Vintage FM front end tuner Help? - UK Vintage Radio Repair and Restoration Discussion Forum

aurelZlatko · 25th Jul 2021, 8:38 am

hello
I want to build FM tuner front end posted by Argus25
https://www.vintage-radio.net/forum/...d.php?t=145179
it is with
AF124 preamp and AF125 osc/mixer...
I can read some values from document but not all because image is
blur and i simply cannot read whole component values
like in preamp is that 1.5k or 15k ?
also first caps is 33pF i can read but under that one i cannot
please any help or link to clear-er image
i really like to build this one because i have similar transistors
AF139
AF279
AF239
BF939
BF670
etc
thanks in advance

Herald1360 · 25th Jul 2021, 11:28 am

Hi, attached is a slightly better copy.

You can find it also in here:

https://frank.pocnet.net/other/Phili..._3_1971-11.pdf

See p48 of the pdf

HTH

John_BS · 25th Jul 2021, 12:08 pm

There are many designs for FM front-ends from that era: are you happy that this design is limited to 101 MHz?
John

aurelZlatko · 25th Jul 2021, 12:24 pm

Well in the document it's stated that it tunes from 88 to 108. I don't see 101?

But OK maybe I am wrong.

Thanks a lot for the link!

aurelZlatko · 25th Jul 2021, 2:56 pm

Ahh yes I see it now, but I think with some calculation could be changed to 88 to 108.

Well I would be happy if it worked and I expect good sound.

aurelZlatko · 27th Jul 2021, 6:00 pm

hello again.

I made a quick build of the above FM tuner and I have data about coils, but I don't know what is a coil inner diameter.
any advice?

John_BS · 31st Jul 2021, 5:26 pm

Try 12mm

John

aurelZlatko · 2nd Aug 2021, 3:29 pm

Ok i try with 10mm and not work well..ok i will try
with 10 mm
If that not work i wil use varicaps BB109 on 3V and 11 & 10 turns of 0.5
on 2.5mm diameter ..that must work!

orbanp1 · 3rd Aug 2021, 12:43 pm

For some ideas look at the Technics ST-930 receiver, though it uses an eight-gang tuning capacitor.
Here is a good article on it with analysis and modifications:
http://www.ham-radio.com/k6sti/st-9030.htm

Regards, Peter

25th Jul 2021, 8:38 am	#1
aurelZlatko Diode Join Date: Feb 2014 Location: Slavonski Brod, Croatia. Posts: 6	Vintage FM front end tuner Help? hello I want to build FM tuner front end posted by Argus25 https://www.vintage-radio.net/forum/...d.php?t=145179 it is with AF124 preamp and AF125 osc/mixer... I can read some values from document but not all because image is blur and i simply cannot read whole component values like in preamp is that 1.5k or 15k ? also first caps is 33pF i can read but under that one i cannot please any help or link to clear-er image i really like to build this one because i have similar transistors AF139 AF279 AF239 BF939 BF670 etc thanks in advance

25th Jul 2021, 11:28 am	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Vintage FM front end tuner Help? Hi, attached is a slightly better copy. You can find it also in here: https://frank.pocnet.net/other/Phili..._3_1971-11.pdf See p48 of the pdf HTH Attached Thumbnails __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

25th Jul 2021, 12:08 pm	#3
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,779	Re: Vintage FM front end tuner Help? There are many designs for FM front-ends from that era: are you happy that this design is limited to 101 MHz? John

25th Jul 2021, 12:24 pm	#4
aurelZlatko Diode Join Date: Feb 2014 Location: Slavonski Brod, Croatia. Posts: 6	Re: Vintage FM front end tuner Help? Well in the document it's stated that it tunes from 88 to 108. I don't see 101? But OK maybe I am wrong. Thanks a lot for the link!

25th Jul 2021, 2:56 pm	#5
aurelZlatko Diode Join Date: Feb 2014 Location: Slavonski Brod, Croatia. Posts: 6	Re: Vintage FM front end tuner Help? Ahh yes I see it now, but I think with some calculation could be changed to 88 to 108. Well I would be happy if it worked and I expect good sound.

27th Jul 2021, 6:00 pm	#6
aurelZlatko Diode Join Date: Feb 2014 Location: Slavonski Brod, Croatia. Posts: 6	Re: Vintage FM front end tuner Help? hello again. I made a quick build of the above FM tuner and I have data about coils, but I don't know what is a coil inner diameter. any advice?

31st Jul 2021, 5:26 pm	#7
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,779	Re: Vintage FM front end tuner Help? Try 12mm John

2nd Aug 2021, 3:29 pm	#8
aurelZlatko Diode Join Date: Feb 2014 Location: Slavonski Brod, Croatia. Posts: 6	Re: Vintage FM front end tuner Help? Ok i try with 10mm and not work well..ok i will try with 10 mm If that not work i wil use varicaps BB109 on 3V and 11 & 10 turns of 0.5 on 2.5mm diameter ..that must work!

3rd Aug 2021, 12:43 pm	#9
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	Re: Vintage FM front end tuner Help? For some ideas look at the Technics ST-930 receiver, though it uses an eight-gang tuning capacitor. Here is a good article on it with analysis and modifications: http://www.ham-radio.com/k6sti/st-9030.htm Regards, Peter