Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Old / Newer Sig-Gen output values
#1

Still fairly new at tube type radio repair. Just completed alignment on an Olympic model 411. Was impressed with it's final sensitivity and volume. Decided to use it to preform my first stage gain measurements to both increase my knowledge of stage operation and strengthen my troubleshooting skills. Ran into my problem fairly quickly when instructions guide me to adjust my sig-gen output to 3500 microvolts.  That value is a bit difficult to locate on my HP 8640B. Had read some where many months ago of a difference between older and newer sig-gen output terminology and values. Seems my search engine skills are lacking worse than my sig-gen skills. After considerable time at research my success was zero. Could someone please give me a heads up on conversion from old to new terminology and values.

Take Care

Tim
#2

3500 microvolts is a ridiculous amount of signal. A decent average sensitivity for a run of the mill 5 tube BC set will be around 40-100 microvolts. Would think if it was badly out of alignment maybe double that to start out to do the alignment.
Generally what I do is feed the the IF signal thru the grid of the mixer tube (with the generator set @ the IF frequency). Set the output level so I can just barely hear it. Adjust the IF for max speaker volume or minimum avc voltage. As it gets louder and louder I turn down the generator's level. Set the oscillator @ the top end of the BC band. Peak the ant trimmer.

GL

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!

Terry
#3

Thanks Radioroslyn, I have aligned the radio and am happy with it's performance. What I'm trying to do is establish the  gain of the Second AF, First AF, IF and Converter stages. Following the instructions in the Elements of Radio Servicing by Marcus and Levy. I have tuned many solid state radios so I have the experience to make up my own intake, output values to determine each stage gain. Just for my own enlightenment and entertainment I am trying to  follow the instructions that a tech would have followed over 70 years ago. When the instructions make reference to the 35000 microvolt level of input from the RF Sig-gen I had a small amount of memory recall of something I read on a thread some where, that made this statement. The word microvolt 70 years ago did not mean 1\ 1000000 but rather some other value. If I am wrong, please let me know. Don't want to be jumping down a rabbit hole because of a foggy memory.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Zenith H725
I just remembered, I have some hi temp silicone rubber material which could do the trick. Or a piece of FR4 laminate. Th...EdHolland — 08:39 PM
Zenith H725
The PSU filter cap arrived today (thank you USPS!) so I will work on that later. Meanwhile, I have the dial, speaker...EdHolland — 06:42 PM
Philco 610B oscillator wiring
Thanks Terry. After checking my notes I think I recorded about -10v at the 6A7 G4/control grid. The screen grid (G3 &...Tubester — 05:59 PM
The list of my radio & TV collection!
Magical chords of forgotten melodies, old nostalgic music on an old radio... Saturday night blues on the Mid-Waves on an...RadioSvit — 12:20 PM
Philco 42-345 Restoration/Repair
Thank you MrFixr55 the issue with this radio is that the internal coil antenna is missing and there was a wire in its pl...osanders0311 — 11:34 AM
Philco 610B oscillator wiring
Regarding the oscillator circuit which is comprised of the 6A7's cathode, control grid, and screen grid. These elements ...Radioroslyn — 10:33 AM
Philco 42-345 Restoration/Repair
Hi OSanders, First off, welcome to the Philco Phorum where Phine Phamily-Phriendly Pholks Phull of Philco Phacts and P...MrFixr55 — 08:41 AM
Philco 42-345 Restoration/Repair
Today I've been reading through the site trying to learn more about this radio. I also soldered the lose power cord cabl...osanders0311 — 08:24 PM
Philco 610B oscillator wiring
Thanks David! I do have that same later prodution model 610 schematic. I've also studied the Philco service bulletins fo...Tubester — 08:12 PM
Philco 610B oscillator wiring
Some info from Beitmans says late production. David   David — 06:06 PM

[-]
Who's Online
There are currently 1827 online users. [Complete List]
» 3 Member(s) | 1824 Guest(s)
AvatarAvatarAvatar

>