Skip, if you make a neutralizing adapter, be sure to make the interconnecting wires as short as possible. The adapter sockets and wires have capacitance between them, so it affects the interelectrode capacitance seen by the circuit.
Perhaps the most accurate method of neutralization is to insulate the filament pin of the actual tube used for each stage, one at a time. This way you are neutralizing the actual grid-plate capacitance of each specific tube and not adding any stray capacitance.
I usually wrap a small piece of clear Scotch tape on one of the filament pins for neutralizing. The tape is thin and doesn't interfere with inserting the tube in the socket, yet insulates the pin so the filament is not lit.
Ok Thanks.. Parts arrived today. A volume control that measures 9K instead of 65K like mine does.. And the adapters to make a socket for neutralization..
I put the adapters together and will try that first.. I will install the volume control this weekend..
I assume its better to have the chassis back into the cabinet before alignment.. I can access the parts from the bottom of chassis thru the holes provided..
OK tried the empty ball point pen plastic tube holder to align.. it didn't work at all seems its to small. I tried tried to soften it up and mold around nut That didn't work either...
If this is not a trimmer/padder that is under the plate (B+) voltade AND has to be accessed through a hole in the chassis, you could try to use a socket wrench, after each adjustment removing it and seeing if it changes and then adjusting it again a little to achieve the max, each time removing the wrench until the sig is peaked.
For those inside holes, with power off loosen them fist with the wrench making sure it could be moved without very strong effort, and then use the ball pen tube morfed hot after a nut of the appropriate size first.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
(This post was last modified: 09-09-2017, 10:15 AM by morzh.)
Ok Newer volume control installed. Works good.. Did RF alignment all went well..
Only problem is at 1440 Khz I have a station about 1 mile from me.. it comes in distorted.. No ,matter what I do..
It seems to be overloading the receiver..even with NO antenna connected.. maybe everything back in cabinet will shield it a little..
I did not attempt the neutralizing yet.. I think I will put the bottom plate back on and put in cabinet then check it .. Maybe it doesn't need to be neutralized.. We will see..
Back in the cabinet and an earth gnd connected to it should help.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Ok, all put together.. Pain to get the phono jack in without it shorting to chassis.
Works very good.. Distortion is gone at 1440 Khz now.. But slightly above that it motorboats.. I know how to fix that by detuning the last RF section..
I will take pictures of the unit and a video of it working..
Thanks
to all for the help to get this 1928 Radio back in working order..
Hi Skip.. I just purchased a 514 and need to find an aluminum power supply cover stamped with '514'. As you have a 512 which has the incorrect cover with 514, is there any chance i could purchase the cover from you and provide you with a 511 exact replacement? In just beginning my restoration. This will be my 6th set. I also have a 511 i restored which is one of my favorites. Thanks for considering
Mark 6099548084
Did you buy the one on Ebay last week?
I had a monster Esnipe bid on it,$500,but withdrew it at the last minutes.I decided I didn't need two 514's.
Phil
I did.. pretty decent unit (Got it for $160 with shipping.. not bad). I couldn't believe it was missing the power supply cover though. Now i just need to find the speaker wish which may take the rest of my life! Can't wait to start restoring it. Please let me know if you'd consider an offer for the cover you have.. id be very grateful. Cheers
Mark
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