Hi Kevin & Gil !

Thank you both for your attention !

I just read the SRF-M37 mods and saved the photos and filter indications
of the Ebay seller.

I liked to know the mod is possible but ive a simple question : Im eying
the Velco Electonic table with all the filters and i dont understand why
the LTS-450-GW was the choosen instead of LTS-450-ITW, having this filter
a best selectivity in 6dB (+/-2.0Khz), while LTS-450-GWs selectivity is
(+/-4.5Khz) ?

Is there some possibility to install ITW instead of GW filter or is is
there some techinical limitation to install ITW ?

Milton
Curitiba city
Parana state
Brasil



2c.
Re: SRF-M37V and SRF-M37W-Performance differences?
Posted by: "satya@..." satya@... dhsatyadhana
Wed Apr 1, 2009 8:09 pm (PDT)
Hi Milton:

Sorry, it was done by someone else, so I'm afraid I don't even know
what
it looks like inside.

Hey Gil Stacy - do you remember how the filter is changed out???

Kevin S
Bainbridge Island, WA

> Hi Kevin !
>
> I also have a SRV-M37V and i have an intention to change the filter.
>
> I have a technical background to make this change.
>
> Do you have the source of this changing information ?
>
> Milton
> Curitiba city
> Brasil
>

Hi Michael,

Thank you for your work in developing the LTM450HT filter modifications for
the Sangean models, and for uploading the information to DXer.Ca.

Steve and I were working toward the specific goal of transforming the 450
kHz Sangean models into very effective 9-kHz split DX chasers for transoceanic
reception, such as we had successfully accomplished with the 455 kHz Eton
E100 model last summer. We knew before commencing the work that 450 kHz
"consumer-grade" filters are not comparable with the premium Murata CFJ455K5 filters
we used in the E100, but we wanted to try anything available, since a vastly
improved Slider loopstick had already been successfully transplanted into the
DT-200VX (as described in a DXer.Ca article), greatly boosting the model's
sensitivity.

Unfortunately, the project was probably doomed from the start, due to
unrealistic expectations. If you have ever used one of the premium 455 kHz Murata K
filters for transoceanic DXing, you will probably understand how quickly a
DXer can become spoiled with the phenomenal performance. Anyway, we never
meant to be dismissive of your LTM450HT modification for domestic DXing, and hope
you will understand that our 9 kHz-split DXing performance requirements are
far more demanding than those of the average DXer. We regret any impression
to the contrary.

73 and Best Wishes, Gary DeBock


In a message dated 4/2/2009 6:50:21 P.M. Pacific Daylight Time,
knallebo@... writes:

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

Before carrying out a mod you have to determine what you expect.

As the author of the DT-210L & DT-400W filter mod articles, I find the
comment that the mod is 'not worth all the effort' frankly incredible!

The mods were not offered as a panacea for turning these radios into
9/10kHz-split DXers machines. That would be impossible with the type
of filters (6kHz @6dB BW) used. Rather, the articles were offered in
the spirit of improving the usability of these radios in the domestic
context. The give-away line in my article was 'the intrinsic quality
of the audio remains.' By implication therefore, the mod filter is not
especially selective merely an improvement on the original.

The moral of the story is to make sure any ULR you intend to mod for
9/10kHz-split DXing has a 455kHz IF system and the ability to tune in
at least 1kHz steps or better. 450kHz IF radios are a waste of time
since narrow filters with a good shape factor are simply unavailable.

Whilst agreeing fully with the remark by Steve about skirt selectivity
and filter size, I have to ask:

Was the LTM450HT filter used? Nothing else will bring much improvement
except for a LTM450IT or even narrower filter, if you could find one.
The 'T' suffix in the filter model number is important since these
have superior skirt selectivity over those without the 'T' suffix.

Living here in the UK I frequently wonder what North American DXers
mean by a 'high RF environment'mean by a 'high RF environment'<WBR>. Among
of one 150kW & two 400kW MF transmitters & less than 1 mile of two 1kW
MF transmitters.

The DT-210L & DT-400W filter mods have transformed the reception
capabilities of these radios close to these powerful signals. Before
the mod, five (9kHz) channels either side of the frequency of one of
these strong locals were rendered useless for weak signal reception by
the original filter. After the mod I am able to hear weak signals on
the immediately adjacent channels (±9kHz) with only a small level of
adjacent channel interference.

