battery
compartment springs fit back into place. Finally replace the three
screws holding the two halves together.

My opinion is the tuning control on the Mini 300 keeps it from being
used for serious DXing. It's extremely tricky to use and takes a very
practiced thumb or forefinger to get it right on the desired
frequency. A 3.5 (1.4") cm. tuning control wheel is coupled directly
to a small variable capacitor. It would probably benefit from some
type of venier tuning apparatus.

Richard Allen

At 12:47 PM 8/6/2008, ALLEN WILLIE wrote:

Hi Guys,

Caught a couple new ones last night and early this morning

1530 khz - 7:44 UTC 8/6/08 - XEUR Mexico City, Mexico w/ mexican style
music and "Radio Fiesta " ID between songs, announcer in Spanish ; good
(My first Mexico station on Ultralights)

Another Good One Allen....and all I can say to that is......OLE!!!!

Wish I could hear that one....and I'm a lot closer to it than you are!!

73...ROB.


Robert S. Ross VA3SW
Box 1003, Stn. B.
London, Ontario
CANADA N6A5K1

Antique/Vintage Radio Enthusiast
Amateur Radio Stations VA3SW/VE3JFC

Defy Physics.....Play Table Tennis!! (Ping Pong with an Attitude)
«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»¥«¤»§«¤»¥«

Hi Guys,    Caught a couple new ones last night and early this morning   1530 khz - 7:44 UTC 8/6/08 - XEUR Mexico City, Mexico w/ mexican style music and "Radio Fiesta " ID between songs,  announcer in Spanish ; good (My first Mexico station on Ultralights)   1539 khz - 23:42 UTC 8/5/08 - RTV de Djibouti , Dorale w/ arabic commentary and fast paced arabic pop vocals; fair     73 Allen Willie St. John's, Newfoundland SRF-M37V barefoot

---

All new Yahoo! Mail - Get a sneak peak at messages with a handy reading pane.

John,

I recently purchased my E100 through the offer on the DXer.ca homepage.
The radio actually came from the Shortwave Store, which I am guessing is
the U.S. side of Durham Radio.

Anyway, I checked my E100 against your photos. Mine has the fancy
script "eton" lettering (the old version) and has the serial number
(E10-0) 610029065. So, I guess mine is one of the "good" ones.

Thanks for the alert!

73,

Steve N5WBI
Houston TX

RED ALERT:  Friday, I opened up my last unmodified E100, planning to do the Full Monty, align, replace the IF filter and make capable of using both outside antennas and larger ferrite bars. When I popped the back, I almost had a heart attack!  IT IS COMPLETELY DIFFERENT INSIDE!!!  Different boards, different components, different design of the ferrite loopstick coil (much like the SRF-59!)  The parts count is also lower and there seem to be efforts to reduce costs in several areas.  The only thing that looks better is the IF Filter.... this E100 reads more nearly on, but is about 500 hertz low.

When Gary writes his review of the E100 for our series on this wonderful little radio, I'm sure that he will test this particular unit against our more normal ones. Until then, I can't say for sure, but my gut feeling is this "NEW" E100 model is less of a radio than any of our "OLD" ones. Here is what I know for sure:

1. It can't be aligned to peak performance because each of the (2) coils on the ferrite bar is GLUED down.
2. It is a completely different RF design and uses a large major coil jointly with a smaller "tickler" coil. THEREFORE, none of our current ferrite bar replacement strategies can be applied to this new radio design... at least not very easily.
3. At this point, I have no idea whether our IF filter substitution would work in this new circuit. However, it appears that the IF is still 455, so it may work.... tho' why anyone would put a $50 filter in a radio that can't be aligned is not obvious to me.

In short, if you are thinking of buying an E100, I would suggest that you make VERY sure that it is not one of these new ones. At least that is the advice that makes the most sense right now.

