AR88 Rewiring

[thoyer454]

I have heard that some AR88 had been rewired after a period of time way back when..... I have two, an AR88F and a CR88 that are basket cases (flood victims) and I'm going to "restore" them. Part of this process will involve replacing the disintegrating wiring harness. I'm very familiar with these radios and have the skills / test equipment / spare parts to do this task.

I've researched cloth covered wire but am unsure if this is the right way to go. I work in the aerospace industry and could use the MIL spec wire we use in our harnesses but that would not be "period correct".

So my question - when these radios were rewired back in the day, what kind of wire was used?

Tom
W3TA

[HamishBoxer]

As they are not rare, I would use the Mil spec wire,

[G6Tanuki]

Yes, in the period after WWII quite a number of the AR88 receivers in Military service were rewired in PVC by various Services base workshops, so I would have no qualms about using similar current 'mil spec' wire for your rewiring.

My AR88 - one of the early ones - had crumbly cotton-covered wire when I bought it some 40 years ago. I rewired it using PVC covered wire salvaged from the wiring-loom of a crashed car.

[Radio Wrangler]

I have an AR88 which was rewired back in the early fifties. The wiring is PVC insulated. According to labels, REME did the job. PVC is a bit too meltable to be easy to use in this application. If you have Kynar or similar aerospace insulated wire in a variety of colours, go for it. It will not look wrong, and your task will be a lot easier.

Despite the refurb, mine is an early set with engraved panel, all-yellow dials, and S-meter.

David

[cathoderay57]

Since they are flood victims then I'd strongly recommend testing the inductance of all the coil windings, HF, Osc, IF, BFO, AF and mains transformers. Rewiring is a substantial effort, and you wouldn't be best pleased to fire it up eventually and then find that one or more coils had gone south. Jerry

[thoyer454]

Good suggestion - will do. pwr xfmr, audio and chokes all are good. I'll run through the other ones prior to installation - I have some spares in case.

Tom
W3TA

[thoyer454]

I ordered a bunch of MIL Spec wire today from our supplier. I'm off of work between Christmas and New Years and plan dive into it then. In the mean time, I'm checking my inventory of caps and resistors and ordering what I may need.

Should be interesting. I rewired an SP-600 many years ago. Took some time, but it worked.

Tom
W3TA

[Radio Wrangler]

That looks good, Tom.

So you already know what to do with bathtubs!

I'd be tempted to put labels on all the connections coming out of the AR88 harness, then snip all the connections and remove the whole harness. Make a pin board to spread it out on a lump of plywood and then use the pinboard to make up the full harness with longer lengths to allow for connections, and then do a neat lacing job. Putting labels on the ends of each wire as built to match the labels written on the board.

It's a lot of work, but produces a neater result.

I believe the re-wired AR88s were done this way, REME had a job lot of harnesses made up and in they went.

It's harder these days because the colours of the cotton outers have faded away, so the labelling becomes the critical issue. Lacing is so much easier and neater on a board.

David

[G6Tanuki]

Yes about making a pin-board to help fabricate the new harness. Also worth getting a bunch of the small coloured/numbered heat-shrink sleeves and using them to number/code the ends of the individual wires - this is handy even if you _are_ using some sort of colour-code for the wires.

My wire colour-code goes something like:

Green: LT
Red: HT
Black: Earth
Brown: Unregulated 'reduced & decoupled' HT for RF/IF screen-grids, low-level audio stages etc
Purple: Regulated HT for oscillators
Yellow: AGC line
White: RF/IF cathodes to gain-controls
Audio wiring is blue.

[thoyer454]

Good call on the pin boards. I was conjuring up something like that in my mind.

I have already removed the harness - intact - so I can use that as a model to lay out the new one.

Labels will be used.........

Years ago I used to deal with a local yacht manufacturer. In their wireshop they had full scale peg boards to lay out the harnesses. Once all dressed they'd load them on a pallet and a fork lift would take them out to the assembly line. Impressive to say the least.

We developed a DC power control system (Remote Electronic circuit breakers controlled over a CAN bus) for the aviation industry but our first few customers were in the marine industry. The customer I mentioned above did a study and using our system saved them over 700lbs of wire.

But I digress.....

Next I need to find someone that can refinish the front panel. Needs to be stripped, painted and screened. I'm half tempted to try it myself but the last time I silk screened something was back in elementary school.......

Tom
W3TA

[thoyer454]

Originally Posted by G6Tanuki

My wire colour-code goes something like:

Green: LT
Red: HT
Black: Earth
Brown: Unregulated 'reduced & decoupled' HT for RF/IF screen-grids, low-level audio stages etc
Purple: Regulated HT for oscillators
Yellow: AGC line
White: RF/IF cathodes to gain-controls
Audio wiring is blue.

All colors I have ordered. Yes, I do need to develop a code. I was going to use brown for the filaments - got a good deal on some 18ga brown and the wires the harness look "brown-ish" for the filaments.

Tom
W3TA

[thoyer454]

Originally Posted by Radio Wrangler

That looks good, Tom.

So you already know what to do with bathtubs!

Yeah, in this SP-600 I restuffed them, I don't think I'm going to do that on these radios. I'll install terminal strips and mount the caps to them. Typical of what I've done on the other RCA's I've had my hands in.

Tom
W3TA

[John Caswell]

Colomor Radio in Goldhawk Road Shepherds Bush W12 used to offer AR88s rewired in PVC for I think £75.00, That was a lot of money in the 60's
John

[Vintage Engr]

Originally Posted by John Caswell

Colomor Radio in Goldhawk Road Shepherds Bush W12 used to offer AR88s rewired in PVC for I think £75.00, That was a lot of money in the 60's
John

Colomor are still going! I actually spoke to the person there earlier this year, & also remember them being in Goldhawk Road.
They are in Billingshurst now, & sell everything from valves to underpants! I doubt if they've any AR88's now.

David.

[Radio Wrangler]

You never know with that sort of firm. They could have all sorts of things stashed away. Just think of John Birkett's.

David

[David G4EBT]

Incidentally, I don't know if any AR88 fans on the forum have seen the Western Historic Radio Museum AR88 website? It was created by American radio amateur Henry Rogers - WA7YBS Radio Boulevard/WHRM. (The WHRM was a real museum "Open-to-the-Public" from 1994 to 2012 - eighteen years of operation).

It's a very comprehensive website devoted to the AR88:

https://radioblvd.com/ar88.htm

Hope that's of interest.

[thoyer454]

One of my AR-88's is pictured on his website - showing a model with the non-textured front panel. Also the CR88 with the green and stainless legends front panel.

Henry has done a lot of research into MANY radios. You can spend hours browsing his website. A great resource.

Tom
W3TA