Early 116B alignment questions - Printable Version
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Early 116B alignment questions - govee - 01-02-2020
I posted on another forum and got a lot of reading traffic but no responses so I thought I would ask here as well. If I get an answer here I'll copy it to the other forum.
I have finished the electrical restoration...I think... I noticed that in the BC band I get a high pitched whine/squeal from about 1100 KC down to 55 with no station reception. The whine disappears above 1100 and I pick up stations. I did not notice this on any SW band. Not sure if I need to check anything else before doing the alignment?
I have the instructions from Philco and Riders and I have a few questions. I have only done 1 alignment it was a year ago and don't remember how.
First:
1. Sig Gen set to 460KC modulated with 400hz, dial at 55, select BC range,turn down 2nd IF trimmer no. 54
2. connect sig gen without coupling cap to the grid of of the first IF tube with the grid cap wire removed.
3. I am suppose to connect the meter to the plates of the output tubes. I believe that to be pin 2 of the 42 tubes. Probe and ground on opposing tubes pin 2 with the meter set to AC and on the 0-30v scale
correct?
Second:
1. Connect Sig gen to the Antenna (replace grid cap wire on 1st IF) varying the freq and band switch as instructed, turn down wave trap trimmer no 1
The Riders has a note when moving the sig gen for this to use a 200 mmF condenser dummy antenna for BC and 400 ohm resistor for all SW. Is this saying put a 200mmf cap between the anntena jack and the sig gen when aligning BC steps and a 400 ohm resistor when aligning sw?
2. There is no mention of out meter placement being moved so I presume it stays as above?
Thanks,
Andy
RE: Early 116B alignment questions - Jake Blake - 01-02-2020
Welcome to the Phabulous Philco Phorum Andy!
RE: Early 116B alignment questions - Radioroslyn - 01-02-2020
Hi Andy and welcome,
Grew up in MD abt half way between Baltimore and Washington.
>Not sure if I need to check anything else before doing the alignment?
I would check the voltages (plate and screen) around the rf and if stages and see if there are any anomalies. Another critical one is the plate voltage on the osc (76 tube). Make sure you have the shields on, didn't reverse the grid caps on the rf amp/mixer tubes and that the 77's and 78's are in the proper places they look the same. Is the shadow meter coil open?
There's a small chance that the alignment may stop the squealing issue but want to see if all the other circuits are more or less working, at present they aren't.
RE: Early 116B alignment questions - govee - 01-02-2020
Jake,
Thanks for the welcome
Radiorosyln,
i am near the end of the world in Southern MAryland near Saint Mary's City. Thanks for the advice. I will be checking the voltages.
If the voltages are correct is my understanding (represented by the questions in the OP) of the alignment instructions correct?
Andy
RE: Early 116B alignment questions - Radioroslyn - 01-03-2020
I use to get out to PNAS, Snow Hill, and Assateague Island from time to time back in the 80's for a company I was working for. Do they still have that big old auction in Crumpton I think it was called Dixons?
If it checks out ok then I would proceed w/the if alignment.
>
1. Sig Gen set to 460KC modulated with 400hz, dial at 55, select BC range,turn down 2nd IF trimmer no. 54
Yup that's what it sez.
connect sig gen without coupling cap to the grid of of the first IF tube with the grid cap wire removed.
Personally I wouldn't I would just connect the signal to the ant post.
3. I am suppose to connect the meter to the plates of the output tubes. I believe that to be pin 2 of the 42 tubes. Probe and ground on opposing tubes pin 2 with the meter set to AC and on the 0-30v scale
correct?
You don't want pin 2 of the 42's anywhere near ground as they are @ +300dc, your 80 will hate you[Image: https://philcoradio.com/phorum/images/smilies/icon_twisted.gif] to say nothing of the output transformer and field coil. To extract some ac voltage from the 42 use a large mylar cap like 2mfd @600v to connected to pin 2 the other end of the cap to the ac volt meter. The other lead of the meter connects to the chassis.
1. Connect Sig gen to the Antenna (replace grid cap wire on 1st IF) varying the freq and band switch as instructed, turn down wave trap trimmer no 1
The Riders has a note when moving the sig gen for this to use a 200 mmF condenser dummy antenna for BC and 400 ohm resistor for all SW. Is this saying put a 200mmf cap between the antenna jack and the sig gen when aligning BC steps and a 400 ohm resistor when aligning sw?
Don't know never used one.
There is no mention of out meter placement being moved so I presume it stays as above?
Yes would stay as first connected.