Perhaps your RF environment(Perhaps your RF environment(<WBR>s) are not r
that is the reason you are not reaping the reward from the mod?

--
Michael Slattery
Sheffield, UK

Hi Michael,

Thanks again for your filter modification work, and your kind comments.

Actually both Guy Atkins and Steve Ratzlaff are far more experienced in
filter modification work than me, and I've simply managed to learn a few things
by having the privilege of working with them. My own contribution to the ULR
experimentation efforts here has been in loopstick improvements, in attempts to
make these tiny radios as sensitive as possible. If you are a member of MWC,
you may have seen a few of my fanatical loopstick articles that were
published in Medium Wave News.

About a year ago, I learned the harsh lesson that sensitivity improvements
alone were not going to make a major difference in chasing 9 kHz-split DX with
Ultralight radios. A small radio needs both a major sensitivity boost and a
major selectivity boost in combination, to make a radical improvement in
overall performance.

By a tremendous stroke of luck, one of the primary filter experts in the USA
(Guy Atkins) lived right in my small home town, here in Washington state.
Our cooperation last summer (along with contributions by John Bryant) produced
the first major breakthrough in ULR 9 kHz-split DXing performance, the fully
modified Eton E100. Steve and I were attempting to create something similar
with the DT-400W in the winter, but despite our unrealistic expectations, we
ran up against the harsh reality that all the commercially available 450 kHz
IF filters are mediocre for transoceanic DXing.

73 and Best Wishes,

Gary DeBock


In a message dated 4/3/2009 7:45:52 P.M. Pacific Daylight Time,
knallebo@... writes:




Hi Gary :)

Thank you for your kind thanks for my mod articles. I'm sorry that
some folk may have been misled into thinking the selectivity
enhancement would be much greater.

There was not that much effort expended in development. On obtaining
both the DT-210L and the DT-400W I was extremely disappointed by the
very poor selectivity. My gut reaction was that I had to do something
about it and whilst I was 'at it' I took a few photos reckoning that
it may be of use to someone somewhere!

I'm fully aware of the performance provided by the premium filters you
and others have been using for 9-kHz split DX chasing. I've used them
myself in my AOR AR7030 for many years but not yet in a ULR.

Some thoughts: I know you and Guy Atkins have spent quite some time
developing filter mods for various ULRs. I wonder whether it might be
worth investigating the Collins Low-Cost Series of mechanical filters
that have a superior passband ripple to ceramic filters possibly
enhancing the intelligibility of reception. Expensive, but when only
the best will do. Inrad have a 2kHz 8 pole variant:
<_http://www.inrad.http://www.ihttp://www.inrht&cat=5&<WBR>p_
(http://www.inrad.net/product.php?productid=19&cat=5&page=1) >
or a 2.3kHz 10 pole variant:
_http://www.inrad.http://www.ihttp://www.inrht&cat=5&<WBR>p_
(http://www.inrad.net/product.php?productid=18&cat=5&page=1)

In the DT-200VX and DT-400W, if space cannot be found for the filter
within the case maybe one of the AA cells could be disposed of to
create a space for the installation the filter. The remaining AA cell
bay could then be loaded with a 3.6V Lithium AA cell.

Thanks once again for your consideration.

73

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 huge
improvement and an excellent domestic DXing filter choice. It even
dabbles in split frequencies: at the beach this past Tuesday morning, the
M37V was able to get good barefoot readability on 774-JOUB from Japan when
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 are
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 will
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 one
of
the modest 450 kHz upgrades would place the radio in the "unlimited"
class.
Because of this, fanatical tinkerers do everything possible to boost
performance-- premium filters, Slider loopsticks, and/or large directional
external
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 SRF-T615,
Eton
E100 and C.Crane SWP stock Ultralights are very thrilling to take along
on
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 kHz
AM
band tuning steps, and I'm sure that someone on the list can tell you
about
it (sorry, but my own manual seems to have disappeared, also). In the
early
days of the Ultralight boom (December 2007), the radio was one of the
most
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
probably
depends on the type of DX you pursue.

