Hello all,
I am working on restoring a Howard SG "A" radio/amp and am having trouble reading the schematic's lettering of components. The page in question is Riders 1-6. The top schematic on the page. Specifically, I would like to find the values for 5 capacitors shown on the schematic. The capacitors are:
1: Middle 24 tube, cap from cathode to ground
2: Middle 24 tube, cap from screen grid to ground
3: 27 tube, cap from cathode to ground
4: Middle 24 tube plate connects to transformer primary. Follow other primary lead down ant there is another cap to ground
5: On the dual volume control second half, there is a cap from the wiper to ground and is electrically parallelled across the cap in #1 above.

If anyone can ID these values for me it would be very much appreciated. Thanks.
Dean

:Hello all,
: I am working on restoring a Howard SG "A" radio/amp and am having trouble reading the schematic's lettering of components. The page in question is Riders 1-6. The top schematic on the page. Specifically, I would like to find the values for 5 capacitors shown on the schematic. The capacitors are:
:1: Middle 24 tube, cap from cathode to ground
:2: Middle 24 tube, cap from screen grid to ground
:3: 27 tube, cap from cathode to ground
:4: Middle 24 tube plate connects to transformer primary. Follow other primary lead down ant there is another cap to ground
:5: On the dual volume control second half, there is a cap from the wiper to ground and is electrically parallelled across the cap in #1 above.
:
:If anyone can ID these values for me it would be very much appreciated. Thanks.
:Dean

For more information. I found the part numbers from other schematics. The Howard part numbers of the capacitors are P-1802, P-1803, and P-1804. By looking at other Howard Schematics, I found that a 1802 is a .5mfd, 1803 is a 1.0 mfd, but still at a loss for the 1804.

Hi, Dean.

First a question - I wonder why Howard did not show component values on the schematic, just Howard part nos? Oh, well. Schematic at: http://www.nostalgiaair.org/PagesByModel/055/M0040055.pdf

Regarding the value of cap 1804. This cap is in parallel with 1803, which you have determined is a 1uF, correct? (Double check that.)

These two caps seem to be serving as a cathode resistor bypass for the three RF stages. I don't know why 1uF isn't plenty sufficient, unless there is some RF issue involving the physical arrangement of the wiring. Maybe some of the gurus here can shed some light on this.

But anyway, I'd try a 0.1uF for cap 1804 and see how it works.

:Hi, Dean.
:
:First a question - I wonder why Howard did not show component values on the schematic, just Howard part nos? Oh, well. Schematic at: http://www.nostalgiaair.org/PagesByModel/055/M0040055.pdf
:
:Regarding the value of cap 1804. This cap is in parallel with 1803, which you have determined is a 1uF, correct? (Double check that.)
:
:These two caps seem to be serving as a cathode resistor bypass for the three RF stages. I don't know why 1uF isn't plenty sufficient, unless there is some RF issue involving the physical arrangement of the wiring. Maybe some of the gurus here can shed some light on this.
:
:But anyway, I'd try a 0.1uF for cap 1804 and see how it works.

Hi Doug. Thanks for the help. I will try a .1 and see what happens. I don't know why they would have them installed in parallel like that except it probably has to do with shielding issues, as the two caps are in separate compartments of the radio. As far as the schematic goes, it is weird that they only put the Howard part numbers down instead of the values. If you look at the other Howard schematics a lot of the older ones do the same thing. Unless you have a parts list from Howard, you are pretty much sunk except for guessing. Thanks again!