Hi forr
Thanks for the correction. I don't know what i do to the url addresses and they don't work. It is the third time I screw it up. ( had a few times i did it properly though)
At the said address, the comments for these tuners were very positive. I don't know what part of it is due to the specific topology, pulse count that is.
Regards
George
Thanks for the correction. I don't know what i do to the url addresses and they don't work. It is the third time I screw it up. ( had a few times i did it properly though)
At the said address, the comments for these tuners were very positive. I don't know what part of it is due to the specific topology, pulse count that is.
Regards
George
Tuner kit
Hi all
There are a few weeks now that I have received some FM Tuner kits (Larsholt LH7254) from Mr. Kiralyvalvy (“Kilary” see post#5). This is a superheterodyne receiver in a single sided pre-assembled PCB. Basic kit components are: TDA1062 front end IC, two broadband (250KHZ) IF ceramic filters, CA3189 IF IC (with a single discriminator coil), CA 741 for the AFC drive, CA 1310 stereo decoder IC.
A 100Kohm tuning potentiometer, 2 10Kohm trimmers, 2 resistors, 2 output cups, and a 12V DC PSU is what is required for a dry start.
Signal strength meter, Centre-Tuning meter, Stereo LED, Stereo/Mono switch, AFC On-Off switch, Mute On-Off switch (mute level adjustment is on board) can be directly wired to the appropriate output points of the PCB. (I tried them, they work OK). There is a buffered output for a frequency counter as well.
Kit arrived pre-adjusted with components for stabilized PSU, LED, RCA outlets and a few electrolytics generously supplied as a bonus.
For start, I tried it with a 12V 7.2 Ah lead battery.. With this loose implementation (80cm single wire for antenna, flying long leads), it works fine. 92mA consumption with LED and the two meters connected, 80 mA without. Around 600mV RMS AF output , superimposed on 800mV DC. Output cups required! It is stable, no drift even with AFC off.
In mono, very silent. In stereo there is a hiss (Scope trace shows 38KHZ remains and on strong modulation 57 KHZ as well). Compared in mono to a Tivoli, sound is more clean and detailed. Compared to a Kenwood KT-660L in mono and stereo, highs are clean, very good lows, detailed mids.
As is (I am in the process of doing some minor mods), the kit sounds very good. Easy to make it work and at a fare price as well. For a descent user-friendly tuner though, a 10 turns 100Kohm tuning potentiometer and a frequency indicator are required. I have ordered a Bourns potentiometer and I am in search for a cost effective way for implementing an appropriate frequency counter. Any help on this will be greatly appreciated.
Regards
George
Hi all
There are a few weeks now that I have received some FM Tuner kits (Larsholt LH7254) from Mr. Kiralyvalvy (“Kilary” see post#5). This is a superheterodyne receiver in a single sided pre-assembled PCB. Basic kit components are: TDA1062 front end IC, two broadband (250KHZ) IF ceramic filters, CA3189 IF IC (with a single discriminator coil), CA 741 for the AFC drive, CA 1310 stereo decoder IC.
A 100Kohm tuning potentiometer, 2 10Kohm trimmers, 2 resistors, 2 output cups, and a 12V DC PSU is what is required for a dry start.
Signal strength meter, Centre-Tuning meter, Stereo LED, Stereo/Mono switch, AFC On-Off switch, Mute On-Off switch (mute level adjustment is on board) can be directly wired to the appropriate output points of the PCB. (I tried them, they work OK). There is a buffered output for a frequency counter as well.
Kit arrived pre-adjusted with components for stabilized PSU, LED, RCA outlets and a few electrolytics generously supplied as a bonus.
For start, I tried it with a 12V 7.2 Ah lead battery.. With this loose implementation (80cm single wire for antenna, flying long leads), it works fine. 92mA consumption with LED and the two meters connected, 80 mA without. Around 600mV RMS AF output , superimposed on 800mV DC. Output cups required! It is stable, no drift even with AFC off.
In mono, very silent. In stereo there is a hiss (Scope trace shows 38KHZ remains and on strong modulation 57 KHZ as well). Compared in mono to a Tivoli, sound is more clean and detailed. Compared to a Kenwood KT-660L in mono and stereo, highs are clean, very good lows, detailed mids.
