Newbie with an 800B

[Day Radebaugh]

Hello:

I'm Day Radebaugh from El Dorado, Kansas, and was happy to find this site.  30 years ago, when I was a starving student, I lived in a house in Baltimore that was in the process of being sold.  They had an old Scott console (with a phonograph, as i recall) which i bought for $5.  I couldn't keep the cabinet, but kept all but the phonograph.  It's been stored inside ever since.

So now I'd like to have it restored, and I would build a new console to contain it.  Do you have any suggestions about how to proceed?  Anyone you know of who could tackle a functional restoration of this unit?

Thanks for your help.

Day Radebaugh

[Day Radebaugh]

I've got that power transformer as far away from everything as it can be.  I can move it backward a bit, almost poking out the back of the cabinet.

[Day Radebaugh]

Here's a pic of the interior of that cabinet from the access hatch.  

Day Radebaugh said:

I've got that power transformer as far away from everything as it can be.  I can move it backward a bit, almost poking out the back of the cabinet.

[Dave]

Wouldn’t sweat either location Day. That bottom chassis pan should act like a nice radiator. This was a long haul, I like the results.

[Day Radebaugh]

Thanks very much, Dave.  A very long haul, but very worth it.  Appreciate your comments.

[Day Radebaugh]

I'm checking back in after weeks of enjoying and familiarizing myself with the 800B.  It's prompted me to refresh my understanding of circuits and electronics.  

I must say that Section IV Circuit Description (pp. 13-20) plus associated schematics of the Technical Service Manual for the 800B is an outstanding piece of work, and have helped me immensely.  Such documentation would be unheard of today, I suppose.

A question came up while studying this information and the Sam's Photofacts.  On p. 13 of the TSM, it states that 

and the Sam's implies that this transfer is done at the frequency of the tuned circuit of 600KC.

My question is how does this tuned circuit (600KC) transfer all AM frequencies to the subsequent circuits (oscillator and mixer), after which the frequency selection is accomplished?  I thought that the oscillator and mixer tuned to the desired frequency from the entire AM bandwidth.  

Thanks for your help.

[Thomas Day]

Hi Day:

I read thru the rf section of the tech manual. The RF tuned circuit frequency is set by the variable capacitor. As the capacitance value changes the frequency the circuit is tuned to also changes. Not sure where the Sams info gets the 600Kc info. This tuned frequency would depend on the combined resonant frequency of both the coil and the variable capacitor, which should change with the capacitor as it is tuned across the band. 

[Day Radebaugh]

Thanks.  As I understand you, the Sam's is just plain wrong.  This would make sense to me; I didn't understand how the full AM bandwidth could somehow be reduced to a single frequency, 600KC.

[Dave]

I concur with Tom, “tuned” frequency is not a constant. 

Not to wander, but since the 800b is rarely discussed, does anyone know of a source for the push button call letters ?

Thomas Day said:

Hi Day:

I read thru the rf section of the tech manual. The RF tuned circuit frequency is set by the variable capacitor. As the capacitance value changes the frequency the circuit is tuned to also changes. Not sure where the Sams info gets the 600Kc info. This tuned frequency would depend on the combined resonant frequency of both the coil and the variable capacitor, which should change with the capacitor as it is tuned across the band. 

[Day Radebaugh]

Thanks.  On my unit, the letters have been typed onto thick stock, then trimmed and inserted.  To duplicate the old look, you'd get MS Word and a color printer, and print them.  Would look great.

[Kent King]

I have some NOS station tabs. Are there particular ones you are looking for?

Kent

[Dave]

I have only the “ON” tab label so for starters would need “OFF” “AM”  “FM” and then anything to populate the “Station” buttons. Perhaps you have some such as WJR for Detroit but anything would do.

thanks Kent

[David C. Poland]

No such thing as an AM or FM tab label on an 800-B.

Rather - the push button tabs are rewired as FM or AM stations - study the documentation for how.

Closely spaced stations take careful planning on arranging the adjustable stops on the rear housing.

As rewired, each push button then controls the AM/FM relay in the receiver.

For the one I restored for someone, I made tabs on my printer, Brown for AM and Green for FM station call letters.

Factory had only 3 push buttons at the low end of the dial for FM. Today, probably want the majority wired for FM stations.

AS for your question above on the 600- KC  frequency, suggest you  to read up on how a Superheterodyne radio works and the use of an intermediate frequency amplifier tuned (for this Scott 800B) to 455 KC.