The Sony SRF-59
SWLing Post reader, Steve, writes:
I check in on your blog frequently. I’ve been a casual SW and AM dxer since my childhood. I’m a mechanical engineer, and have some basic electronics knowledge, but I’m no RF expert, and half forgot most of what I used to know.
On 9-13-15, around 11am eastern time, I was playing with a Sony SRF-59 down low on the AM band. The lowest station I can hear at my location near Valley Forge PA is a Spanish language station on 540–WLIE, on Long Island I think. My dial is badly calibrated but I know I was below that station on 540, maybe even below 530 or 520, and heard some noise. It took some really careful back and forth tuning, but I could hear a voice. I put the radio against my AN200 passive loop and heard the clear unmistakable voice of “Brother Scare”, (Overcomer Ministry). I scanned the shortwave and found a simulcast on 9840, WHRI Cypress Creek SC. The info I have says it’s a 250 kW broadcast.
Grundig AN200 Loop Antenna
I scratched my head and thought there must be a pirate rebroadcasting it on the bottom of the AM band, but I couldn’t hear it on my CC 2E, or my Grundig G3 which tunes continuously from LW into MW. It is really touchy to tune on the SRF-59, but with work, I could hear him barefoot, and very cleanly with the loop. I checked in several times the next few hours and it was there until WHRI went off the air at 3pm I think. Unfortunately, I never got a station ID.
On the morning of Monday Sept 14, at 9pm local time, with the same radio and loop, I got a station ID for China Radio International, and then found the same broadcast on 9570 from Quivican Cuba–also a 250 kW signal. I could not hear it clearly barefoot, as with WHRI, (it is quite a bit more distant) but with the loop is was incredibly clear. Also it doesn’t seem to matter where the tuning dial on the loop is, or how it’s oriented (I was aimed east/west). The radio and loop both function normally higher up the AM band (you need to tune the loop, and the reception is amazing with it).
I know I was below 540, because I passed local stations on the way down–610(WIP), and 560 (WFIL)–and could hear Spanish voice just below that, which had to be 540. The shortwave was just below that. The only thing i get below that on any other AM radio is Cuba and Canada on 530, both of which I can obviously only get at night time. I don’t know how the tuning circuits could jump 9mHz so suddenly.
Call me mystified. I thought I could find something about this on the net; I can’t be the only one with this experience; but no. Have you ever heard of this?
Steve followed up later noting that he is actually able to tune in the whole 31 meter band, as long as a signal is strong enough to overload the SRF-59.
I’ve done a lot of MW DXing with the SRF-59 and had never noticed harmonics, but I’m not surprised they can be heard either. I might try to replicate what Steve did using my AN200 loop coupled to the SRF-59.
Has anyone else as heard 31 meter band signals on their SRF-59?
I had an SRF-39FP while in prison in Mississippi and I was able to pick up SW broadcasts from all over the place (I mainly listened to Radio Havana, both english and spanish broadcasts) and could pick up the time signal from the atomic clock in colorado. It involved shorting out a connection on the board and clipping one of the AM antenna wires and adding a long length of wire to the clipped wire. I ended up scrapping 4 sets of earbuds and splicing the wires end to end but it worked great.
I do it with my SRF-S84, during the day you touch a heater of the central heating, or any large metal barrier, you can catch a dozen shortwave stations. It has the same chip as the SRF-59, doesn’t it?
20 years ago I did it with my S80 and it was totally crowded with SW stations.
It’s very hard to adjust the frequency, but when it’s done, the sound is very clear, comparable to a cheap SW radio.
HF feedthru is more usual on SRF-59’s than on 39’s,
probably due to lack of care in tuning them at
the factory and so forth.
You might wish to do a tuneup of the AM section,
it might correct this or minimize it.
But if you live near an HF broadcaster (like EWTN here)
it’s a bit academic.
I too have heard this, always on the Cubans and occasionally on the Nashville stations. Probably overload and or mixer products. There is a SW mod for this radio on the net.