As is (I am in the process of doing some minor mods), the kit sounds very good. Easy to make it work and at a fare price as well. For a descent user-friendly tuner though, a 10 turns 100Kohm tuning potentiometer and a frequency indicator are required. I have ordered a Bourns potentiometer and I am in search for a cost effective way for implementing an appropriate frequency counter. Any help on this will be greatly appreciated.
Regards
George
Hi Gpapag,
For modifications, it would be interesting to investigate for stereo decoders. I own TCA4500A board made by Velleman (ref 2553) and the Linsley-Hood sample and hold decoder. I currently can't make any comment, having not seriously installed them. I hope to do it soon.
I would be reticent about a digital frequency counter, fearing entrance of parasitic pulses in the tuner. Linsley-Hood published one a long time ago.
I have schematics for all of that, if you are interested, send me an email.
For modifications, it would be interesting to investigate for stereo decoders. I own TCA4500A board made by Velleman (ref 2553) and the Linsley-Hood sample and hold decoder. I currently can't make any comment, having not seriously installed them. I hope to do it soon.
I would be reticent about a digital frequency counter, fearing entrance of parasitic pulses in the tuner. Linsley-Hood published one a long time ago.
I have schematics for all of that, if you are interested, send me an email.
Hi forr
Thank you for the help regarding frequency counter schematics. I appreciate. (you have blocked your e-mail from the forum. So, please e-mail me your e-mail address).
I have the same concerns for possible pulse-induced interference. Can you suggest any other means for having frequency indication using a 10-turns tuning potentiometer?
Regards
George
Thank you for the help regarding frequency counter schematics. I appreciate. (you have blocked your e-mail from the forum. So, please e-mail me your e-mail address).
I have the same concerns for possible pulse-induced interference. Can you suggest any other means for having frequency indication using a 10-turns tuning potentiometer?
Regards
George
I looked up those ICs at http://www.datasheetarchive.com/ . They are 30 year old circuits, so surely there must be newer ICs. Maybe Tamas has a newer design uning modern ICs.
Regards,
Ray
Regards,
Ray
Hi Gpapag,
Allow me a few days to scan the Linsley-Hood's article, it is very old, it is just for inspiration.
I modify my options so my e-mail should now be available. Some tuners have used simple coil meters as frequency indicators, the little difficulty lies in the writing of the frequencies scale.
Allow me a few days to scan the Linsley-Hood's article, it is very old, it is just for inspiration.
I modify my options so my e-mail should now be available. Some tuners have used simple coil meters as frequency indicators, the little difficulty lies in the writing of the frequencies scale.
Hi Ray
Yes, Mr Kiralyfalvy has another kit with discrete FETs at the front stage and the 4500 as the stereo decoder. I may try it also. As for the TDA1062, he wrote me that he still prefers this IC due to it's good performance. CA3189 is a classic, proven design. The CA1310 is the one that shows it's age.
Forr
If i will be left with no other option (freq. meter), i will do it with the pulleys, strings and the needle. But i really prefer the direct precise freq. indication of a digital counter
Regards
George
Yes, Mr Kiralyfalvy has another kit with discrete FETs at the front stage and the 4500 as the stereo decoder. I may try it also. As for the TDA1062, he wrote me that he still prefers this IC due to it's good performance. CA3189 is a classic, proven design. The CA1310 is the one that shows it's age.
Forr
If i will be left with no other option (freq. meter), i will do it with the pulleys, strings and the needle. But i really prefer the direct precise freq. indication of a digital counter
Regards
George
Hallo fellow DIYers,
Recently I have built a stereo FM tuner. An article about this project with literature references and schematics is posted on my website. The correct link is:
http://home.hetnet.nl/~a.van.waarde/id21.htm
The design dates from 1974 but all parts can still be purchased (in Holland, with exception of the Valvo FD-1A). Note that this is a cheap and simple tuner which can be easily reproduced, yet it performs reasonably well.
