Bakelite block question-66MB
Posts: 289
Threads: 55
Joined: Mar 2007
City: Toledo
State, Province, Country: OH
According to the 66MB schematic, the block #26 is suppose to be 2 100pfd caps but the part number, 8035-B says they are 110pfd caps. Also, the resistor, #25,is suppose to be a 50K but the resistor in this is a 51K. Also the parts list says a 50K but gives the color code green-brown-orange which clearly says its a 51K. So whats correct?
Posts: 411
Threads: 42
Joined: Sep 2008
City: Ironton Ohio
It may be a revised code there so close that it shouldn't matter either way
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
110 pF is generally no longer a standard value. While the original 8035-B would have had 110 pF caps inside, 100 pF mica caps will be fine as replacements.
Resistor (25) can be replaced by 51K, no problem. I have seen this as well as a parts list calling for 100K but the radio has a 99K inside, and vice versa. Philco pulled these sort of stunts in the mid-1930s.
--
Ron Ramirez
Ferdinand IN
Posts: 289
Threads: 55
Joined: Mar 2007
City: Toledo
State, Province, Country: OH
OK, didn't have enough 100 pf to make a complete block so I cobbled together a 47 and 56 to get a 103 pf, actually measured 102, and a 100 to complete the block. I'll put in a 51K to match what was actually in the radio. Now, only things left are find that replacement 6UF can capacitor and get my speaker reconed.
(This post was last modified: 02-15-2013, 09:17 PM by Jim Dutridge.)
Posts: 289
Threads: 55
Joined: Mar 2007
City: Toledo
State, Province, Country: OH
Another question, what type of bulb was used in this radio? This has a holder I've never seen in a radio before. Not a bayonet or screw base holder but, for lack of a better word, a clip-in style holder. I was thinking maybe a 44 but its an awful tight fit as far as the height goes.
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
{Ron - 110 pF is generally no longer a standard value...}
FYI, 110pF. is a standard value in dipped silver-mica types.
Mouser has them:
http://www.mouser.com/ProductDetail/Corn...eSkK7fk%3d
Probably overkill for a post detector tweet filter, but I happened to have some on last block I needed them for.
Chuck
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
Very interesting, and I stand corrected! There was a time when I could not find 110 pF mica caps, and I don't think even Mouser had them at the time. Oh well.
There is a page I was thinking of, where the author, wa2ise (who is a Phorum member) advocates the use of 33 or 47 pF caps in place of the old 100 or 110 pF caps:
Quote:Another thing you should address is the small RF filter caps on the audio output of the detector. Have them too big and you can get tangent distortion because they take too long to discharge to allow a full amplitude 5KHz sine wave thru without getting tangent clip. Change the (usually) 100pf caps to around 33 to 47pF.
http://pw2.netcom.com/~wa2ise/radios/feedback.html
I've replaced 110 pF micas with 33 pF micas in some of my own sets since reading this tip a few years back. They did no harm, although I don't have any fancy test equipment to measure the difference.
Perhaps wa2ise will jump in here with some comments of his own.
--
Ron Ramirez
Ferdinand IN
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
If you are not hearing any fidelity issues, then it won't be a problem.
Chuck
Posts: 80
Threads: 10
Joined: Apr 2012
City: Waterford, NJ
Jim,
I believe a 44 bulb is correct. Unfortunately, I took a spill on the ice and can't get to shop due to resulting injury. Hopefully, in the near future, I will check the 66 and get back to you if you still need the data on the bulb. I remember it being a tight fit.
Joe
Posts: 289
Threads: 55
Joined: Mar 2007
City: Toledo
State, Province, Country: OH
Thanks for that information Joe. Thats what I put in was a 44. Still need my 6UF can cap.
Users browsing this thread: 1 Guest(s)
|
Recent Posts
|
Jackson 715 not working
|
Mrfixr55, its working now. I cleaned the switches and sockets with spray cleaner. Thanks for helping on this one.daveone23 — 06:26 PM |
Jackson 715 not working
|
Now that you posted the schematic, I don't know why that Sprague electrolytic cap is across the meter, as it is not indi...MrFixr55 — 05:51 PM |
HiFi (Chifi) tube amp build - but my own design.
|
What may be lacking in the PP Tube amps may be the 2nd harmonics, which some, especially RCA back in the day called &quo...MrFixr55 — 05:32 PM |
Jackson 715 not working
|
Usually in an emission tester, the tube under test is measured as if it were a diode. So, some testers connect all the g...RodB — 04:17 PM |
Restoring Philco 37-604C
|
Yep. F5 is green, D5 is Red.
Red is Bad.
Green is Clean.morzh — 01:30 PM |
Jackson 715 not working
|
I did start to do that but I stalled out because I could not figure out how the grid and plate get voltage. In this diag...daveone23 — 11:52 AM |
Restoring Philco 37-604C
|
(Insert Homer Simpson "DOPF" Here.)
When all fails, look at the can. Took the Ron Ramirez advice, red Caig D...MrFixr55 — 09:23 AM |
Philco 91 Speaker Replacement
|
From your text I am not sure if you intend to use the existing speaker with a resistor instead of the field coil.
It wo...morzh — 08:44 AM |
Philco 91 Speaker Replacement
|
My field coil is bad. I am still hoping to find an original, but if I can't I will go with a fitting Philco speaker, 125...dconant — 08:34 AM |
Philco 91 Speaker Replacement
|
As Rod said, it is OK to use a fitting speaker, and then look for an original one.
If you buy a Hammond 125 output tr...morzh — 08:15 AM |
Who's Online
|
There are currently no members online. |
|
|