Re: Sony SRF-18



to know the chip was the main reason for opening the receiver.
Unfortunately I still don't know it definitly.

The chip is placed on the underside of the PC board. To read the
inscription I'd have to remove it, what is mechanically too complex
and risky for me.
Most parts are named on the board itself. Above the chip I read
"SRX 7709M6". So it is possible but not shure, that there is a
chip SRX7709M6 in it.

Anyway,after many hours of listening I must say, that the chip used in the SRF-18 stands up to the famous CXA1129N, if it isn't it.

If I find a very cheap SRF-18 I'll destruct it completely to know better, but the interest to do that is no longer the same, since I
know that the SFR-18 is not an Ultralight.

Perhaps somebody of the group knows better.


--- In ultralightdx@..., "mediumwavedx" <mediumwavedx@...> wrote:


What receiver chip is used?


--- In ultralightdx@..., "slowfly55" <peter.keller@> wrote:

Hello Gary

I am very grateful for your clear reply. I understand, that the
definition "approximately 20 cubic inches" is strictly interpreted,
holding tight to the original Ultralight concept, a thing I fully
BTW, opening the SRF-18 I realized, that the antenna is only about
3" long, about half the length of the case.The sensitivity gain
is the more astounding.
Thinking of any modifications is however beyond interest, if it is
not an Ultralight.

Thanks, Peter

PS: The ebay listing gives the max.dimensions you'd need if putting
the radio into a box. As 2 of the dimensions are variable, i.e. smaller toward the outside, the real volume is about 21 to max.22 cub. inches,in any way still clear above 20. So independent of
the method of measuring your verdict remains valuable.

--- In ultralightdx@..., D1028Gary@ wrote:

Hello Snowfly55,

The Sony SR-18 is a dual-speaker portable with dimensions at 6 1/8" x 3 1/8" x 1 3/16" ("not including projected parts," according to the current eBay listing posted at ). As such, its volume works out to about 24.4 cubic inches, or well above the Ultralight radio qualification limit of 20 cubic inches.

Dual-speaker portables like the Sony SRF-18 and Tecsun PL-398 typically have longer loopstick antennas than qualified Ultralight radios, which give them an extra advantage in AM sensitivity. Of course, you are welcome to use any portable radio that you wish for DXing, and even report the results here on the list (which certain DXers have already done, for the Tecsun PL-398 dual-speaker model). But for Ultralight Radio classification (and Ultralight Awards qualification), we must follow the established guidelines, in order to maintain our unique identity in the AM-DXing community.

73, Gary DeBock (in Puyallup, WA, USA)
Ultralight Radio Group Co-Founder

-----Original Message-----
From: slowfly55 <peter.keller@>
To: ultralightdx <ultralightdx@...>
Sent: Thu, Apr 11, 2013 8:33 am
Subject: [ultralightdx] Sony SRF-18

For some years there hasn't been an Ultralight review with the
newest receivers. Some contributions to the list let me doubt if the
original definitions are still strictly adhered.
I like the Sony SRF-18 very much for its barefoot sensitivity, that is among the best. Measuring the radio is not quite easy due to its
curved outlines. I guess it is slightly above 20 cubic inches. Can
it still be considered as an Ultralight?

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