Sony M37W


Rick Robinson <w4dst@...>
 

Does anyone know what the "radio on a chip" IC Sony uses in the M37W? I have a broken one in addition to my new one and both the main ICs have had the ID obliterated. I know they are proprietary but some of Sony's proprietary chips do have data sheets that are available unlike the IC themselves.

I replaced both the FM and AM IF filters in my M37W with better muRatas and am very impressed with the results. It's interesting that they use a dual coil ferrite antenna for MW. As Allen in Newfoundland has shown, these are great little radios. If anyone is interested in replacing the MW filter, there is an ebay dealer in Poland that sells the 2.2kHz muRata filters for 450kHz IFs. I have dealt with him and highly recommend him.

Rick


Guy Atkins
 

Hi Rick,

Is the filter you are referring to from the 8dwa seller in Poland the Murata CFWLA450KJFA? (Old part #CFWS450IT?)

In the chart shown in his auctions, this is the narrowest 450 kHz filter available, but it is not 2.2 kHz, but +/- 2.0 kHz, for a total nominal bandwidth of 4.0 kHz.

Also, I see that the stop band attenuation--at only -50db instead of the usual -60db-- is a rather poor figure of 15 kHz total. Thus the shape factor is not very good.

An alternative filter to consider and which I'm currently using in a Sangean ATS-909X as a narrow position replacement is the CFWLA450KL6A002-B0 (what a mouthful!). This filter is 2.8 kHz and works very well as a narrow AM or SSB filter. For AM mode use, it helps to offset tune by 1 kHz for the best sound quality.

This 2.8 kHz, 450 I.F. filter goes by the ICOM part number of 2020001470. It's available for $10.07 each at ICOM America. It's used as a stock narrow filter in the ICOM PCR-1000, PCR-1500, and PCR-2500 receivers.

Last week I stopped by ICOM's parts department in Bellevue and they have some of these in stock.

73,

Guy Atkins
Puyallup, WA

--- In ultralightdx@..., Rick Robinson wrote:

I replaced both the FM and AM IF filters in my M37W with better muRatas
and am very impressed with the results. It's interesting that they use
a dual coil ferrite antenna for MW. As Allen in Newfoundland has shown,
these are great little radios. If anyone is interested in replacing the
MW filter, there is an ebay dealer in Poland that sells the 2.2kHz
muRata filters for 450kHz IFs. I have dealt with him and highly
recommend him.

Rick


Gary DeBock
 

Hi Rick,
 
Very early in the Ultralight radio boom (early 2008) the SRF-M37W's predecessor (the SRF-M37V) was already quite popular for DXing, and there was serious interest in improving its barn door wide selectivity. Hometown buddy Guy developed a 450 kHz IF filter mod at the time, which helped significantly. The problem was that there were no 450 kHz upgrade filters available with anywhere near the performance of the 455 kHz Murata CFJ455K5 IF filters, which could be installed in the 455 kHz IF Ultralights like the Eton E100 and C.Crane SWP Ultralight models. After Guy's CFJ455K5 IF filter mod was developed for the Eton E100 in June of 2008, this model became the state-of-the-art DX-chasing Ultralight for about a year.
 
73, Gary DeBock (in Puyallup, WA, USA)
 
 
   

-----Original Message-----
From: thinkdx
To: ultralightdx
Sent: Thu, Jan 17, 2013 10:12 am
Subject: [ultralightdx] Re: Sony M37W

 
Hi Rick,

Is the filter you are referring to from the 8dwa seller in Poland the Murata CFWLA450KJFA? (Old part #CFWS450IT?)

In the chart shown in his auctions, this is the narrowest 450 kHz filter available, but it is not 2.2 kHz, but +/- 2.0 kHz, for a total nominal bandwidth of 4.0 kHz.

Also, I see that the stop band attenuation--at only -50db instead of the usual -60db-- is a rather poor figure of 15 kHz total. Thus the shape factor is not very good.

An alternative filter to consider and which I'm currently using in a Sangean ATS-909X as a narrow position replacement is the CFWLA450KL6A002-B0 (what a mouthful!). This filter is 2.8 kHz and works very well as a narrow AM or SSB filter. For AM mode use, it helps to offset tune by 1 kHz for the best sound quality.

This 2.8 kHz, 450 I.F. filter goes by the ICOM part number of 2020001470. It's available for $10.07 each at ICOM America. It's used as a stock narrow filter in the ICOM PCR-1000, PCR-1500, and PCR-2500 receivers.

Last week I stopped by ICOM's parts department in Bellevue and they have some of these in stock.

73,

Guy Atkins
Puyallup, WA

--- In ultralightdx@..., Rick Robinson wrote:
>
> I replaced both the FM and AM IF filters in my M37W with better muRatas
> and am very impressed with the results. It's interesting that they use
> a dual coil ferrite antenna for MW. As Allen in Newfoundland has shown,
> these are great little radios. If anyone is interested in replacing the
> MW filter, there is an ebay dealer in Poland that sells the 2.2kHz
> muRata filters for 450kHz IFs. I have dealt with him and highly
> recommend him.
>
> Rick
>


Rick Robinson <w4dst@...>
 

Hi Gary and Guy,

Thanks for the info on the Icom filter, I'll order one and give it a try. The muRata is working fine for me and I can DX during the day on either side of local 1450 WHKP, and semi local WWNC, using this filter which was not possible with the stock filter. Installing a CFJ455K5 in a M37W would be impossible as it is very tight in there. I have a 455K5 in my trusty old FRG-7700 and it is a fine filter but way too big for the tiny Sony. It's a tight squeeze in an SWP.

Guy, is the muRata used in the Icom an SMD or pin device? I'm wondering about the small amount of space in the M37W.

Good DXing,

Rick


Guy Atkins
 

Rick,

The muRata filter used in the ICOM "PCR" radios is a pin type, and the form factor is a small black rectangle. These fit reasonably well on the M37V's (and presumably "W" model) PCB. You may need to extend a lead or two with small diameter wire to reach the appropriate through-hole on the board.


73,

Guy Atkins
Puyallup, WA

--- In ultralightdx@..., Rick Robinson wrote:

Hi Gary and Guy,

Thanks for the info on the Icom filter, I'll order one and give it a
try. The muRata is working fine for me and I can DX during the day on
either side of local 1450 WHKP, and semi local WWNC, using this filter
which was not possible with the stock filter. Installing a CFJ455K5 in a
M37W would be impossible as it is very tight in there. I have a 455K5
in my trusty old FRG-7700 and it is a fine filter but way too big for
the tiny Sony. It's a tight squeeze in an SWP.

Guy, is the muRata used in the Icom an SMD or pin device? I'm wondering
about the small amount of space in the M37W.

Good DXing,

Rick


Rick Robinson <w4dst@...>
 

Thanks Guy, the Icom muRata sounds like the same small black package as the 450IT that I used.  It barely fit inside the M37W.

Rick

On 1/18/2013 1:01 PM, thinkdx wrote:
 

Rick,

The muRata filter used in the ICOM "PCR" radios is a pin type, and the form factor is a small black rectangle. These fit reasonably well on the M37V's (and presumably "W" model) PCB. You may need to extend a lead or two with small diameter wire to reach the appropriate through-hole on the board.

73,

Guy Atkins
Puyallup, WA