[Boatanchors] RCA 811K

[Carl]

I also have a 811K Bob.

If the electrolytics are not heating up and killing the B+ that is not 
the problem BUT they should be changed before you go any further unless 
you want to chance a fried transformer when they do let loose AND THEY 
WILL sooner or later.

The distortion is most likely all the paper caps, especially in the 
audio and AVC stages.

Start with the filters, you can use 20-22 uF safely, and then do 3-4 
paper caps at a time starting in the audio. Discs , mylar or poly film 
all work equally well, its not critical.  Then check your work and work 
back towards the RF amp.

The chassis is wide open so a recap is easy.

What is a PITA is the rotted rubber wiring but dont do anything with 
that yet except make sure nothing will short.

The motor drive will probably need to be removed, cleaned and lubed. I 
followed a procedure from a Google. More rubber wire also!

Once its recapped do a basic alignment but dont get fussy yet. Clean the 
bandswitch with DeOxit or Tarn-X and a Q-Tip, do not spray any of that 
stuff. I use a non conductive, no residue spray to remove the DeOxit or 
Tarn-X film that remains.

The rubber wiring in the RF area is length dependent so carefully 
measure and replace one at a time and check your work to be sure the 
alignment hasnt drastically changed.

You may find out of spec resistors and bad mica caps, just take it one 
at a time. Anything with Micamold on it is suspect.

Once its all aligned, the motor working and all good tubes the 811K is 
an outstanding performer, the speaker surround baffle really makes a 
difference.

Do you have the remote? Im looking for one.

Have fun!

Carl
KM1H


----- Original Message ----- 
From: "Bob Young" <youngbob53 at msn.com>
To: <boatanchors at mailman.qth.net>
Sent: Sunday, January 25, 2009 1:06 AM
Subject: [Boatanchors] RCA 811K



I brought up an RCA 811K console that I've had for a few years on a 
Variac tonight. I know it needs to be recapped, it use to hum pretty 
loud which is why I shut it off until I had the time to recap it which 
is now. Anyway the radio did not hum tonight but worked much better at 
approx 75 V than at 115, it got progressively more distorted, softer in 
volume and less sensitive when brought up to 115, when brought back down 
to about 75 it performed much better. (it did hum at first until I 
switched a bandswitch knob, the hum went away
as did the background receiver noise) Does this indicate that perhaps an 
electrolytic has shorted out? I didn't keep it on for too long, the 
power trannsformer was still cold along two of the cans, one was warm. I 
am going to replace all three but just thought I'd ask the group what it 
thought. I haven't pulled it apart yet, I'll also be replacing all paper 
caps and/or BB's.

Bob Young
Analog, MA
KB1OKL

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