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Need help in 88-108MHz preamp circuit!!

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by rahulan999, Aug 25, 2008.

  1. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    I think he's confused?, 455KHz is the standard AM IF frequency, or the second IF in a narrowband FM receiver - standard FM is 150KHz width.
     
  2. radiomate

    radiomate New Member

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    Broadcast FM stations are spaced at 200KHZ, as I recall. I am using 150KHZ filters in my FM receivers at the expense of slightly reduced audio fidelity.
     
  3. Hero999

    Hero999 Banned

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    200kHz spacing makes sense even if each channel is only 150kHz wide because there needs to be some leeway to prevent crosstalk.
     
  4. dave

    Dave New Member

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  5. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Not at all, you are using the correct filters - the 200KHz is the spacing BETWEEN channels, not the bandwidth - it's also different in the USA and Europe. The 150KHz is also for stereo channels, you can use a smaller bandwidth for mono only stations (if any exist these days?), some older high quality tuners were switchable accordingly - my oldish Kenwood tuner is (or was, as it's packed away unused now).
     
  6. rahulan999

    rahulan999 New Member

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    Got mistake! I was talking about the SFE10.7MS2-A specified on the IC datasheet. But again, it's not 455KHz it's a 230KHz BW type recommended by Philips.

    You are right. My filters are 50KHz BW when searched on net and seems to be useless for the project.

    I have got a different set of piece which marked as L10.7A and not from muRata. This link,
    The FM Ceramic Filter Page says that it's a 280KHz BW type.

    I am pretty sure that I can use it without any compromise on audio quality but a slight reduction in selectivity which I dont mind as long as I'm not able to find a 180-230KHz BW filter as I have given primary preference for the audio quality.
     
  7. rahulan999

    rahulan999 New Member

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    Here classical music,news and health services are operated on mono mode, apart from seven(almost are private) stereo music transmissions ;)
     
  8. radiomate

    radiomate New Member

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    Hey guys did you see my 9 tube-3 IC homemade stereo FM receiver? It has a tuned RF amplifier, a ratio detector and 5 double-tuned IFTs for very good selectivity. The receiver (tube) and decoder/amplifier (solid-state) have independent power supplies. It is beautifull to use in the dark :) Read all about it here:

    http://www.midcenturyradios.com/HM-9TuberFM.html
     
    Last edited: Oct 17, 2008
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    We can buy a very expensive vacuum tubes amplifier. Its tubes glow in the dark and it heats your home but the tubes are not part of the solid state amplifier circuit. They are there only to be seen and make some warmth.
     
  10. rahulan999

    rahulan999 New Member

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    Wow!! mind-blowing..

    I'm ready to buy it...so that I can help u to keep ur house cool :D
     
  11. radiomate

    radiomate New Member

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    Na, I'd rather keep it to keep my house warm in winter, unless you can spare $5,000 for a homemade heater, then you can have it ;)
     
    Last edited: Oct 17, 2008
  12. rahulan999

    rahulan999 New Member

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    My God..after a long long years, i came to memorize my ugly 4th standard teacher who taught me that '0's are having no values unless otherwise standing with others :rolleyes:
     
  13. rahulan999

    rahulan999 New Member

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    Sometimes I wonder on the extreme construction techniques followed by old radios. All the spares were of high quality and clever assembly! After IC's came radios are made by local industries also and quality became pathetic. Older ones are gold and they run for many years even after rough uses. Nowadays, I think it's not possible to achieve such quality.
     

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  14. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You get what you pay for - but old valve radios certainly weren't reliable, transistor ones were far more so - the quality of components used in valve radios wasn't high either, poor quality resistors, poor quality capacitors, electrolytics failing, wavechange switches failing - they were full of poor parts and failed all the time.

    You're looking looking back through 'rose tinted glasses' - decent quality modern gear is far more reliable than the old gear was (the cheap junk from China isn't, but it's not going to be).
     
  15. rahulan999

    rahulan999 New Member

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    But they have tried on their best to achieve maximum quality possible at that time. Only dedicated brands were on play! Nowadays, even though the technology developed it's difficult to differentiate good and fake parts available everywhere.
    I agree that most reliable products can be purchased now on good pay, especially branded world-band receivers are of high quality types.
    But I have seen receiver IC's and output IC's are sometimes failing even in a branded moderate type receivers also.
    Transistor receivers made on 70's-80's were worked for long duration and quality of assembly were very good.
    Whenever I see a valve based assembly, I think about my fused incandescent lamps in my home :D
     
  16. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Grundig (German company) made many excellent world-band radios until they went bankrupt in 2003. The new Grundig company sells junk.
     
  17. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Well it's not a new Grundig 'Company', just a name now 100% owned by the Turkish company Beko, they use the Grundig name as a badge on cheap crap.

    Where I work we used to be a major Grundig dealer, and we took ALL the stock when they closed the Irish branch - it was all loaded in containers to go back to Germany, and we bought the lot - at VERY, VERY good prices.

    There were loads of Grundig Tuner/Amplifiers - model R45 - 45W RMS per channel, FM presets, and the tuner of the usual Grundig quality. They sold for about £500 - we sold them for £99 :D
     
  18. rahulan999

    rahulan999 New Member

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    Well guys, I have collected 5 set of 'Philies' IFTs :D when I searched for Philips original parts that exactly on the way of above quoted comments!

    After I returned back home only I understood I was fooled:mad: but along with it I got original Philips RF coils(red core) made in 1990 as service part.

    IFT itself is quite difficult to find, gone obsolete and I think the 5 sets are valuable for me. They are marked as for use with IC's.

    Same time I'm trying for a PCB design and etching for the project.

    Soooooo...the troubles are almost over and I'm quite confident to start with a TEA5711 radio broadcast receiver that can be expected after a couple of months. Thanks very much for everyone who have accompanied me through this thread and made me more knowledgeable for the project ;)
     

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