6MHz intercarrier sound circuit request

[biker_bob]

Hi All,
Does anyone know of a 'simple' 6MHz intercarrier sound circuit?
I'm looking for something I could knock up on vero-board / strip board or maybe dead bug style. Preferably locked to 6MHz rather than free running.

The reason is that I have a 23cm analogue video tx that has an input for the intercarrier but not the intercarrier itself. I have put a 6MHz sig-gen into the port and get the local repeater to fully quieten. The TX is free running so having a KNOWN 6MHz audio source helps to tune up the main TX as the repeater goes silent when on frequency.

I borrowed the sig gen from work so need to return it following my tests.

Any pointers much appreciated.

[g8vpg]

Bob,
Have a look at the BATC Wiki, ATV equipment manuals section, Solent/Worthing ATV TX. This has a simple 6MHz sub-carrier generator (free-running, but quite stable in my experience) with input amplifier capable of being driven by a mic.
73 Shaun G8VPG.

[biker_bob]

Thanks Shawn.
DO you, or anyone, know of a suitable replacement for the BB204 Varicap diode pair? That seem to be about the only component that's no longer around.
Cheers,
Bob
G1XIE

[gm1mfn]

The MV104 from On Semi looks very close. It appears to be available from Mouser in the UK.

[biker_bob]

Sadly also obsolete (

[gm1mfn]

There's a surface-mount device available from Farnell. Unfortunately it's 46.5pF rather than 42pF but that might be close enough.

[keng8vdp]

Thanks Shawn.
DO you, or anyone, know of a suitable replacement for the BB204 Varicap diode pair? That seem to be about the only component that's no longer around.
Cheers,
Bob
G1XIE

Its a bit of a late reply but try ebay ..theres a few BB204 s listed

http://www.ebay.co.uk/sch/i.html?_from= ... e&_sacat=0

[biker_bob]

Thanks for all the responses.
It's been a while and I can't remember what I used in the end but I did get it working.