Greetings,
ArensAttic
Recently I have built a stereo FM tuner. An article about this project with literature references and schematics is posted on my website. The correct link is:
http://home.hetnet.nl/~a.van.waarde/id21.htm
The design dates from 1974 but all parts can still be purchased (in Holland, with exception of the Valvo FD-1A). Note that this is a cheap and simple tuner which can be easily reproduced, yet it performs reasonably well.
Greetings,
ArensAttic
ArensAttic,
That circuit would have rather modest performance. You can show analytically that 6 tuned circuits are required in the IF for adequate alternate channel rejection and 4 tuned circuits are required in the RF amplifier for adequate image rejection. With ceramic IF filters so inexpensive there is no reason now for inadequate IF filtering. I don't know of any simple inexpensive solution for the RF filtering.
Regards,
Ray
That circuit would have rather modest performance. You can show analytically that 6 tuned circuits are required in the IF for adequate alternate channel rejection and 4 tuned circuits are required in the RF amplifier for adequate image rejection. With ceramic IF filters so inexpensive there is no reason now for inadequate IF filtering. I don't know of any simple inexpensive solution for the RF filtering.
Regards,
Ray
offset reading frequency counters
Hi all,
You guys put me back about 25 years.
There are/were chips avalable that did an automatic offset correction with the right jumpers set.
Years ago I worked for Mr Kahn of AM Stereo Fame, and some of our early conversion radios (pre PLL days) were of the LO being a standard tuner and a frequency counter chip. You could select standard offsets to be applyed to the reading.
So if your radio was a high side injector, a normal counter chip would see 118.4 mhz. The chip would subtract 10.7 and display 107.7.
The same deal if it was a 'low side' injector radio.
You still see these counters avalable today on some CB radios. In transmit they read 'direct' and in receive the display the LO +/- some value.
Some 'comercial' tuners still use the VFO style receivers and have digital readouts. Might pay to get a peak at the service manual and copy a design that works. Then again some car radios are so cheap that for 25 bucks, you can take the parts you want and scrap the rest.
Ive also got a vauge memmory of just such a circuit being avalable in an ARRL radio handbook. Not having one here is a problem. Try searching VFO frequency readouts, that might be the key words.
Hope this helps.
Jack Crow tdy in Kuwait
Hi all,
You guys put me back about 25 years.
There are/were chips avalable that did an automatic offset correction with the right jumpers set.
Years ago I worked for Mr Kahn of AM Stereo Fame, and some of our early conversion radios (pre PLL days) were of the LO being a standard tuner and a frequency counter chip. You could select standard offsets to be applyed to the reading.
So if your radio was a high side injector, a normal counter chip would see 118.4 mhz. The chip would subtract 10.7 and display 107.7.
The same deal if it was a 'low side' injector radio.
You still see these counters avalable today on some CB radios. In transmit they read 'direct' and in receive the display the LO +/- some value.
Some 'comercial' tuners still use the VFO style receivers and have digital readouts. Might pay to get a peak at the service manual and copy a design that works. Then again some car radios are so cheap that for 25 bucks, you can take the parts you want and scrap the rest.
Ive also got a vauge memmory of just such a circuit being avalable in an ARRL radio handbook. Not having one here is a problem. Try searching VFO frequency readouts, that might be the key words.
Hope this helps.
Jack Crow tdy in Kuwait
George,
I can't find any paper in my file cabinet to support what I said. My last move I threw away boxes of papers because I didn't want to move them again. I even gave away my old tube manuals and Radio Amateur Handbooks.
However, there is an example of a good design which supports what I said at http://rfdesign.com/mag/radio_highperformance_fm_receiver/index.html . I am curious about why the designer made certain choices, like the passive mixer.
Regards,
Ray
I can't find any paper in my file cabinet to support what I said. My last move I threw away boxes of papers because I didn't want to move them again. I even gave away my old tube manuals and Radio Amateur Handbooks.
However, there is an example of a good design which supports what I said at http://rfdesign.com/mag/radio_highperformance_fm_receiver/index.html . I am curious about why the designer made certain choices, like the passive mixer.
Regards,
Ray
Hi Ray
It is O.K.
Don't look any further. Probably it was a miss-understanding from my side.
