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Old 13th September 2005, 10:56 PM   #1
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Default Build a SUPRX tuner?

I only have crappy tuners(Except in my hk670), but instead of spending a lot of $$$ on a commercial one, I'd like to build a good one.

Do you think this one would be pretty easy to build?
http://rfdesign.com/mag/radio_highpe...ver/index.html

I see some impossible to find components. Is it still worth trying to build one?
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Old 14th September 2005, 12:04 AM   #2
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Unless you're very experienced with RF desing, including PCB RF desing, it would be a difficult job. It will also probably be more costly than to buy a comparable used tuner on ebay. Specific RF parts can also be difficult to source in small quantity.

A good circuit can have marginal specs once mounted on a PCB, if the PCB is not designed correctly.

To build and desing a tuner you need RF test equipments. I have maybe 100K worth of RF test gears and you would need most of that. RF FM generator, Modulatio meter, RF voltmeter, FET active probe, High frequency frequency counter and maybe a spectrum analyser for Front end and IF testing.

An finally the big questions:

Most, if not all commercial stations (exception CBC here in Canada) have very loosy sound to start with. They are very compressed and most of them use mp3 play list by now with lossy compressed mp3 files. So not much quality to listen too.

Future of radio seems to be digital, so to invest a lot of money in analog tuner seems to be risky. Myself I have one good NAD Reference serie tuner and all my other tuners are Denon, Panasonic, Technics and the like. The cheap ones were given to me ;-)

Just my two cents. And by the way I worked and designed RF equipement for almost 20 years now.

Bye...
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Old 14th September 2005, 12:51 AM   #3
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So commercial is the way to go?(Even these are not properly adjusted anyways)

Quote:
Most, if not all commercial stations (exception CBC here in Canada) have very loosy sound to start with. They are very compressed and most of them use mp3 play list by now with lossy compressed mp3 files. So not much quality to listen too.
Oh, that's why we hear MP3 artefacts on highly commercial stations. At least, the only station I listen to is chom(classic rock), and they use mostly LPs as source(I think). There are no MP3 artefacts on this channel, and I can't hear compression anywhere, not even in advertising. Only once, there was a tune that was highly compressed but I guess it's part of the source they have.

I think they use LPs because LP albums are still available, sometimes there's some LP popping and one of their program is either side 1 or 2 of an album & as far as I know, there's only 1 side to CDs.

btw, CBC is not commercial. Have you already heard commercial advertising on CBC? Me, no. At least not on CBF-FM.
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Old 14th September 2005, 02:47 AM   #4
BrianL is offline BrianL  United States
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I'd strongly suggest buying a used "classic" tuner from
the late 70's and early/mid 80's. Kenwood, Sansui,
Technics, and others come to mind. There are any number
that can be had on eBay and elsewhere for reasonable prices
that would do just fine with a few standard audiophile mods
and a good alignmnet. Better than anything you can buy
today for a reasonable price. I'd suggest reading the
info at www.fmtunerinfo.com for the low-down. The only
caveat I have is that they tend to be a bit biased to
DX'ing (long distance reception). So if you live in a
large city with crowded band or in the middle of nowhere
where you can't even think about getting the next town
over, you need to take some of their comments with a
grain of salt. But overall very good info.
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Old 14th September 2005, 03:11 AM   #5
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I love my Sansui TU-717 (just had to get that out!)
It sounds really good,and can pull in signals pretty well.
I just built a J-pole antenna,and connected it.. WOW! I can hear stations from all over now!
Next I might do a couple tweaks to it- replace some caps,etc and maybe try a IF filter mod,and do some DX'ing!
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Old 14th September 2005, 11:51 AM   #6
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Quote:
I'd strongly suggest buying a used "classic" tuner from
Oh that's why the hk670 sounds so good. It has something I never saw: 54dB stereo separation.
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Old 14th September 2005, 02:29 PM   #7
forr is offline forr  France
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I love FM listening and find it's a pity that FM DIY projects have all disappeared. Some were not too difficult to build and true, there are very good second hand stuff.
My own experience with a Linsley-Hood project, built from a Hart kit (England) turns to an audio failure. The stereo separation is very very poor. Since fifteen yeas, I spent hours to make it ok, without success.
Claimed specs were impeccable !

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Old 14th September 2005, 03:15 PM   #8
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Quote:
My own experience with a Linsley-Hood project, built from a Hart kit (England) turns to an audio failure. The stereo separation is very very poor. Since fifteen yeas, I spent hours to make it ok, without success.
I've been told stereo works better with discriminators, and that it is very poor when using ratio detectors.

Quote:
I love FM listening and find it's a pity that FM DIY projects have all disappeared. Some were not too difficult to build and true, there are very good second hand stuff.
Someone gave me an EICO HFT-90. It sounds a bit better than standard tuners, but it's mono. It originally was a kit tho.


The only thing is that old tuners on ebay often cost pretty much money.
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Old 14th September 2005, 08:22 PM   #9
AuroraB is offline AuroraB  Norway
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I more or less totally agree with Algar.......both on the technical aspects and the general programme quality.....

Last bit first...every now and then a program pops up using LPs, probably because the music is fairly uncommon to the broader public, and thus not yet reissued on CDs....
most of the programme material is hopelessly destroyed by using MP3s and multiband compressors.

On the technical aspects, you will probably have severe problems sourcing things like top quality filters and IF coils and transformers in small quantites, - and you will need a fair amount of RF test eq. to set it up properly.
It is true that the possibly best FM detector is the double slope detector, buth this need s very careful tuning, - and rertuning, as it will drift over time. The comment on modern tuners not being properly trimmmed or tuned, is mostly true, as they are designed specifically for requiring minimum or no tuning at all! Manual labour means cost-- simple as that!


If you want a good tuner - find one of the classics at Ebay---the ones with manual tuning, - something like a Kenwood, Sansui,Rotel or better- a Luxman......then find an old geeser of a technician, who knows what he is doing, and have him retune the thing,- and you are all set. Even if it might still be pricey, - 2-300 bucks (?), you will be spending at least thaht much on parts, if you were able to find them.

Good luck --from another almost old geeser of an engineer

BTW-- Sequerras and Rohde & Schwartz used to be the Rolls Royce of programme monitoring....
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Old 14th September 2005, 08:38 PM   #10
forr is offline forr  France
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In France we are very lucky with programs : I think France Musique is a real reference of what can be done with FM, particurlarly in direct broadcasting. There are at least six other stations whose sound is really first class wiht absolutley no audible compression.

I own a Leak FM mono tuner (wiht no component ever changed, a This tuner is rated as the best ever made by HiFi World (England). I only compared its mono sound to other recent stereo tuners. Till now, I think HiFi World may be right.

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