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

38-690 Treble/Audio Bandwidth
#1

I recently finished restoring a 37-116 which is a really nice radio. What I noticed is that the treble response when adjusting the treble/bandwidth control is much better than my fully restored 38-690, so much so, that I question something is wrong with the 690. Having nothing to compare it too before, I felt it was fine until now.

I re-aligned the IF in the 690 and was able to balance the peaks while in wide band treble mode on both sides of 470 KHz as per the procedure. This made some difference, but nothing to write home about. The coupling capacitor for the tweeters was changed per Ron's write up and they sound like they are working well.

I also noticed a few things. Obviously the circuits are different in both. 1 vs 2 IF amps, and the treble pots in both radios configured differently as well. So It would be hard to compare the two based on this alone.
In addition, the treble control shafts have a different range of motion. The 37-116 has a full half turn vs only a quarter turn on the 690. This got me thinking maybe there is a mechanical issue with the 690.

My question to the Phorum is should I be expecting better from the 38-690? Does my observation about the treble control's physical range of motion have anything to do with this situation? Or is it simply they are two different radios with different audio reproduction and they are both normal? I'm hoping that those of you familiar with both sets will have an explanation.

Thanks in advance for your comments.

Tony

“People may not remember how fast you did a job, but they will remember how well you did it”


Messages In This Thread
38-690 Treble/Audio Bandwidth - by tbone - 03-09-2021, 06:37 PM
RE: 38-690 Treble/Audio Bandwidth - by rfeenstra - 03-09-2021, 09:43 PM
RE: 38-690 Treble/Audio Bandwidth - by morzh - 03-09-2021, 11:58 PM
RE: 38-690 Treble/Audio Bandwidth - by radiorich - 03-10-2021, 12:52 AM
RE: 38-690 Treble/Audio Bandwidth - by tbone - 03-10-2021, 06:50 AM
RE: 38-690 Treble/Audio Bandwidth - by rfeenstra - 03-10-2021, 02:03 PM
RE: 38-690 Treble/Audio Bandwidth - by rfeenstra - 03-10-2021, 02:18 PM
RE: 38-690 Treble/Audio Bandwidth - by morzh - 03-10-2021, 04:14 PM
RE: 38-690 Treble/Audio Bandwidth - by tbone - 03-10-2021, 07:29 PM
RE: 38-690 Treble/Audio Bandwidth - by rfeenstra - 03-10-2021, 08:38 PM
RE: 38-690 Treble/Audio Bandwidth - by morzh - 03-10-2021, 08:49 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Model 70 Cabinet Trim
musar , Well if you have any more questions feel free to post away . Sincerely Richardradiorich — 08:56 PM
Model 70 Cabinet Trim
Although I have not made any cabinets or cabinet parts for a couple of years, I still have some parts left over, includi...Steve Davis — 06:26 PM
philcorepairbench.com - shadow-meter
Thanks Ron.fenbach — 02:43 PM
Model 70 Cabinet Trim
Thank you, Gary. Before making my original post, I had clicked on "Steve Davis Cabinets" only to find that it...musar — 02:25 PM
philco predicta
Welcome to the Phorum, cgl18! I am not your resource for television repair, but lots of friendly help is available here...GarySP — 02:12 PM
Model 70 Cabinet Trim
Welcome to the Phorum, musar! You can send Steve Davis a private message (PM). The site is at the top of the Home page...GarySP — 02:09 PM
Model 70 Cabinet Trim
How do I contact him? The only contact information for him I could find when searching online was a telephone number th...musar — 10:38 AM
philco predicta
Hello, good afternoon, I would like to ask what the possible problem could be if I don't have an image on the screen. I ...cgl18 — 10:19 AM
Philco model 38 code 121 not receiving signal.
So one last question before I finish this radio. Regarding the speaker and output transformer. I salvaged the original o...Stormlord5500 — 09:31 AM
462ron
It’s on the bottom of the homepage of our Philcoradio.com homepage! Ron462ron — 07:20 AM

[-]
Who's Online
There are currently no members online.

>