Hi BA gang,
Today a nice RCA AR-88D receiver (WW-II era) has arrived (thanks to Engbert Oord, who found it in England, bought it, checked it and has carried it to my home in Spain in his car. Besides, we have enjoyed today a very nice time here. Thanks Engbert!).
The AR-88D is in its original cabinet and, as a big plus, has the original S-meter!. With the receiver, I have also got an speaker. It is not the original one, but very similar looking, enclosed in a black metal cabinet with a front panel of 22 x 23 cm and a 12.5 cm depth. Also, a very good copy of the User's Manual was included, along with an spare tube set. And the small allen key used to remove the knobs is at its support in the chassis; Engbert missed it until today, as it is an small one, barely noticeable.
The serial number of this unit is 000703 ... As there were lots of AR-88s made, I wonder if this could be considered an 'early unit'. Comments welcomed!.
Here you have information taken from Engbert's report (a very nice work,as you can see!):
= (START of REPORT) ==================================================
The chassis is very clean.The face is in black wrinkle paint with silk screened labels. Again no dents,scratches or rust. The labels have slightly faded, but are still very legible. The RCA emblem is still present. All knobs are present, original and unmarked.
1. An extra tumbler switch underneath the most left hand rotary switch knob. It is used to switch the receiver on and off. It can easily be removed and the hole be blanked with a push on piece of black plastic. I have done the same for one of mine, it is hardly noticeable.
2. An extra earphone socket
3. At the backplane an additional antenna plug has been fitted in parallel with the antenna connection on the tagboard.
To compensate for these minus points : the receiver is fitted with an original S-meter. This is unusual. I have never seen one with an (original) meter before.
Both chokes, the mains transformer, the AF output transformer and the smoothing capacitor are still original. Be warned that the AF output transformer is a weak point due to the very dodgy design of the AF output stage. I will give you a copy of an article which points out the weak points and how you can fix them.
Unusually this RA-88D has a 6V6 in the output stage, according to the circuit diagram it should be a 6K6. The 6V6 in this receiver is correct, as the label on the chassis says the same.
The receiver is in working order and receives on all bands. Yesterday I removed the bottom cover (also in excellent shape) to inspect the wiring. As far as I could see it is all original except for the already mentioned small mods. Only one of the oil filled bath tub multiple capacitors has been replaced. All others are still in place, however some of them are leaking oil. You are well advised to replace them all.
I tested all valves :
6V6 20 /45 50% candidate for renewal, but still works okay
6SJ7 2.7/3 100%
6SG7 10 /11.8 100%
6SG7 7.6/11.8 70%
6SG7 could not remove it, hands too big
6SG7 8.2/11.8 95%
6SG7 8.0/11.8 95%
6SA7 5.5/12 75% a bit down on Ia, but still good emission
6J5 6.5/9 100%
6J5G 3 /9 65% this is a glass one, should be a metal valve
1-st column : valve
2-nd column : expected Ia
3-rd column : measured Ia
4-th column : measured emission
= (END of REPORT) ====================================================
As Engbert had already checked the receiver and I didn't see any apparent trouble, I have changed the 6J5G (glass) for a 6J5 (metal), put a new power plug, fitted the speaker and the antenna and then... IT WORKED :-)!!!. All bands are operative. I don't know yet if the sensitivity is on specifications, but SW AM signals come clear and loud.
Thanks to Engbert and other BA List members, I have collected a number of AR-88 documents, taken from different sources (RCA manual, Radio Bygones, Internet WEB pages, The Short Wave Magazine, Electric Radio, RCA Tech Memo, ...). It is nice to read how much appreciation exists for this 50+ years old receiver. I am beginning to know why!.
Well, that's all for now!. I will take some pictures soon and will put them at my WEB page. Stay tuned!.
Best wishes for 1999!
While looking at the documents I have about the AR-88 receiver, I have found that there are (at least) two different front panel versions. In fact, I have access to another unit (in a local Radio Museum) and it has the other kind... They are easily differentiated as one has (apart of other differences), in the 'RANGE' control, the frequency coverage of each band besides the band number (1 to 6). And the other version have just the band number. My unit is of this last kind.
In the documents I have, there are samples of both kinds (in my manual copy the one shown is the same as in my AR-88D). I wonder if you know when (or, perhaps, 'where', if these receivers where made in different locations) the different panels were introduced or manufactured. Is it possible to date the receiver by this characteristic?. I know serial number is 000703, but I can't find any date code...
And now THE B I G SURPRISE !!!. The receiver HAS an ORIGINAL ADJUSTMENT TOOL !!! (so not all the tools are orbiting around Saturn ;-) ). When I got the set, it had two tools attached with plastic adhesive tape to the RF unit cover; one is blue plastic and obviously newer than the receiver. But the other is brown, has two metallic tips and seems lots older. Then, once I have opened the RF section cover, I have found that it fits perfectly on the smaller tool holder :-)!. As the receiver had also the small allen tool, I am only missing the big tool in the RF cage... Perhaps some day I will find one ;-) ;-). Can I dream a bit ???
Thanks for all you help.
Best regards and H A P P Y 1 9 9 9 ! ! !