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

40-155T Add Aux Input Questions
#6

Hi Tgr131,

First off, It looks like your enthusiast friend did rather nice work. I like the coil on the end of the new cap. Looks like it would act as a "socket", holding it in place. This technique would minimize heating existing joints.

Your technique would work. In fact, my RCA 14BT1 battery "farm" Set (1.5 / 90V Batteries) had the phono jack installed by RCA in the exact manner.

Better fidelity can be obtained by breaking into the audio circuit by installing a SPDT switch as follows:
Break the connection between C38 (the input to the Audio Amp) and the junction between R39 and R37D (the output of the Detector). Connect the common pole of the SPDT Switch to C38. Connect one switchable leg to the junction of R37D and R39. Connect the other leg to the Audio Jack that you are using. Use shielded cable if necessary but ground the shielded cable between the switch, detector output and audio amp input at only 1 point to prevent ground loops. If the audio jack is not grounded to the chassis, connect the ground terminal to the shielded cable and ground at the other end of the shield. I will try to attach drawings.

Many Radios of this vintage had this feature as several manufacturers (RCA in particular) offered "Phono Adaptors" for radios. These Phonos had no Audio Amplifiers, as the Radio was to be used for this. The proposed TV sets between 1939 and the end of consumer electronic production due to WWII also used the radio as an audio amplifier. RCA sold a kit (Type 240X1)to add the above switch to the back of the cabinet. All of this legitimizes this modification, assuming this is done with period parts.

My Philco 41-255 did something different. they advertised "FM and TV sound the Wireless Way" Ther is a pushbutton on the presets for "TV FM Phono" I do not know the frequencies used, but each of these required a built in "Wireless Oscillator".

Direct connection always produces better sound than using a transmitter, no matter how good the transmitter is.

Best Regards,
John, MrFixr55

"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis

Best Regards, 

MrFixr55


Messages In This Thread
40-155T Add Aux Input Questions - by tgr131 - 03-18-2022, 11:15 AM
RE: 40-155T Add Aux Input Questions - by Mondial - 03-18-2022, 03:28 PM
RE: 40-155T Add Aux Input Questions - by tgr131 - 03-18-2022, 03:36 PM
RE: 40-155T Add Aux Input Questions - by Mondial - 03-18-2022, 03:46 PM
RE: 40-155T Add Aux Input Questions - by tgr131 - 03-18-2022, 05:32 PM
RE: 40-155T Add Aux Input Questions - by MrFixr55 - 03-19-2022, 09:22 AM
RE: 40-155T Add Aux Input Questions - by tgr131 - 03-19-2022, 09:46 AM
RE: 40-155T Add Aux Input Questions - by tgr131 - 03-19-2022, 11:34 AM



Users browsing this thread: 3 Guest(s)
[-]
Recent Posts
The list of my radio & TV collection!
Hi Richard. Yes, we are waiting for warm weather. I have more than a dozen hulls waiting to be painted.RadioSvit — 11:06 AM
6TPZ and 5TPO Radio Help
Then it is even easier. Yep, my GE guide also says "Silicon".morzh — 09:43 AM
462ron
Mike, according to my ECG replacement guide, the AR107 & AR108 both cross reference to a ECG 123A as does a GE-10. T...462ron — 09:41 AM
Atwater-Kent 84, restoration.
The 66 Ohm filter in the 1st detector's plate circuit. Look in the early version sch. Here it is, the spiral that ma...morzh — 09:11 AM
6TPZ and 5TPO Radio Help
Ron yes, that was found. The problem is trying to find GE-10 for AR107/108. I could not find even mentioning of it. ...morzh — 09:06 AM
462ron
Your output transistor X6 cross references to a GE-3 transistor and I’ve used that before. There are a few here on eBay…...462ron — 07:58 AM
Atwater-Kent 84, restoration.
Mike; Where was this RF choke located? I remember seeing on a few sets that had detector-amplifiers ahead of the powe...Arran — 02:29 AM
6TPZ and 5TPO Radio Help
Thank you very much. I'll let you know how it goes.R3Sons — 11:00 PM
Atwater-Kent 84, restoration.
Hello mike, Nice job hopefully it works and I am sure it will. Sincerely Richardradiorich — 09:15 PM
The list of my radio & TV collection!
Hello Peter, I am glad you got the radios and I too have that same zenith in my collection ! I am also waiting for the...radiorich — 08:52 PM

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

>