AM/FM receiver component question

[patrick398]

Not strictly stompbox related but i'll be putting this radio on my pedalboard so i guess it still counts ha.
I'm planning on making another radio receiver (TDA7000 didn't quite work out for me)
This circuit looks good, using the U2510B chip.

http://www.hadex.cz/img/zbozi/e833_2.jpg

I'm just a bit confused about the component between pins 14 and 18. I think it's a coil but i don't recognise the symbol. This is from the schematic on the U2510B datasheet, it lists a couple of parts numbers neither of which i can find. It also lists wire diameter and number of turns so could i just wind my own coil? Is this also what i'd do for the coil (L1) off pin 2?



Waiting on components for other projects so want to knock this together in the mean time

[patrick398]

Seems that the image upload isn't working for me atm

EDIT: although on closer inspection...

[GibsonGM]

Unknown symbol looks like a piezo crystal, buddy...they are used in oscillators to establish a solid frequency reference.  Gotta buy that, using the parts number.  It looks Russian; I cannot read it.

L1, your mystery coil at pin 1, seems to have a ferrite core. I would purchase that if you can.  I'll leave that up to an actual HAM radio person to come along and give their opinion as to whether it's something someone new should try and expect to get good results.  L1 appears to be an intermediate frequency transformer, which must be close for good results.

L2 and L3 appear to be 'air core' coils, and yes you can roll your own as long as the diameter and length are correct, if they are given....expect some drift from the nominal frequency if you DIY them, LOL....

[PRR]

The symbol implies a crystal IF filter. However the turn-count data implies an IF transformer.

If you can't find *much* better parts info, pass. You can buy a whole radio and strip the case for less than it would cost to ship the many special parts in a radio.

[patrick398]

Thanks for the replies guys! Some of this is very new to me so bare with me.
I would just go with the schematic on the ic datasheet but that seems to have even more potentially difficult to source parts. Also has a lot more vari-caps than i care to deal with.
I think i can find all the CF (crystal filters?) parts. Can i use any of those to replace mystery parts in the schematic i posted earlier?



In fact, i only really want the FM part of this so maybe i could just bypass the AM sections and save myself a bit of bother?
Also in the earlier schematic, pin 5 is not used, so perhaps i could eliminate another vari-cap from the datasheet schem

[amptramp]

You can get ceramic filters from Toko or Murata as the component between pin 14 and 18 in the first picture.  They are nominally 10.7 MHz and you can get them in various bandwidths and also as constant group delay filters that give better linearity.

In the last picture, you have ceramic filters for both FM (10.7 MHz) and AM (455 KHz).  The tuning capacitor is assumed to be a mechanical variable capacitor.

[bluebunny]

The Cyrillic translates to FP1P6, which you can Google.  The first two hits tell you "piezoceramic filter".  This is apparently what one looks like:

[EBK]

The Cyrillic translates to FP1P6, which you can Google.  The first two hits tell you "piezoceramic filter".  This is apparently what one looks like:

Looks like you might get away with substituting one of these:

[Les Turnbull]

I Think TOKO cans are are variable inductors but I don't think TOKO are still in business . There is a Toko and Mitsumi part no on this sheet .

[duck_arse]

in yr first circuit, i think C13.1 and C13.2 are the ganged tuning cap. which appears to be a four gang (good luck!) in the second circuit. it used to be that you could waddle into tandy/dick smith, maybe even jaycar, and buy a pack of IF/RF coils for a radio build. they were colour coded for which circuit position they were intended for.

[patrick398]

Ok so removing what i think are the AM sections and taking out the vari-cap off C5 i'm left with this...which if it'll work looks like a much more manageable task.
L1, L2, and L4 are all air coils so i can try roll my own. I've found CF2 on ebay and hopefully for T4 between pin 1&2 i can use the pac-mac monster from the first schem.
Funny how quickly the best intended plans become a mad scramble to bodge it all together
Thanks again for your help and suggestions

[patrick398]

Perhaps this will work for T4?

https://www.ebay.co.uk/itm/Keramik-ZF-Filter-Piezofilter-10-7-MHz-MuRata-SFE10-7MS3H-M/122873568024?epid=641611861&hash=item1c9bd5db18:g:JBwAAOSw0e9Uugr7