EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

Hi Kent:  I am working on a Shield Grid 9 now that is in very good shape. I have dismounted the SGA (shield grid assembly) because of low filament voltage on the three 22s - max I can get is 2 volts with 5 volts on the entry bus.  Taking that SGA off and opening it was much more of a chore than necessary because the designer apparently didn't think it would ever be required.  The paperwork discusses the short wave ability of the SG-9 and the need to change the coil in the 630 Antenna Coupler copper box (+ the .0008 added capacitor).  Only one of the 4 copper housings has 2 bolts mounting it to the bakelite.  Do the covers of the other three copper housings pull off? or how do they come off?  Is desoldering the lugs from under the chassis to free the assembly required?  The bakelite is so fragile that I don't want to apply any damaging pressure.  Any ideas/help greatly appreciated! 

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Comment by Steve Larrabee on April 4, 2017 at 3:10pm

Thanks, Norman:  I'll make some presentable shields, ground them and then cover them with the very nice copper lid of the SGA -- and only 550 people will know.  best,

Comment by Joseph W Strickland on April 4, 2017 at 3:31pm

Steve;

Here is one source for large OD aluminum tubing in shorter lengths at reasonable price that I use:

https://www.dxengineering.com/parts/dxe-at1506, Aluminum Tubing, 6063-T832, 3 ft., 2.000 in. OD, 0.058 in.Wall, No Slit, $6.60 each. The ID should be more than the typical 1 13/16 OD of a globe tube like the 01A types. They also have the same length in an OD of 1.875 but the ID I am not sure about.

Joe

Comment by Steve Larrabee on May 21, 2017 at 9:52pm

I apologize for the apparent drop off on this topic - I could have sworn I wrote a closing comment after I got the SG-9 going in mid-April.  I had the SG-9 working very well with delicate tuning of both tuning shafts running separate variable condensers + 1 for the RF and one for the oscillator .  By matching the dial scales on both, and then tuning the matched dials together, I was picking up stations quite well - some near and some far away.  The tuning was quite broad and careful manipulation of the variable caps and the RF tube filament voltage controlled the oscillations. I ran the 22s at the 3 volt max which was full CW on the right side rheostat - with 6vdc in for A+. I ended up using aluminum foil around the glass on the 22 tubes in the SGA -- they are not seen with the SGA copper cover installed.

This set was a challenge but also a marvel when you consider this was the 1928 real thing from  the Scott Transformer Company of Chicago, ILL.  A pleasure and thank you all again for the help!

very best, steve

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