My 23cm ATV Station
Go to my Portable ATV page for progress on my alternative station.
before I dismantled it!.
This page started on 21/04/03.
(Please also see the 'ATV Project' pages for more equipment.)
24 cms ATV.
Click on one of the 4 main units in the picture for more information.
(Click for: larger picture OR block diagram of: Front end or IF to output)
This was originally designed by G8CMQ in 1984 but has many mods added to it since then, mostly suggested by Mike G8LES. Click here for an inside view of mine. I have recently fitted my own preamp but originally I had an 'LMW' preamp in the space at the left hand end. I have now replaced it with my own preamp but, at the time of this photo, it was outside the RX just visible at the back left hand corner of the RX. Now the antenna socket goes straight into a G8CMQ designed front end/mixer in the diecast box (with lid removed). The tunable IF is a Mullard ELC1043 TV tuner, which I have arranged to tune, at the antenna, 1240MHz to 1320MHz with a 270° turn of the Tune knob. The baseband IF output at 38MHz is demodulated by a PLL IC (NE564). This gives the added facility to give an apparent control of bandwidth. The sound demodulator also uses a PLL IC (NE564) and has a varactor tuned frequency range, set on a front panel control, of at least 5.5 to 6.0 MHZ. To save front panel space I used just one meter switched to indicate: subcarrier frequency setting / main tune frequency / signal strength.
I added a 'Buzz filter' circuit (click to see board) on a sub board which puts the video signal into the audio amplifier. This can be very useful for instance, when out portable, as it enables you to adjust beam heading by ear whilst out of view of the monitor. I also added a PCB circuit to give three independent video outputs eg. for: monitor, VCR & video to an ATV TX for relaying (say, on 13cms). Just recently (April 2003) I added a line sync detector PCB (click to see board) to provide audio squelch (to save damaged eardrums & loudspeaker when a local closes down!). It is similar to the various published designs using an NE567, such as: CQ-TV 200 p42, VHF Communications 2002 Q4 p232, Johannes DL4EBJ's design... and so on.
(Click for: block diagram) - Sorry for low quality.
||Move cursor to 3 areas of the TX to tell you what they are.
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(Click for: pictures - Sorry, not yet available.)
The G4WIN, Forrester TX
(My 2nd, portable, TX.)
Go to : ATV Add-ons (click for details)
where, eventually, details on most of the following will be provided:
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- "Low cost caption generator" by Steve Drury G6ALU.
- "4-Input Vision Selector" from the ATV Compendium.
- Video fader & audio mixer CQ-TV.
- "PIC Caption Generator" by Alain Fort.
- "Test Card Generator" The "Cropredy".
- "Video Distribution Amp" using discrete circuits.
- "VOGAD" using the obsolete SL6270.