RCAF AR88LF (GR-17) Project

[David Dunlop]

Here is a photo of the new AR88LF Speaker. Turns out to have been made in Canada and is fitted in the upper left front corner to accept a bakelite pocket watch holder. The model number on the data plate shows as MI-22201 which is the first one with this ID I have seen. The other model number I have run across is MI-8303D, but they look very similar. Strange.

The speaker cable is 1/4 inch rubber covering a pair of 16 gauge rubber coated conductors (one green and one black) and the packing in the rubber looks like the typical cotton waste of the 1930'as and 1940's. Be nice to find a source of supply so I can fit a cable back onto my other AR88 speaker.

David

[David Dunlop]

Hope everyone had a Happy Xmas and survived their New Year's celebrations.

I have been a bit too busy to get much done with the AR88LF, other than a bit of reading research. I found an interesting reference to there being a date of manufacture stamped somewhere on the chassis of the AR88 receivers in an XX-XX-XX style of format. Has anyone ever found this on their AR88, and if so, where was it located? The full year of manufacture seems to show up on the RCA data plates for this equipment, so it would be nice if RCA also included this information somewhere on the chassis.

I plan to get more photos of the disassembly and cleaning of the AR88LF posted in 2014! Promise!

David

[turretslug]

The date stamp is an intriguing suggestion but I'm sure that if something as unambiguous as this was widely present, it would be common knowledge (i.e. as well known as the serial number location). Could it have applied to just, say, Montreal-built 'LF models? Nonetheless, I'm prepared to be open-minded on the matter.

[QQVO6/40]

Anything is possible. I will have to have a look at my two later when I get home to see if there are any dates on them. I have a vague recollection of seeing a red date stamp on one of them on an inner chassis wall. I know that my SX-73 has a couple of date stamps in it but that is a Hallicrafters RX. I know, OT.
I do apologize to you David as I have not had a chance to get to doing the photograph thing yet. At the moment I am just on 4,000klms away from home in Western Australia. Doing some safety work for my son's company. Not sure when I will be home but this note is really to say I have not forgotten you and the other people here.

Cheers all for a very good new year.
Robert.

[David Dunlop]

Robert.

Not a problem on the photo. Your comment on the possible date stamp was interesting. When I read the article about it being found on an AR88 chassis, I simply assumed a metal punch style of stamp, into the chassis steel. A simple ink/paint stamp never even occurred to me, and that type of stamp would quite likely be very vulnerable if the set ever underwent a major cleaning/overhaul during it's service life.

Always great when a lot of heads on this forum are thinking about something.

Cheers for now,


David

[David Dunlop]

Well, it has been a good weekend so far. I found a supply of the cable needed to restore my second RCA AR88 speaker assembly. Baby steps, perhaps, but moving forward none the less.


David

[Station X]

Five posts moved to a new thread here:-

https://www.vintage-radio.net/forum/...d.php?t=102883

[David Dunlop]

Well, I have still not eaten enough spinach to try pulling the chassis out of it's cabinet just yet, but did want to post up a couple of new odd bits I have noted with my receiver.

Following a visit to the Radio Boulevard website covering the AR88 receiver series, I had discovered my receiver was missing the two rack slot covers which mount either side of the front panel, along with the round head slotted 12x24 machine screws that mount them in place. Photo from the RB site attached. Fortunately the RB site provided a detailed description of the two covers such that I will be able to visit the local metal shop and have a pair fabricated.

I wanted to document the four screws currently holding the chassis of my receiver to it's cabinet. Not sure if they even belong to the AR88 receiver series, but they do appear to be nothing more than larger cousins to the four knurled screws which fasten down the metal RF cover on the top of the chassis. The two on the top of the panel are nickel plated, the lower two are plain steel. Second photo.

While photographing these from an angle, I was surprised to discover the number '335' had been engraved with an impact pen on the upper right hand corner of the front panel. This would have been covered by the rack slot cover, had it been in place. This number a is simple free hand bit of work, clearly not done at the factory by RCA. Third photo.

What is interesting about this number is the fact the GR-17 Serial Number on the RCAF Data Plate on the front panel is '283'. That puts it close enough to (perhaps) be the original RCA AR88LF factory serial number. The full factory number would have been 'C-00335' and would have been stamped on the now missing data plate on the rear of the cabinet. Whoever removed the plate, for whatever reason, may have added the number to the front panel for future reference.

David

[David Dunlop]

Anyone know the correct shaft/thread length for the 12x24 machine screws that fasten the panel/chassis assembly into the cabinet? The large knurled screws currently doing this job on my receiver are 0.50 " in length, but I have no idea if this same length as the correct screws hold be.

David

[David Dunlop]

Well a short break from snow shovelling has finally taken place and I am getting closer to an initial powering up of the receiver to check existing performance. I am planning to use a simple linear aerial, but with the essential absence of the broadcast band in the AR88LF, can anyone recommend a band and frequency worth tuning to for checking reliable signal reception? Several options would probably be useful. More photos to come shortly.

Cheers for now.


David

[M0SOE_Bruce]

From Winterpeg you should be able to pick up the WWV time broadcasts. They are on 2.5, 5, 10, 15 & 20 Mhz. They are bang on frequency so are useful to check calibration as well.

