06-24-2023, 09:57 PM
Hi Jordan,
Is there a switch with the phono connection? Is it an "RCA Jack?"
If you can, post a pic of the jack and the underside of the chassis. Although Philco did not put phono or "phono - television" jacks on this radio, it was not uncommon to have a Radio Shop install one back in the day, either from a kit (RCA sold a neat one) or individual parts. Some had a switch, some relied on the user to tune the radio to a dead section of the band.
+1 on Morzh's comments. The phono input is usually isolated from any voltage by a capacitor of approximately 0.1uF. Sometimes, this is added, but most of the time, the mod uses the cap between the center (wiper terminal) for the volume control and the grid of the first audio tube (a 6Q7 in your case).
In troubleshooting radios, if it has a phono jack, I will use it to inject an audio signal from the computer, a CD or MP3 Player, etc. If the phono connection is the RCA type yu can get a 3.5mm TRS to twin RCA adapter cable) It would have 2 RCA plugs because the MP3 / computer / CD Player is stereo. For teting purposes, you can use just 1 of the 2 RCA plugs. You will be missing a channel but it willbe good for testing.
'If you can't get good, clear, loud audio from using the phone jack to inject a signal, then you have a problem with the 1st Audio or "Power Amp" circuits. Alignment will not solve this. The Audio circuit is relatively simple.
Was the short wave station nice and loud or barely heard? Are you in the basement? How is AM reception on another radio in the same location? Are you urban, suburban or rural? This is a common, transformer powered version of the "All American Five" 5 tube radio circuit. The AA5 term usually applies to transformerless sets whose B+ is usually in the order of 100V. These sets do perform rather well. The same style tubes with 200 -250V Plate circuits perform even better.
I practically cannot run an AM radio in my house (what with all of the computer, LCD, WiFi, LED lights, etc., unless it has a "ferrite stick" type antenna. Somehow, ferrite stick antennas seem to be less susceptible to RFI. (Radio Frequency Interference). Try turning off ALL computers and monitors, cable modems, unplug all LCD TVs, turn off all LED and Fluorescent lights. Also, try to use a longer wire, say 50 Ft, run from the house to a tree, "pointing" to the direction of the stations.
I live in suburban NY, served by at least 5 Clear channel 50KW stations, and many others. In the past 10 years, it has become almost impossible to listen to AM, even in any of our 3 cars.
One trick would be to touch the antenna wire directly to the metal "grid cap" on top of the 6A8 tube and try to tune broadcast stations. If you pick up more stations than when the antenna is connected to the correct terminal, then there is an issue with either the Antenna coil or the band switch.
Hope this all helps. Keep on trying and you will succeed. Keep on posting and we will help. When you get this one working, find another and fix it! For a non-antique radio hobbyist, you have done really well so far!
Best regards,
MrFixr55
Is there a switch with the phono connection? Is it an "RCA Jack?"
If you can, post a pic of the jack and the underside of the chassis. Although Philco did not put phono or "phono - television" jacks on this radio, it was not uncommon to have a Radio Shop install one back in the day, either from a kit (RCA sold a neat one) or individual parts. Some had a switch, some relied on the user to tune the radio to a dead section of the band.
+1 on Morzh's comments. The phono input is usually isolated from any voltage by a capacitor of approximately 0.1uF. Sometimes, this is added, but most of the time, the mod uses the cap between the center (wiper terminal) for the volume control and the grid of the first audio tube (a 6Q7 in your case).
In troubleshooting radios, if it has a phono jack, I will use it to inject an audio signal from the computer, a CD or MP3 Player, etc. If the phono connection is the RCA type yu can get a 3.5mm TRS to twin RCA adapter cable) It would have 2 RCA plugs because the MP3 / computer / CD Player is stereo. For teting purposes, you can use just 1 of the 2 RCA plugs. You will be missing a channel but it willbe good for testing.
'If you can't get good, clear, loud audio from using the phone jack to inject a signal, then you have a problem with the 1st Audio or "Power Amp" circuits. Alignment will not solve this. The Audio circuit is relatively simple.
Was the short wave station nice and loud or barely heard? Are you in the basement? How is AM reception on another radio in the same location? Are you urban, suburban or rural? This is a common, transformer powered version of the "All American Five" 5 tube radio circuit. The AA5 term usually applies to transformerless sets whose B+ is usually in the order of 100V. These sets do perform rather well. The same style tubes with 200 -250V Plate circuits perform even better.
I practically cannot run an AM radio in my house (what with all of the computer, LCD, WiFi, LED lights, etc., unless it has a "ferrite stick" type antenna. Somehow, ferrite stick antennas seem to be less susceptible to RFI. (Radio Frequency Interference). Try turning off ALL computers and monitors, cable modems, unplug all LCD TVs, turn off all LED and Fluorescent lights. Also, try to use a longer wire, say 50 Ft, run from the house to a tree, "pointing" to the direction of the stations.
I live in suburban NY, served by at least 5 Clear channel 50KW stations, and many others. In the past 10 years, it has become almost impossible to listen to AM, even in any of our 3 cars.
One trick would be to touch the antenna wire directly to the metal "grid cap" on top of the 6A8 tube and try to tune broadcast stations. If you pick up more stations than when the antenna is connected to the correct terminal, then there is an issue with either the Antenna coil or the band switch.
Hope this all helps. Keep on trying and you will succeed. Keep on posting and we will help. When you get this one working, find another and fix it! For a non-antique radio hobbyist, you have done really well so far!
Best regards,
MrFixr55
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
MrFixr55