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

RCA 8X71-Hum
#1

I've got a strange one. All electrolytic and wax caps replaced. Resistors replaced as necessary. Tubes tested. Set aligned on both AM and FM.
The problem is that I get a hum on AM only and only when on a station. In between stations on AM is silent as well as FM.
Any thoughts?

Thanks,
Eric
Schematic:
http://www.nostalgiaair.org/Resources/251/M0015251.htm

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org

#2

Selective hum like this is usually environmental. Try moving the radio to a different area of the house and see if it goes away. My workbench is insane for reception problems. There's some kind of field there that creates a ton of RFI, but if I move the radio under test off of the bench, even just a couple feet, all the noise goes away. Before I discovered this, it nearly drove me mad trying to figure out what was wrong with the radios. Icon_smile
#3

Agree, try moving set around. Most likely a really old dimmer, imported unshielded power supply, shut your bench down completely first.
#4

Thanks BrendaAnnD, out of the basement and away from my bench the hum is minimized. It's just strange that this is the only radio that I've had this issue with.

Eric
The Villages, FL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org





Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
The list of my radio & TV collection!
Ok. Everything opens with a direct link. Yes. As Arran said, this is a transistor radio. It is a more expensive version ...RadioSvit — 03:07 PM
Electrolytic restuffing/internals
Gary I thought the same, but then isn't a hacksaw by definition is the one with fine teeth? >>A hacksaw is a...morzh — 03:01 PM
The list of my radio & TV collection!
Ah a KiJiJi seller! I've noticed that KiJiJi tends to be where all of the rejects from craigslist go, not that there ...Arran — 01:43 PM
Electrolytic restuffing/internals
When I'm lazy, I use a razor knife with a new blade. Nice smooth, even cut, minimal loss of material and no trimming or ...RodB — 01:39 PM
Electrolytic restuffing/internals
I still disagree with your sawing or cutting method. It is much easier in terms of the opening method and better in term...Vlad95 — 01:29 PM
Electrolytic restuffing/internals
For the question about the jagged hacksaw cut, the most common reason is too aggressive 'bite' of the saw blade. I use ...GarySP — 01:26 PM
Electrolytic restuffing/internals
Well I retire in about three years. My plan is to build a better workshop that has an area for these kinds of things. ...bridkarl — 01:14 PM
Electrolytic restuffing/internals
Ido remember you telling us about your health condition. Yes, a vise is a good thing to have. Many things I do I woul...morzh — 01:08 PM
The list of my radio & TV collection!
Strange, the second link works for me without problems. Try this direct link. Or try searching for "AKKORD DELUX ...Vlad95 — 01:08 PM
The list of my radio & TV collection!
Looks like Peter and I have the same idea.RodB — 11:37 AM

[-]
Who's Online
There are currently 811 online users. [Complete List]
» 1 Member(s) | 810 Guest(s)
Avatar

>