I wanted to talk this over with Durham Radio before I went public with it. Since many of us, including me, had bought our radios there and since Durham has been such wonderful support to the radio hobbies for a long time, I wanted to see what they knew and gather a bit more information before sharing this with the community. Thanks to Rob Ross, I learned that Durham would not be open until today, so I contacted my co-authors Saturday and we did a quick project comparing serial numbers. Here are the results 

All E100 serial numbers begin E10-0 and the nine-digit number listed below

SORT By Serial Number
Owner- No     O/N Serial Number    Comments
G Atkins - #1    OLD 503011604
J Bryant - #1     OLD 504016168   Pur. May 08 JHB's Longwire Set
G. Atkins - #2    OLD 504019074
J Bryant - #2     OLD 504019367   Pur. June 08 Ferrite Set
J Bryant - #4     OLD 505023942   Pur. June 08 JHB pur. Parts Set
R Ross - #1     OLD 704029648    Pur. Durham April 08
G DeBock - #1 OLD 704029656    Pur. Durham April 08 w/Rob Ross Stock
R Ross - #2     OLD 704029682     Pur. Durham late July 08
K Schanilec      OLD 704029693    Anomalous Ferrite Loop stick maybe "NEW"?
G DeBock - #2  OLD 704030008    Pur. Durham June 08 Slider + CFJ455K5 Filter
G DeBock - #3  OLD 704030009    Pur. Durham June 08 Slider
J Bryant - #3     OLD 704030013    Pur. Durham June 08 (Fried by JHB)
J Bryant - #5  "NEW" 709030292   Pur. Durham late July 08

As you can see, my NEW and different model has a serial number substantially higher than any of the others in our small early inquiry. Happily, there are a few subtle external differences that can distinguish OLD and NEW, as well.  I'll insert one picture here.  If you cannot see this, there are several photos in our Photo area.




Today, I talked to "Jamie" at Durham, who was very helpful. I got the sense that they still have several hundred and he pulled a new case of twenty and looked in the battery compartment. The serial number was VERY safe, in the 504 or 505 series. I discussed how important the difference between the two sub-models is to us Ultralighters and he was quite sympathetic. I asked if they could possibly check the serial numbers before sales for those of us who request such and he indicated that they would try to help us, if we would request such at the time of purchase. Most helpful! Obviously Durham Radio is a "real radio company!"

If you are buying on EBAY, I think that you should make very sure that the radio pictured is the EXACT radio that is being offered. If it is so, then you can check the typeface for the difference in the two sub-models.... At least we hope that no new boards were put in old cases. Wow!

I would be happy to gather more serial numbers in the database and post it.  They are located in the battery compartment and easily accessed by removing the batteries. We are particularly interested in hearing from people who own radios in the 704 and higher series and would love to hear if anyone else has a set with the new elegant block lettered typeface.

I'll upload pictures of the interior comparison as well as the typeface to our Photo Area in a few minutes.



 

John B.
Orcas Island, WA, USA
Rcvrs: WiNRADiO 313e, Eton e1, Ultralights
Antennas: Two 70' x 100' Conti Super Loops, West and Northwest

Interestingly I was also thinking about the possibility of using a BFO
with an ULR this afternoon. I discovered an interesting article at
www.crystalradio.net/crystalsets/bfo/Mike_Tuggle_BFO_Article.doc a few
minutes before reading your post. It includes a BFO circuit that
someone might be able to adapt to an ULR - most likely the E100.

Richard Allen

Hi all:

One thing that ultralights don't have, by definition, is a BFO by
which a heterodyne may be heard to indicate that a weak station is
there. With the Sony 2010 or other communications receiver, tuning
slightly away from 774 khz (say to 775 khz) with the BFO on (i.e., in
SSB mode) will produce a 1 khz het which lets you know that JOUB-
Japan is there. Simply jumping up and down the dial by 9 khz will
conveniently produce a het to show that a TP/TA is present on a given
channel. This can serve as a "spotter" receiver to indicate when a
prize catch can be had on another receiver.

As discussed at http://www.qsl.net/vu2msy/listening.htm and perhaps
elsewhere, you can induce a beat frequency into your Ultralight with
another radio! This is easily done with two SRF-59's (and we all
have at least two of them...). For example:
1. Tune the listening receiver to a station at 730.
2. Place the BFO unit directly on top or underneath.
3. With the BFO unit turned ON, and volume all the way down,
tune it about 50 khz lower (i.e., to 680 khz or so).
The 50 khz IF on the SRF-59 means that, on the BFO unit,
a beat frequency of 730 khz is being produced in order to
tune in 680 khz.
4. Since the 730 broadcast signal on the listening unit and the
730 khz beat frequency on the BFO unit are now colliding with
each other, you should hear a fairly pronounced heterodyne!
5. Move the BFO unit around a bit to adjust the intensity of the het.

