Re: SRF-M37V and SRF-M37W-Performance differences?


Hi Mike

Glad that you go the M37V fixed up - I wasn't aware that Radiolabs did
filter upgrades for individual units! Not sure where you're at, but here
in the Seattle area, it makes all the difference on the M37V.

The published Sangean DT-400W mod uses the next-narrower filter, the 3.0
khz HW version, so it is a little tighter yet, and I am contemplating
putting an HW on my other M37V. Would you mind telling me/us what
Radiolabs charges for an individual job like this?

Kevin S
Bainbridge Island, WA

Kevin (and all)

Just received my upgraded M37V from Radiolabs. I must say, while it may
not be up to fishing out splits from across the ocean, the nominal 4.5 KHz
Euroquartz LTS450GW makes the difference between "unuseable" and "very
nice" in my high RF environment near several MW transmitters. This was a
radio I really wanted to like but ended up being thrown in the bin because
of its "barn door" selectivity. It's the same basic size as the SRF-59 but
more sensitive, and now comparably selective.

--- In ultralightdx@..., satya@... wrote:

Hi Alex/All:

I have both a stock and a re-filtered M37V. The selectivity on the
re-filtered (with the LT450GW) is VERY good, noticeably better than the
not-too-shabby SRF-59 and almost that of the stock Eton e100. The stock
M37V is an absolute barn door, so it turns a Turkey into something of an
eagle. As Gary mentioned previously, it is now an Unlimited class
Ultralight, but it really becomes a great little radio.

As Steve Ratzlaff mentioned earlier, these little filters cannot be
expected to perform like the Murata narrow filter, but it is still a
improvement and an excellent domestic DXing filter choice. It even
dabbles in split frequencies: at the beach this past Tuesday morning,
M37V was able to get good barefoot readability on 774-JOUB from Japan
signals were sufficient, keeping strong stations on 770 and 780 at bay.

To change from 9 to 10 khz, first turn the unit off. Power and Clock
the buttons across the top. First push and hold Clock, THEN press and
hold Power, and hold both for about 5 seconds. Eventually a 9 or 10
flash on the screen, indicating to which tuning increment you have just
switched. Those 5 seconds seem an eternity...

Hope this helps - Kevin S
Bainbridge Island, WA

Hi Alex,

Actually even replacing the horrendous IF filter in the SRF-M37V with
the modest 450 kHz upgrades would place the radio in the "unlimited"
Because of this, fanatical tinkerers do everything possible to boost
performance-- premium filters, Slider loopsticks, and/or large
antennas. But the unique thrill of receiving rare DX on a stock
Ultralight is
still a big attraction, even for me. The Sangean DT-400W, Sony
E100 and C.Crane SWP stock Ultralights are very thrilling to take
DXpeditions, and can receive many TP's when conditions are right.

The SRF-M37V does have a procedure for switching between 9 kHz and 10
band tuning steps, and I'm sure that someone on the list can tell you
it (sorry, but my own manual seems to have disappeared, also). In the
days of the Ultralight boom (December 2007), the radio was one of the
popular digital Ultralights, despite the barn-door selectivity.

73, Gary

In a message dated 4/2/2009 12:38:21 P.M. Pacific Daylight Time,
rifleman336@... writes:

--- In _ultralightdx@ultralightdxult_
(mailto:ultralightdx@...) ,
D1028Gary@, D1

Hi Alex,

Whether the 450 kHz filter modification would be useless or not
depends on the type of DX you pursue.

For domestic DXers looking for a little more sensitivity, the
may help out somewhat. But for 9 kHz-split DXers chasing
to strong domestic stations, these modest 450 kHz filters are not
provide any significant help. Both Steve and I enjoy this type of
DXing, which is probably why we are more demanding than domestic
evaluating filter performance.

We also have probably been spoiled by the phenomenal performance of
kHz Murata "K" filter upgrades in the Slider E100's, which routinely
reception of weak TP's only 2 kHz away from strong domestics. Other
filters seem
very lame, in comparison.

73, Gary DeBock
Almost sounds like grounds for using a off board DSP filter, and a
antenna for more directivity. Ofcourse that throughs it in to the
unlimited class. Bummer!!! :>(

BTW, How do you listen to 9KHZ stations when the M37's are 10 KHz
increments. I've lost the manual is their a hidden switch or a


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