The second 800B tuner has arrived..
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Just today. Odd, since this is the part that was oversize and came via Parcel Select. The amp chassis arrived in Seoul this afternoon, so I should get that tomorrow.
Minor damage to the preset mech on the back. One side bent in slightly, should be a simple fix.
This one's been totally recapped. They didn't restuff the cans, just disconnected them and installed the new caps. Not a bad job, really. But they missed something: the plate resistor for the RF amp was measuring about 1.3 megohm rather than the 15K called for. Replacing that gave me great gain on AM/BC, but there's a disconnect somewhere between the detector/AVC and the eye tube, as there is no indication whatsoever despite the tube appearing to be almost new. I will put another tube in there and see if there is any difference, just to be sure.
SW is dead. No LO at all. When I switch from BC to SW, the plate voltage drops from ~129 to around 103, but I don't think that would kill it completely. Have to try to figure that one out. Feeding a signal in from my sig gen does result in good reception on the band, so if I can get that LO going, it should do very well. If anyone has experience with this particular problem please feel free to toss in your two cents.
FM seems pretty good on this one. Much better gain than on the other tuner, there's even some white noise between stations as there should be. Still not quite what it should be, though, as it will only partially close the eye tube on a very high signal, it barely moves at all with an average input. I kind of suspect perhaps weak IF tube or tubes. I have some on order, so we'll see on that.
All buttons work properly on this one. Once I get that preset mech bent back into shape, I'll try my hand at setting up some presets. Nice to be able to turn it on and off.
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Brenda, turning on and off is a real comfort. Not fun to have to pull the plug. That radio is quite sensitive and the best for picking up stations that I have. Our location is not ideal. I have about a 20ft. wire inside the house for AM and a dipole on the roof for FM. Locals (not many) will close the respective eye tubes. Could your 1 meg resistors have gone high?
I have not tried the SW other than knowing it works. May try it tonight and see what I can get. I doubt you will like the tone controls they really suck. Norman posted a change on it and I have done that on 3 800s. It really makes a difference.
Good luck, now that you have two of them, the body building course will continue. Only nice part is that all three components are plug in so they are easy to separate.
Jerry
A friend in need is a pest! Bill Slee ca 1970.
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Do you have a link to those tone mods? I agree, there isn't much tone control, maybe +/- 3 dB or so, just judgeing by ear.
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Brenda, they are probably buried a long ways on ARF. Might be easier to PM Norman. It really makes a big difference.
Jerry
Edit: BAD, try this link.
http://ehscott.ning.com/photo/albums/sco...rt-cabinet
The only thing I changed was his addition to the resistor/cap strip shown and used the one can that was removed and stuffed the proper cap in there. I didn't want to try to add an additional lug to the strip.
A friend in need is a pest! Bill Slee ca 1970.
(This post was last modified: 11-19-2013, 10:15 PM by jerryhawthorne.)
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Thanks, Jerry. I printed those out and will work on that this evening. Maybe I'll get lucky and my tubes will be in the mail today as well.
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Amp for this tuner came in today. It, too has been recapped. FM IF train needed to be aligned, but now the set has good strong reception on both bands.
I did end up opening the 6E5 sockets up and changed out the (very high reading) 1M resistors in both. The AM eye now works 100% perfectly. The FM eye is much more sensitive now, but still only closes a maximum of about 40%.
I discovered that I have a few unresponsive selector buttons, mostly on the right side. I'm sure this is a simple matter of cleaning/adjusting those pushbutton switches.
Haven't worked on the tone control circuits yet, but will get around to that soon.
REALLY P****d myself off tonight. A bottle of glue fell off the shelf and right into my speaker ![Icon_sad Icon_sad](https://philcoradio.com/phorum/images/smilies/icon_sad.gif) What was a pristene speaker is now a patchwork mess.
Posts: 1,107
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Well, well...
Found the SW problem with this tuner today, basically completing troubleshooting and all but completing repairs.
Turned out to be the trimmer cap for the SW band. It's one of those frame type caps, and the plates were all rubbing, so shorting out the LO.
Nearly drove me nuts trying to find the trouble on this one, these type caps don't generally have those sorts of problems, especially when they're pretty much covered up. But, shorted it was. When I opened it up all the way, the LO came to life.
I've got a temporary replacement in there just to make sure that I could properly align the band, which was pretty simple except that my temp trimmer is a much higher capacitance than the original and so very temperamental to adjust.
I've PM'ed Norman to see if he has one I can buy. But, I guess I can say now that I have a working set of 800B chassis, soon to have a pair of them. ![Icon_smile Icon_smile](https://philcoradio.com/phorum/images/smilies/icon_smile.gif) Guess now I have to start getting creative about a cabinet for at least one of them.
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Sounds like you moving right along Brenda. My first 800B had two of those caps closed, killing the FM. It appears that the someone tried to adjust them using the nut and not the screw in the middle of the nut. The nut is a compression type and not threaded. Both air caps had to be removed to press the nut back on to hold the plates in proper alignment.
Jerry
A friend in need is a pest! Bill Slee ca 1970.
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