I anticipated your wording in post#30 as a reference to a theoretically derived minimum number in tuned RF stages and filter IF stages. This can't be so of cource if the tuning/filtering characteristics of each stage are not specified. And these characteristics depend on various aspects of a practical implementation, so much that a theoretical approach can not envisage all.
The link you provided on the above post is a good example. Loose coupling for one (implemented by distant placement of the coupling coils). Implemented coupling coefficient is always in question, thus the choise between tuning for maximum signal versus tuning for minimum distortion.
Looking at this topic from a practical point of view, the former is implemented with a minimum of instrumentation, while the later requires more sophisticated set-up and a rigorous procedure.
Passive mixer was probably a good choice on this design, after the designer amplified/isolated the LO section with two active stages.
Regards
George
It is O.K.
Don't look any further. Probably it was a miss-understanding from my side.
I anticipated your wording in post#30 as a reference to a theoretically derived minimum number in tuned RF stages and filter IF stages. This can't be so of cource if the tuning/filtering characteristics of each stage are not specified. And these characteristics depend on various aspects of a practical implementation, so much that a theoretical approach can not envisage all.
The link you provided on the above post is a good example. Loose coupling for one (implemented by distant placement of the coupling coils). Implemented coupling coefficient is always in question, thus the choise between tuning for maximum signal versus tuning for minimum distortion.
Looking at this topic from a practical point of view, the former is implemented with a minimum of instrumentation, while the later requires more sophisticated set-up and a rigorous procedure.
Passive mixer was probably a good choice on this design, after the designer amplified/isolated the LO section with two active stages.
Regards
George
Hi George,
I should have explained further when I commented on the passive mixer. Phillips has the TDA1575 IC which contains a mixer, oscillater and IF amplifier. See http://www.semiconductors.philips.com/acrobat_download/datasheets/TDA1575T_CNV_3.pdf . This could replace all the discrete circuits in the design except the RF stage. I don't understand why he used a descrete oscillator, mixer and IF amp when he could have used a single IC to perform the same functions and greatly simplified the design.
Regards,
Ray
I should have explained further when I commented on the passive mixer. Phillips has the TDA1575 IC which contains a mixer, oscillater and IF amplifier. See http://www.semiconductors.philips.com/acrobat_download/datasheets/TDA1575T_CNV_3.pdf . This could replace all the discrete circuits in the design except the RF stage. I don't understand why he used a descrete oscillator, mixer and IF amp when he could have used a single IC to perform the same functions and greatly simplified the design.
Regards,
Ray
Now this looks like an interesting DIY FM receiver project at http://www.loewenkatapult.de/ .
My German isn't very good so I can't read too much on this site.
Regards,
Ray
My German isn't very good so I can't read too much on this site.
Regards,
Ray
VHF tuner
I have a VHF tuner kit made - works OK in mono. In stereo the left channel is a lot louder. The measured L/R voltages reflect this . How to fix this problem ? I have replaced the ICs and tested OK all the parts around them but problem remains. The design includes a Colpitts oscillator.
1. Is it an alignment problem ?
2. Is it a stereo decoder problem ? The stereo LED lights for stereo and stereo sound appears. There is a pot for aligning the stereo decoder - a Toko87BN135BX2, 2mH. Adjusting the core of this pot does not appear to do anything.
The circuit is from Practical Wireless UK 1974 - CA 3089E, CA 3090AQ.
This 30 year old design seems to give a better sound than my Meridian G91 tuner - bass in particular, so I'm keen to hear it working properly!
I have a VHF tuner kit made - works OK in mono. In stereo the left channel is a lot louder. The measured L/R voltages reflect this . How to fix this problem ? I have replaced the ICs and tested OK all the parts around them but problem remains. The design includes a Colpitts oscillator.
1. Is it an alignment problem ?
2. Is it a stereo decoder problem ? The stereo LED lights for stereo and stereo sound appears. There is a pot for aligning the stereo decoder - a Toko87BN135BX2, 2mH. Adjusting the core of this pot does not appear to do anything.
The circuit is from Practical Wireless UK 1974 - CA 3089E, CA 3090AQ.
This 30 year old design seems to give a better sound than my Meridian G91 tuner - bass in particular, so I'm keen to hear it working properly!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.