27-06-2014, 09:15 AM
Most of the CCTV cables available today are of the figure-of-8 "shotgun" variety, so look like over-grown bell-wire. I assumed that wouldn't be appropriate for this restoration, which is why I spent about 15 minutes chasing down the variety I used 10+ years ago - being in one overall PVC cable. Also, the "shotgun" types tend to only have 2 cores (for power), which isn't enough. The stuff I used had a red/black pair for power, plus 3 smaller cores for audio and control. If only I still had access to the drum I bought all those years back - that was in my previous job...
Regarding screening, I'm of course aware about the vibrator PSU, but what is going to be susceptible to interference radiated from the supply? Obviously, the audio signal travelling down the bundle in very close proximity. But what else? Assuming this is to be fitted to a car of similar vintage, what other sensitive electronics will be present? Given that an exact copy is not available, this is where you have to put your "engineering" hat on, and ask yourself these sorts of questions. It's why I mentioned the impedances seen by the audio cable in my first post.
If screening of the HT pair is really important, and you don't mind have multiple cables inside braided sleeving, then things get a lot more interesting. There are a lot of cables that we use at work to carry balanced audio and control signals, and can be of quite decent current-carrying capability. For example, FST:
http://www.canford.co.uk/Products/31-001...pair-Black
This stuff is probably a bit thin (7/0.2), but what is the HT current? But a couple of runs of this (one for power, one for audio), plus one or two standard single cores for other functions could easily fit into braided sleeving of the right diameter.
It's worth spending a bit of time on the Canford site, as they have a massive range of cables, and they sell per metre...
Regarding screening, I'm of course aware about the vibrator PSU, but what is going to be susceptible to interference radiated from the supply? Obviously, the audio signal travelling down the bundle in very close proximity. But what else? Assuming this is to be fitted to a car of similar vintage, what other sensitive electronics will be present? Given that an exact copy is not available, this is where you have to put your "engineering" hat on, and ask yourself these sorts of questions. It's why I mentioned the impedances seen by the audio cable in my first post.
If screening of the HT pair is really important, and you don't mind have multiple cables inside braided sleeving, then things get a lot more interesting. There are a lot of cables that we use at work to carry balanced audio and control signals, and can be of quite decent current-carrying capability. For example, FST:
http://www.canford.co.uk/Products/31-001...pair-Black
This stuff is probably a bit thin (7/0.2), but what is the HT current? But a couple of runs of this (one for power, one for audio), plus one or two standard single cores for other functions could easily fit into braided sleeving of the right diameter.
It's worth spending a bit of time on the Canford site, as they have a massive range of cables, and they sell per metre...