The shortwave broadcast bands provide a good source of RF. List of freqs here:
http://en.wikipedia.org/wiki/Shortwave_bands.

Bruce

[Restoration73]

Would be interested in how reception is of CHU at your location. Always audible here,
often more so than WWV and an excellent propagation guide.

[Radio Wrangler]

Look up 'radio beacons'and you'll find a whole system of propagation monitoring transmitters sprinkled around the world. They're in amateur bands... just about all amateur bands now including 5.29MHz.

It's possible to sit on one frequency and listen to a sequence of beacons from all over coming on one at a time. Many do swept amplitude carrier for signal to noise measurement.

Another source of reliable signals is VOLMET, aviation weather broadcasts.

http://www.dxinfocentre.com/volmet.htm Gander is one of the most famous.

For your LF coverage, there are NDB (Non-directional beacons) used for air navigation by direction finding. They are still in use as a fallback system. Pilots still need to pass an exam in using them. There are usually NDB at airports.

http://www.dxinfocentre.com/ndb.htm

David

[David Dunlop]

Thank you gentlemen for the great suggestions. I will let you know how they go when I test the receiver.

I know I promised more pictures, and I will come through for you, in the meantime, however, I thought I would post the following link for you. It may initially seem a bit odd, but about 2/3's of the way in, an RCA AR88 Comm Receiver takes centre stage, so on that basis I think it fits with the thread.

http://www.youtube.com/watch?v=z-cVw7Xb6Nk

Cheers for now

David

[David Dunlop]

Hello again everyone. I would love to have been able to keep you all up to date with work on my AR88LF, but truthfully, nothing has been done for the last few months.

I was surprised last April with the interesting news I was the likely candidate for a wee bit of prostate cancer, After a handful of tests and consultations, the presence of the little beastie was confirmed and I was in hospital last month for the old snip and toss procedure. So far so good. They are confident it was all caught and removed and the healing and monitoring process is well under way.

During my appointment last week to get all the staples removed, the doc reviewed the list of 'Do's and Don'ts' I need to follow for the next few weeks. One of these items turned out to be the requirement I not lift anything more than 10lbs. "I can't do that!" I replied. "I own an RCA AR88LF!"

"And exactly what is that and how much does it weight?" my doctor inquired, his curiosity obviously piqued.

" An absolutely classic piece of wartime radio equipment." I stated confidently, "And it weighs just over 100lbs."

"Bully!" he shot back, while riveting me into line with a stare over the top of his glasses, only a practised surgeon of many years can perfect. "It stays put until further notice!"

"Yes, sir." I mumbled.

So please bear with me. The AR88LF adventure will be continued!

David

[QQVO6/40]

Hello David and everybody.
Prostate cancer. Not nice. Been there, done that, as they say, got the scars to prove it.
You will be ok. Always look on the positive side. Always!!!!!!!!
As for me, I have had kidney cancer since I last made comments of any substance. And likewise I have been banned from lifting anything heavy. (That definitely means my AR88LF and AR88D radios.) Along with a lot of other things I want to do. I thought I was going to be smart and do some things anyway in my workshop. Haha. I didn't count on the cook (My wife) dobbing me in to the doctor. Spies everywhere.
I will get to take some pics of the rear cover plate when I can rid myself of this medically induced hand brake.

Cheers, Robert.

[David Dunlop]

Hello Robert.

Love the hand brake concept! A temporary thing that serves a purpose as needed. My best wishes for you to be cruising down the highway soon. My two year old grand daughter lent me one of her Disney Princess dolls to keep me company while in hospital. I am definitely not an expert on these dolls at all, but my daughter told me this particular one was Aerial (?). How appropriate that turned out to be, as my grand daughter has never even seen my wireless kit!

David

[David Dunlop]

I have started looking at the 6V Supply Units for these receivers and have noticed three different RCA part numbers referenced for three different AR88 models (the D, LF and 91). There might be more out there, but I am curious as to why. Shouldn't one 6V Supply Unit work for any AR88 receiver?

David

[David Dunlop]

Any 6 Volt PSU's I have ever run across in this corner of the world have been missing major components, cables or been heavily hacked internally. In most cases as well, the ID plate is missing and if, in deed, these things are model specific for a particular AR88 receiver, lack of the ID plate could be critical. I have run across a photo of a complete 6 Volt PSU, which for all intents and purposes is generic to all of them. It is slightly larger than a Wireless Set No. 19 Spare Valves Box but weights 7 lbs on it's own. Add in the cables and you are probably pushing 10 lbs. The cable is 8 foot in length.
The three AR88 series receivers I have so far been able to ID matching PSU Models to are:

D: MI-8319
LF: MI-22215
CR-91: MI-8319-A

Four rubber feet are mounted on the bottom of the PSU chassis, but these csn be removed if the unit is to be bolted to a table. Critical thing is to ensure the vibrator stay as near to vertical as possible to function.

Thought I would post the photo in case this item has not been seen before by any of you.

Cheers for now, David

[Radio Wrangler]

http://www.radioblvd.com/ar88.htm shows photos of the CR88 with its trio of small knobs at lower centre and the crystal phasing control on the grey-painted front panel. The museum site says the CR88 was from 1947.

David