The 55-khz (or so) IF on the SRF-59 family works well, because you
can cover nearly the entire dial. For instance, tuning the BFO unit
to 525 khz (its lower limit) produces a beat frequency of around 580
khz, which can then be fed to the listening unit. Contrast this with
using a BFO unit with a 455 khz IF: the lowest beat frequency it can
produce is (455 + 525 =)980 khz, meaning that the listening unit can
only be tuned as low as 980 khz while still being able to take
advantage of the het production.

What I have noticed is that the Sony S5W, with its humongous RF
stage, puts out a huge BFO signal, which may be more convenient if
you are working the upper part of the band - you can be several feet
away and still pick up the beat frequency! As such, the enhanced RF
stage on a super-modified SRF-39 might make it a good BFO unit for an
Eton E100 listening unit.

On thing to watch - you will likely notice that sensitivity on the
listening unit goes down. What appears to be happening is that the
BFO signal from the BFO unit, when received on the listening unit,
causes the AGC on the listening unit to reduce the overall gain. In
other words, if the broadcast signal and BFO signal are about the
same, the AGC will cut the gain in half in order to keep what it
believes is a constant audio level. Therefore, judiciously place the
BFO unit a little farther away in order to keep the gain up while at
the same time still inducing a beat frequency into the listening
unit. Alternately, I suppose you could super-modify your listening
unit to switch out the AGC!

Being somewhat inland and not prone to getting up a 4:30 AM (lying
prone often seems preferable, and unlike John B. I don't have cats to
push me out of bed), I haven't been able to try this out with actual
trans-oceanic signals, and so I would be delighted if someone out
there (Alan in NF??) would give this a try to see how useful it is.

73 - Kevin S
Bainbridge Island, WA

Allen and Rob,

 

     The West Coast Ultralight TP Chaser group salutes Allen for his remarkable Transatlantic DX accomplishments with his stock Ultralights.  We should all be so lucky.

 

     Here on the Left Coast, we take our deviously modified E100's to the beach for a few mornings of DXing at the nasty hour of 0500, and if we are extremely lucky, we come away with a rare new Pacific country such as Fiji or Tonga (but usually end up just listening to the same old Aussiea and Kiwis over and over).  It's enough to make someone seriously consider immigration to The Rock (or more likely, seriously consider even more devious ways to modify the E100).

 

                                                                                       73,  Gary   

At 10:27 AM 8/4/2008, you wrote:

Hi Everyone,

Pretty good Transatlantic session last night, decent discernable audio on
just about every split frequency. Including a lot of middle east stations.

Managed to notch a few new ones also using the SRF-M37V barefoot

1341 khz - 00:51 UTC 8/4/08 - HUNGARY, R Magyar Katolikis, Siófok w/
religious talk in Hungarian, musical selections ; (good at times stronger
than the usual R. Ulster)
***NEW ONE *** New Country on ultralights also****


1539 khz - 00:22 UTC 8/4/08 - UNITED ARAB EMIRATES , VOA Relay Dubai, man
in arabic mentions of Afghanistan, mention Voice of America ; fair *** NEW
ONE ***

Allen Willie
St. John's, Newfoundland
SRF-M37V barefoot

Allen...You continue to amaze us all with your Superb Loggings of Trans
Atlantic Stations!! You have a set a standard that will be hard to
duplicate by any of us. Your continued efforts to Promote the Ultralight
DXing Hobby are appreciated by all who partake in this strange Subculture
of AM BCB DXing!!! You have done us all proud...and although it is now
expected that your loggings will be spectacular.....it still amazes what
you are able to hear from the THE ROCK!!

Keep up the great DX Allen........it will be interesting to see just what
is and isn't possible on an Ultralight!!

73...ROB.


