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

Model 80 Mods
#1

Making progress on my model 80. It is playing well and the voltages seem more in line now that I can check them with a VTVM. At a later date I think I will need an alignment to peak performance. I receive stations all along the dial range. However there is one station on the 150 dial location that is very strong, but very distorted.

Following Ron's mods: I have changed resistor #9 to a 13k 3 watt. Changed resistor #16 to a 2meg. Now I'm getting ready to change the connection of resistor #5 and cap#6 with respect to their connection to the antenna coil. Which brings up the question of the "gimmick". In the performance modifications on his website there is one wire with three turns wrapped around the volume control wiper lead and then connected to the cathode of the detector-oscillator tube. Simple enough, but then I found an earlier post on the subject where there were two wires. One connected to the cathode of the detector-oscillator tube the other wire connected to the volume control center tap with the free ends overlapping about an inch and twisted together. Which is correct? Then It dawned on me I have a model 84 sitting here as a next project. Different still. That gimmick wire is indeed wrapped around the volume control wiper lead, but then is connected to the oscillator-transformer. Photo below is my model 84 with the solder tool pointing to the connection.

While the radio is playing there is a definite boost in volume if I touch my finger to the shaft of the volume control. Is this what the gimmick is intended to do?


Attached Files Image(s)
   
#2

What it does is add some osc signal (from the 36's cathode) to the input of the mixer. This improves the ability to the mixer to handle stronger signals without overload and generally improves the mixing action.
By touching the volume control you are asenually are bypassing it and adding more rf signal, that's why it gets louder.

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

I completed all of the mods recommended. It plays and receives stations all across the dial, but reception is really not improved. If anything it is worse as I need a longer antenna wire with the radio upstairs out of the basement. There is also a hum like a florescent light interference which wasn't there before. Maybe it just the time of day, but 700 WLW is just a stones throw away and I thought reception would be better. Maybe I did something wrong? Icon_confused




Users browsing this thread:
[-]
Recent Posts
philcorepairbench.com - shadow-meter
Anyone know of a way to recover these files from the repair bench? Thanks. fenbach — 11:16 PM
Philco model 38 code 121 not receiving signal.
That's true. Of course If I were to get a vtvm I'd probably have to sink money in to it to get it working right. Probabl...Stormlord5500 — 08:44 PM
Philco model 38 code 121 not receiving signal.
A DMM is good enough. One rarely has to measure indictance, but if you do, short of getting a serious LCR meter (I hav...morzh — 07:35 PM
Testing a speaker and output transformer Trutone A2-G
You guy's are right on. I found a broken wire on the speaker plug that I replaced and all is well now. Have better volu...murf — 03:43 PM
Philco model 38 code 121 not receiving signal.
I need to get a vtvm. I think that little component tester is just more accurate. Plus it shows the inductance which is ...Stormlord5500 — 03:07 PM
Philco model 38 code 121 not receiving signal.
I use a pair of Mastercraft brand DMMs from Canadian Tire, from what I read most of those DMMs use the same main chip re...Arran — 02:36 PM
Philco model 38 code 121 not receiving signal.
Thank you sir. Yes I feel good and also relieved because this one's been weighing on me a bit.Stormlord5500 — 11:18 AM
Philco model 38 code 121 not receiving signal.
It feels good don't it? Good luck on the rest.Paul Philco322 — 11:06 AM
Philco model 38 code 121 not receiving signal.
I've reinstalled the coil. Now IT'S ALIVE!!!!!! I fired up my TinySA on signal generator mode and set it to 1400Kc and ...Stormlord5500 — 11:01 AM
Philco model 38 code 121 not receiving signal.
Yes, Walmart, right up there with Fluke.RodB — 11:00 AM

[-]
Who's Online
There are currently 2143 online users. [Complete List]
» 3 Member(s) | 2140 Guest(s)
AvatarAvatarAvatar

>