Narrow-Bandwidth Television Association

The venerable CA3306 may soon be a thing of the past. It's a 6-bit analogue-to-digital converter that can sample at up to 15MHz with a simple parallel data output. It has been used often for converting 525/625 to NBTV, SSTV or whenever FSTV needs converting to another format. It's now considered obsolete and not so easy to obtain these days. A pair can be cascaded to get a 7-bit output.

It appeared in Peter Smith's 625 to NBTV 30/32-line converter, CQ-TV 189, year 2000, and also in the NBTVA newsletter around the same time, Vol. 25 No. 3. There are more modern replacements, and generally of at least 8-bits, but they're either expensive and/or in SMD packaging and possibly static sensitive. The CA3306 is in a 18-pin DIL package - easy for us lot.

I've got a few items on my 'NBTV TO DO' list, an update of Peter's converter is one of them. I did make a start on this in 2013, but something must have interrupted me. This has floated to near the top of the list as I'm going to need a source of NBTV soon...quite urgently in fact.

The reason for this posting is a local supplier has around 60 CA3306's in stock, I imagine that once gone, that will be it! They're made by either Harris, RCA or Intersil, though it's pot-luck whichever you get, they should all be the same functionally anyway. Cost? Thai Baht (THB)102.00 each inc. local VAT, =GBP2.37, US$2.98. A 'centralised distribution point' in the UK would make sense and reduce postal costs from Thailand to the UK.

Those interested in getting a few let me know and we'll try and organise things. Anyone care to act as the 'centralised distribution point' in the UK? I will test all before shipping.

As an aside, there was an 8-bit version, the CA3308, but no luck with finding a supplier of those...

Datasheets that I have for the CA3306 attached...

...also one for the CA3308 for interests sake, be sure not to mix them up, the type numbers CA3306 and CA3308 look very similar at a quick glance...

Cricklewood Electronics in the UK list the CA3306, but "Not available at present. Please check at later date." I doubt they ever will be available now...and no price mentioned either...

It appears that the LM1881 FSTV sync-separator is going the same way, it has been replaced by a version that can also handle HDTV. Time to stock up on those while you can...

Steve A.

Steve Anderson wrote:...also one for the CA3308 for interests sake, be sure not to mix them up, the type numbers CA3306 and CA3308 look very similar at a quick glance...

Just remember that the final digits are the number of bits.

...a follow on...

The replacement for the LM1881 is the LMH1980 from TI and others. It on paper appears to be a better device all-round for standard 525/625 and also handles various HD formats. Downsides - it is more expensive, though not outrageously so. BUT, it's in a SMD package of 10 pins with a 0.5mm pitch! As good as useless to us!

Steve A.