[alwayslearning]

Hi. New to the group and vacuum tube radios as a whole so please help me with each of my questions.
Recently purchased a 87 Highboy Deluxe in pretty decent shape and want to make it sound good. Being a newbie i plugged it in and started messing around with the knobs not knowing what i was doing. I luckily was able to pull in a station though hum and loud buzz/static dominated.

I've since replaced all the steady state caps with 630v film types hoping to get better results. I reinstalled all the tubes to then find out that if one replaces (or i assume swaps) one of the 26 tubes a new alignment is in order.

Currently it still hums (not too bad) but loud buzz/static is very prevalent and now i'm up to two stations barely. So here are my questions:
1. I'm getting 42 volt AC with a multimeter measuring from the chassis to electrical outlet ground with just the plug in the wall - is this expected? It turns to 65volts AC when powered up. Of course if i run a wire from the chassis ground connector to the outlet ground it goes to 0 volts but my reception also disappears.
1b. How is one really/typically supposed to "ground" the chassis?
2. I'm also getting 120volts AC at the LOC terminal? Is this expected? If not - why? If so, what's the point?
3. not knowing if i got the 26 tubes back in their original position is an alignment and neutralization in order?
3b. Alignment procedure requires a 1300kHz source - function generator work? Set to how many volts output?
3c. Use an "output indicator across the speaker terminal" does this mean a volt meter?
That's all my current questions. Please help and provide suggestions...
THANKS!

[Radioroslyn]

Hi and welcome,

Here's a diagram for your set:    http://philcoradio.com/tech/images/87.jpg
At the front right side of the chassis there is a black metal box which terminals on the bottom. Inside it is where the filter condensers live for the power supply. Unsolder the connection on the bottom unbolt from the chassis. Place it in an oven in a pan lined w/foil for easy cleaning. Bake for 20min @225deg. Remove the bottom cover and terminal board. Use a large I hook, screw it into the center of the of the old condensers and pull! Remove all the innards and clean. Using the diagram rebuild this condenser bank with new 630v mylar caps. Reinstall and reconnect.
Question 1 Yes
1B  6' copper rod into the earth with clamp and wire.
1C  Most of the time grounding the chassis to a good earth ground will improve performance and improve signal to noise ratio. Connecting it to the houses wiring ground is not all that great as it is a long path to the actual earth ground outside. And there can be a lot of RF noise on the AC mains wires. At RF frequencies your romex looks looks like a big coupling cap winding though your house picking up interference from lights, chargers, and sorts modern electrical devises.
2  It's there to shock the H**l out out of you! Sorry wrong answer! Check that 31 has been replaced. The LOC terminal can be used as a connection to use your house wiring for the antenna, not a great idea these days but in '28 it was ok for local reception.
3  Depends. Does the set  break into oscillation when tuning?? If not the neutralization is ok.
3B No, RF signal generator or local station on or near that fq. 50-100microvolts or less
3C Analog AC volt meter set on it's lowest range.
My neighbor Jon did a great job on replacing those filter caps! http://philcoradio.com/phorum/showthread.php?tid=14665

GL
Terry

[morzh]

I would remove Cap #31 altogether and forget it ever existed. Bad idea.

[Radioroslyn]

It's in the can.

Terry

[alwayslearning]

Thanks Terry for your response.
I've already rebuilt the condenser can with 630v film capacitors - is that ok instead of mylar?
Check that 31 has been replaced...  If you're referring to the 0.015uF cap on the power input - yes it's been replaced with a film capacitor.  Should I just remove it as commented on by morzh?
3.  I know what oscillation means but maybe not in relation to AM receivers - can you elaborate?
Thanks,
Keith

[morzh]

Well...when the can gets addressed (it will get addressed, won't it? if not then....OK, it probably can work like that too) I would take it out.

[Radioroslyn]

Your welcome
Film or mylars are fine you don't want to use electrolytic caps in this supply as the ripple current will cause the input cap to short. It happened to my set after about 6 months of operation.

I wouldn't bother to remove 31. If you can't sleep at nite knowing that it's there you  could hook a low value resistor to bleed off any ac leakage between LOC and GND. Something like a few hundred ohms. On second thought you could unsolder the connection from the mains to the condenser bank rather than physically removing #31. That's too much like work! It is the .015mfd

Oscillation? Read squeals like a stuck pig across the MW band. If it's doing it you'll know it as you can't turn the volume down to control it.

If you would like to try a little experiment to improve the audio frequency response try adding a .005 mfd/630v cap across the top of #22 (audio transformer) In other words from the junction of #24 and #22 to the grid of the 26 tube. If it does help you can play with the value by making it smaller or larger.

Terry

[alwayslearning]

Your welcome
Film or mylars are fine you don't want to use electrolytic caps in this supply as the ripple current will cause the input cap to short. It happened to my set after about 6 months of operation.

I wouldn't bother to remove 31. If you can't sleep at nite knowing that it's there you  could hook a low value resistor to bleed off any ac leakage between LOC and GND. Something like a few hundred ohms. On second thought you could unsolder the connection from the mains to the condenser bank rather than physically removing #31. That's too much like work! It is the .015mfd

Oscillation? Read squeals like a stuck pig across the MW band. If it's doing it you'll know it as you can't turn the volume down to control it.

If you would like to try a little experiment to improve the audio frequency response try adding a .005 mfd/630v cap across the top of #22 (audio transformer) In other words from the junction of #24 and #22 to the grid of the 26 tube. If it does help you can play with the value by making it smaller or larger.

Terry

Terry,
So I'm still confused on the function generator vs rf signal generator device.  I have a function generator which is good to 5MHz so 1300kHz is easily produced - would that not work?  I do know that it's minimal output is 5mv though.  Suppose I can put it through a voltage divider to get it down to your 50-100 microvolt specification?
Thanks - Keith

[Radioroslyn]

My understanding is that a function generator is used to generate different types of waveforms to check distortion and linearity in conjunction with a oscilloscope.
A signal generator generates a rf carrier (or modulated carrier) at a specific frequency. If your generator can produce a clean modulated carrier @1300kc then your OK. Truth be told you could use a local broadcast signal on or near that frequency.
But what the heck do I know??

Terry

[Arran]

I would remove Cap #31 altogether and forget it ever existed. Bad idea.

Mike;
  I agree, whilst it may work in principle, even with a brand new polyester film capacitor there will be some leakage from the AC line, not to mention that if someone touches that and the chassis at the same time!!! If my model 96 has this it's going to get disconnected, I am not Kirk.
Regards
Arran

[morzh]

Even if it is a Y-cap and no electrocutin 's likely, still there could be an unpleasant sensation.
If one is H**l-bent on using it, the value should go down to 2nF and Y-cap has to be used.