For domestic DXers looking for a little more sensitivity, the
modification
may help out somewhat. But for 9 kHz-split DXers chasing transoceanic
DX

next

to strong domestic stations, these modest 450 kHz filters are not going
to

provide any significant help. Both Steve and I enjoy this type of

transoceanic

DXing, which is probably why we are more demanding than domestic DXers
in
evaluating filter performance.

We also have probably been spoiled by the phenomenal performance of the

455

kHz Murata "K" filter upgrades in the Slider E100's, which routinely
allow
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 loop
antenna for more directivity. Ofcourse that throughs it in to the
ultralight
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 "keyboard
trick"?

ALEX N8UCN/KOH8IG






**************Worried about job security? Check out the 5 safest jobs in a
recession.
(http://jobs.aol.com/gallery/growing-job-industries?ncid=emlcntuscare00000003)

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.


http://www.euroquartz.co.uk/pdf/ceramic-lts-450w.pdf


--- 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
huge
improvement and an excellent domestic DXing filter choice. It even
dabbles in split frequencies: at the beach this past Tuesday morning,
the
M37V was able to get good barefoot readability on 774-JOUB from Japan
when
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
are
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
will
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

one

of
the modest 450 kHz upgrades would place the radio in the "unlimited"
class.
Because of this, fanatical tinkerers do everything possible to boost
performance-- premium filters, Slider loopsticks, and/or large

directional

external
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

SRF-T615,

Eton
E100 and C.Crane SWP stock Ultralights are very thrilling to take

along

on
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

kHz

AM
band tuning steps, and I'm sure that someone on the list can tell you
about
it (sorry, but my own manual seems to have disappeared, also). In the
early
days of the Ultralight boom (December 2007), the radio was one of the
most
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
probably
depends on the type of DX you pursue.

For domestic DXers looking for a little more sensitivity, the
modification
may help out somewhat. But for 9 kHz-split DXers chasing

transoceanic

DX

next

to strong domestic stations, these modest 450 kHz filters are not

going

to

provide any significant help. Both Steve and I enjoy this type of

transoceanic

DXing, which is probably why we are more demanding than domestic

DXers

in
evaluating filter performance.

We also have probably been spoiled by the phenomenal performance of

the

455

kHz Murata "K" filter upgrades in the Slider E100's, which routinely
allow
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

loop

antenna for more directivity. Ofcourse that throughs it in to the
ultralight
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

"keyboard

trick"?

ALEX N8UCN/KOH8IG






**************Worried about job security? Check out the 5 safest jobs

in a

recession.
(http://jobs.aol.com/gallery/growing-job-industries?ncid=emlcntuscare00000003)

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.


http://www.euroquartz.co.uk/pdf/ceramic-lts-450w.pdf


--- 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
huge
improvement and an excellent domestic DXing filter choice. It even
dabbles in split frequencies: at the beach this past Tuesday morning,
the
M37V was able to get good barefoot readability on 774-JOUB from Japan
when
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
are
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
will
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

one

of
the modest 450 kHz upgrades would place the radio in the "unlimited"
class.
Because of this, fanatical tinkerers do everything possible to boost
performance-- premium filters, Slider loopsticks, and/or large

directional

external
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

SRF-T615,

Eton
E100 and C.Crane SWP stock Ultralights are very thrilling to take

along

on
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

kHz

AM
band tuning steps, and I'm sure that someone on the list can tell you
about
it (sorry, but my own manual seems to have disappeared, also). In the
early
days of the Ultralight boom (December 2007), the radio was one of the
most
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
probably
depends on the type of DX you pursue.

For domestic DXers looking for a little more sensitivity, the
modification
may help out somewhat. But for 9 kHz-split DXers chasing

transoceanic

DX

next

to strong domestic stations, these modest 450 kHz filters are not

going

to

provide any significant help. Both Steve and I enjoy this type of

transoceanic

DXing, which is probably why we are more demanding than domestic

DXers

in
evaluating filter performance.

We also have probably been spoiled by the phenomenal performance of

the

455

kHz Murata "K" filter upgrades in the Slider E100's, which routinely
allow
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

loop

antenna for more directivity. Ofcourse that throughs it in to the
ultralight
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

"keyboard

trick"?

ALEX N8UCN/KOH8IG






**************Worried about job security? Check out the 5 safest jobs

in a

recession.
(http://jobs.aol.com/gallery/growing-job-industries?ncid=emlcntuscare00000003)