Robert S. Ross VA3SW
Box 1003, Stn. B.
London, Ontario
CANADA N6A5K1

Antique/Vintage Radio Enthusiast
Amateur Radio Stations VA3SW/VE3JFC

Defy Physics.....Play Table Tennis!! (Ping Pong with an Attitude)
«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»§«¤»¥«¤»¥«¤»§«¤»¥«

Hello Guys,

 

     The Sony ICF-SW7600GR is compact digital SSB portable with reasonably good MW performance, using a stock 4.75" x .37" fixed-coil loopstick for the 530-1700 kHz frequencies.  At $134.80 plus shipping from Amazon.com (via Gigabargain), it has excellent Synch detector function for a portable, as well as decent shortwave performance.

 

     Having a sudden need for a very compact SSB-equipped MW portable to use as a "spotting receiver" for South Pacific DX targets during a short Ultralight Radio DXpedition to Grayland, Washington, I became intrigued with the idea of replacing the SW7600GR's stock loopstick with a 7.5" Amidon ferrite bar, wound with 40/44 Litz wire.  This combination of MW frequency-optimized ferrite and Litz wire has provided huge sensitivity gains not only in the SRF-39FP and E100 Ultralight models, but also in the larger ICF-2010 traditional DX portable.  Upon checking the stock SW7600GR loopstick, it was found to be a smaller-sized copy of the ICF-2010 loopstick system, having a fixed (non-alignable) larger coil and a smaller tickler coil, to optimize spurious signal rejection.

 

     The SW7600GR loopstick was easily replaced with a 7.5" x .5" Amidon ferrite bar-based antenna, wound with 40/44 Litz wire to match the 983 mh inductance of the stock main coil.  The sensitivity improvement was very dramatic, boosting the weak-signal performance of this compact portable past that of a stock ICF-2010.  This was a total reversal of its performance prior to the modification, in which the SW7600GR was clearly inferior to the stock 2010 on all MW frequencies.

 

     At Grayland, the newly hot-rodded SW7600GR performed very well as an SSB "spotting receiver," with different TP station frequencies stored in memory, easily accessed by pushing single buttons.  SSB carrier strength of the "targets" could be quickly checked, and the direction of the received signal could be easily determined by the new loopstick's excellent nulling ability.

 

     On the domestic frequencies, the newly modified SW7600GR provided lots of sensitivity, with easy loggings of KPUA-670 and KGU-760 in Hawaii.  For the 9 kHz split targets in the South Pacific, however, the modified SW7600GR's sensitivity alone wasn't quite adequate to keep up with the modified Eton E100 Ultralight, which had a Murata CFJ455K5 premium ceramic IF filter installed (the same narrow filter as in the Eton E1).  The modified E100 could split off Fiji-639, Tonga-1017, 2ZB-1035 and 2YA-567 significantly better than could the modified SW7600GR, which had to contend with more domestic slop.

 

     Despite this, the compact Sony's function as an SSB "spotting receiver" was excellent, and it directed the AM-mode only Eton E100 to the "hot" frequencies very well.  9 kHz SSB carrier strength can usually be checked even in the presence of domestic splatter, and the SW7600GR was great for this purpose.

 

     For domestic DXers, this modified ICF-SW7600GR would provide a great sensitivity improvement over the stock model, for a very reasonable cost in parts (under $30 for the ferrite bar, Litz wire and other items).  The modification is easy to perform, and the unit remains very compact (a photo is on the Ultralightdx Yahoo group site in the "Roll Your Own DXing Monster" album).  Nulling ability is excellent, and the loopstick's external mounting provides extremely quiet reception compared to the stock antenna, crammed as it is inside a cramped cabinet next to the SW whip antenna.  The full modification article should be written shortly, for those interested in this impressive performance upgrade. 

 

     For serious 9 kHz split-frequency DXers, however, a premium IF filter upgrade would be very helpful in chasing TP's and TA's next to domestic splatter.  The good news is that with an IF of 455 kHz, the ICF-SW7600GR can be modified with the same premium ceramic filter that has transformed the tiny E100 into a DXing sensation this summer.  Well, there's always a nice-to-do project that is on the drawing board...

 

73,  Gary DeBock