dinsdag 2 juli 2013

Sony XDR-F1HD as wideband receiver

Introduction;


The Sony XDR-F1HD FM tuner is wellknown.
Especially its IF properties are excellent.  Tuning however doesn't go pretty fast and the coverage is, off course, only 88 till 108 Mhz. The idea came to create a wideband receiver with a convertor.
But didn't want to grab in the Sony's innerpart.
The solution wasn't that hard. I built a simple convertor which is able to convert the 2nd IF (58.075 Mhz) of a Uniden  9000-XLT radio to 106.1 Mhz. This fine receiver covers 25 till 1300 Mhz .
By mixing it with 48.025 Mhz the output becomes 106.1 Mhz.

The choice for 106.1 Mhz was only because there isn' t a strong station working around that frequency at my QTH that might harm the reception. Besides I found a 16.000 Mhz crystal in store. In third overtone appeared it 48.025 Mhz so a good choice.
When built in a metal box even the second harmonic of the X-tal on 96.050 mhz doesn't harm.

So one can in fact choose the output frequency . The only requirement is that the crystal oscillating frequency has to end with 25 Khz. For example 29.425 Mhz will give: 87.500 output and so on.
Other receivers may be converted the same way.

Realisation : 

On the backside of the Uniden I made a BNC plug and tapped the IF of 58.075 Mhz via a 1 pf capacitor.
I already owned an old convertor with the NE602 that was designed to convert 30-50 Mhz into 88-108. So only had to change the X-tal and output coil.

The circuit


Results: 


It works very well. The UBC-9000 XLT has a convenient tuning dial. The steps can be choosen: 5, 12,5 , 25 and 50 Khz. Tuning goes very quickly compared with the F1HD.
When comparing sensitivity on the FM band, there appeared no difference with the Sony .
When a neighbouring channel is a strong it helps to tune just next to the frequency.
For example Tacolneston on 91.9 Mhz could be improved that way.
On 53.75, 56.25 and 60.75 Mhz the reception of television sound channels became better.










In fact you can omit the RF stage. The IF output is already strong enough.

This attenuator I use to regulate the output level of the convertor to the best value.

















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