analog tuner receiver

[radium98]

question can you people help me figure this out to make it working ?
and what do i need extra to make this analog tuner to work
and what is the output i should have at IF this tuner is from a vcr and i need to make it here working on the uhf frequency band and take only out the audio .

20171101_222306.jpg

[Albert H]

You can't use it like a satcan!

Most TV (and VCR) tuner modules give out an Intermediate Frequency of around 45 MHz. It's also VERY broad (too wide for just audio) and if you try to use it without filtering it down, you'll have LOTS of noise along with your very quiet audio! Elektor magazine did a really neat General Coverage VHF / UHF receiver back in the late 80s, that used a TV tuner module driving into a 45MHz filter and a mixer stage to take it down to 10.7MHz - the rest of the receiver was then just a normal IF strip. You have to realise that analogue video bandwidth was close to 6MHz, whereas FM audio is about 180 kHz wide (for multiplex stereo).

Back in the 80s I used a TV tuner module with a separate PLL circuit driving into a dual conversion IF with a PLL demodulator. It could be programmed for any frequency from 47MHz to 960 MHz in 50 kHz steps. We made hundreds of these receivers for links - in quantity, they were really cheap to build. Lots of stations used them - often integrated into a receiver and exciter module - and it was a really neat "general" solution. They had Belling-Lee aerial input sockets, and the PCB was about 6½" X 4½". Frequency programming was done with solder blobs between tracks beneath the board. When these receivers were sold to people like Dawson, they were completely potted in epoxy resin so that he couldn't copy them! We included a relay output for rig switching.

[radium98]

Albert h can you provide a copy of that elektor or the number
I already built a 10.7 if demodulatot so i was thinking of combining that receiver thanks to mention that if out is around 45 mhz i was thinking it is just 10.7
I have uploaded a picture of the demodulator .
Please help me .

[shorty]

I've just looked for my copy of the elektor electronics magazine with that vhf/uhf tuner circuit, it must have got chucked in my last clear out, i'm sure it used a philips tv modulator, it's the October 1993 edition you need.

[radium98]

Yes please at shorty bte did u looked at the pm abot the rdvv hex you told.me about .i dunno and cant remmber if in old time i ws having this elektor magazine but if also i have i dont think i can do it for lack of components foes it need hex file .if yes please provide it .

[Albert H]

Albert h can you provide a copy of that elektor or the number
I already built a 10.7 if demodulatot so i was thinking of combining that receiver thanks to mention that if out is around 45 mhz i was thinking it is just 10.7
I have uploaded a picture of the demodulator .
Please help me .

The 45 MHz output is about 56 MHz wide as well! You have to filter at 45 MHz then downmix to 10.7 MHz (I used an NE602 with a 35 MHz crystal). I used critically tuned 45 MHz L/C filters, using an S18 White coil in each tuned circuit.

[radium98]

is ne602 replacebale by ne612 i can only get that i have one in my junkbox i see it can be equivalent ?
and what what about the tuner above i should tune it with pot extremely on the VT pin up to how much voltage ?

[yellowbeard]

I've just looked for my copy of the elektor electronics magazine with that vhf/uhf tuner circuit, it must have got chucked in my last clear out, i'm sure it used a philips tv modulator, it's the October 1993 edition you need.

Knew I read that. Part2 was in the november issue and I got the PDF files if anyone needs them.

[radium98]

I've just looked for my copy of the elektor electronics magazine with that vhf/uhf tuner circuit, it must have got chucked in my last clear out, i'm sure it used a philips tv modulator, it's the October 1993 edition you need.

Knew I read that. Part2 was in the november issue and I got the PDF files if anyone needs them.

Yes please upload it to see what i can do thanks

[yellowbeard]

I've just looked for my copy of the elektor electronics magazine with that vhf/uhf tuner circuit, it must have got chucked in my last clear out, i'm sure it used a philips tv modulator, it's the October 1993 edition you need.

Knew I read that. Part2 was in the november issue and I got the PDF files if anyone needs them.

Yes please upload it to see what i can do thanks

Here it is - it's a bit of a beast though...

Code: Select all

https://mega.nz/#!uAsQ3RCB!8Af-c-l_ZdBnZXm48mzJM4nw4ciio7rugo491xsj9V0