SRF-M37V and SRF-M37W-Performance differences?
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msf1962 <www-clorofila-up-to@...>
Hi Kevin,
Re: SRF-M37V and SRF-M37W-Performance differences? Posted by: "satya@..." satya@... dhsatyadhana Mon Jan 26, 2009 6:58 am (PST) Hi Rob: While the M37V is not the worst selectivity-wise (the true "F" in this category is a Radio shack portable currently available, which is so bad it only tunes in about 8 different stations, one every 100 khz or so!), in stock form the M37V is tough to use in an urban environment. However, if you live outside of a strong RF environment, then it works very well, and Alan Willie in Newfoundland has set a lot of records with his stock unit. I have an M37V with the filter replaced which transforms it into a new radio, but if you are not up for that kind of technical task, then the M37V/W may not be for you. Kevin S Bainbridge Island, WA |
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msf1962 <www-clorofila-up-to@...>
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 Re: SRF-M37V and SRF-M37W-Performance differences? Posted by: "satya@..." satya@... dhsatyadhana Mon Jan 26, 2009 6:58 am (PST) Hi Rob: While the M37V is not the worst selectivity-wise (the true "F" in this category is a Radio shack portable currently available, which is so bad it only tunes in about 8 different stations, one every 100 khz or so!), in stock form the M37V is tough to use in an urban environment. However, if you live outside of a strong RF environment, then it works very well, and Alan Willie in Newfoundland has set a lot of records with his stock unit. I have an M37V with the filter replaced which transforms it into a new radio, but if you are not up for that kind of technical task, then the M37V/W may not be for you. Kevin S Bainbridge Island, WA |
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satya@...
Hi Milton:
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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 ! |
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Gil Stacy
Kevin,
I'll send photos of the change out to Milton.
Gil |
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Hello Guys,
I agree 100% with Steve about the rather disappointing performance of those
450 kHz filters.
During the winter, Steve and I both invested significant time and effort in
a project to modify the Sangean DT-400W and DT-200VX models for both increased
sensitivity and selectivity. Steve did a great job even finding the space to
install those filters, inside the cramped DT-400W cabinet.
Although the Slider loopstick modification worked as well as the E100
equivalent, the selectivity boost provided by the 450 kHz filters (mentioned in
the DXer.Ca article) was almost negligible. Small 450 kHz IF filter upgrades are
nowhere near as effective as the premium 455 kHz filter upgrades (like the
Murata CFJ455K5, used in the fully modified Slider E100's and Slider SWP's). The
DT-200VX and DT-400W modification projects were abandoned for this reason, in
favor of experimentation on the C.Crane SWP (455 kHz IF) model.
73, Gary
In a message dated 4/2/2009 9:10:55 A.M. Pacific Daylight Time,
steveratz@... writes:
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satya@...
Thanks, Gil! Can you copy me as well? I am thinking about getting the
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narrower version of the filter, and would like to provide it to my friend who has agreed to do the work. Thanks! Kevin Kevin, |
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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
.
In a message dated 4/2/2009 11:22:18 A.M. Pacific Daylight Time,
rifleman336@... writes:
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--- In ultralightdx@..., satya@... wrote:
Can you make that three copies for I'm intrested in the mod also. Unless I can find out who kevins using for the mod. Also the ceramic filters, What would be the best source for them? ALEX N8UCN/KOH8IG |
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satya@...
Hi Alex/all:
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This line of filters: http://www.velco-electronic.com/pdf/quartz_crystal/Ceramic%20Filters%20LT450-455.pdf is generally available from eBay seller "anonalouise" - see for example eBay item #9730959591. The model number I have in my unit is the LTS-450-GW. The eBay seller has the LT version, which per the Velco Electronic pdf above is virtually the same (pins 0.5 mm longer, case 0.5 mm wider), so I am assuming it would be compatible? Kevin S Bainbridge Island, WA --- In ultralightdx@..., satya@... wrote: |
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Steve Ratzlaff <steveratz@...>
I bought some of those filters from the same Mainline UK seller, to try in the DT400 ULR per the enthusiastic filter mod article on the dxer.ca site. It was very hard to do the mod, and the results were definitely not worth all the effort. Gary DeBock also tried the radio in his high-RF environment.
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These are very small filters and can't offer good skirt selectivity. There's no getting around the fact that it takes physical size to make a good filter. I would be skeptical that much improvement would be noted in the M37V ULR with such a filter mod. But at least you aren't out much money for the cost of the filter, if you want to try the mod. Steve ----- Original Message -----
From: <satya@...> To: <ultralightdx@...> Sent: Thursday, April 02, 2009 8:52 AM Subject: Re: [ultralightdx] Re: SRF-M37V and SRF-M37W-Performance differences? Hi Alex/all: |
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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:
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Hello Guys, So in the end it's a useless exercise?? Too bad it would be nice to find some improvment for it. Alex N8UCN/KOH8IG ALEX N8UCN/KOH8IG |
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--- In ultralightdx@..., D1028Gary@... wrote:
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 |
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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:
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satya@...
Hi Alex/All:
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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, |
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Michael Slattery
Whether the 450 kHz filter modification would be useless or not probablyBefore 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'. Amongst others I live within 15 miles 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(s) are not really that challenging? Maybe that is the reason you are not reaping the reward from the mod? -- Michael Slattery Sheffield, UK -- Michael Slattery Sheffield, UK |
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--- In ultralightdx@..., D1028Gary@... wrote:
Double bummer!!!!:>( :>( Not only did you rain on my parade, but now you had to drop a wall cloud over it to!!! :>0 :>) Oh well, I can always dream. Well it looks like I'm in the market for acquiring yet another SRF M37V/W to convert in to an M37X??!!! Sort of the way I'm looking for more SRF-39/49/59 to mod up in to a "retro" expedition reciever. Alex N8UCN/KOH8IG |
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Chris Knight <chris@...>
Just a silly question. How hard would it be
to change the I.F. of one of these small radios from 450kHz to 455kHz? Could it
be as simple as changing a mixer IC or a crystal?
73,
Chris Knight
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msf1962 <www-clorofila-up-to@...>
Hi Kevin & Gil !
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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 i´ve a simple question : I´m eying the Velco Electonic table with all the filters and i don´t 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-GW´s 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 > |
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Steve Ratzlaff <steveratz@...>
Hi Milton,
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Unfortunately the UK eBay seller doesn't carry the ITW filter or any of the other narrower filters--I would like to obtain those narrower filters too. If you can obtain the ITW filter, you can certainly install it and it would work better than the wider GW filter for DX purposes. 73, Steve ----- Original Message -----
From: "msf1962" <www-clorofila-up-to@...> To: <ultralightdx@...> Sent: Friday, April 03, 2009 4:47 PM Subject: [ultralightdx] Re: SRF-M37V and SRF-M37W-Performance differences? 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 |
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