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 85T ??
#1

I have an RCA 85T, I'v recapped all the paper Caps, I used 10 Mfd Electrol. for C 18 C19 and C20 (was 8, 5, and 5) No static but when I tune 89 and higher on the dial the volume drops considerabilly. All stations track there place on the dial. do i have an A.V.C. problem ? or something else ? can any one steer me in the correct direction ?
b.t.w. I replaced the power Transformer, it was leaking wax.
Thank you for any and all help !
Jack
#2

Check your alignment instructions and see if there is an adjustment for the high-end of the band.
#3

Looking at the schematic, looks like this would be C1.
#4

Also check your 6A7 tube. I've seen too many recently with the weak pentode section, and in this radio where it is both mix/osc and 1st RF it may be critical.
The tube should be at least 800 (the chart gives 1000) on the pentode and above 150 on the osc.
#5

Thanks TA, morzh's
I touched up the Alignment(C1, C5) it helped somewhat.
I will get another 6A7 to try.
Thanks again Both of you

Jack
#6

Jack

Make sure you DO know your 6A7 is good.
I had weird experience with them just a month ago (I needed to check the theory that my 6A7 was not oscillating properly below 6MHz, my FB band did not work there at all) where I bought an NOS tube from a guy (and he was an honest guy) and it tested about 600 instead of 1000, which is "?" territory. I was able to prove the theory (the oscillator worked as it should) but the tube was weak. That was #1.
Then I bought another NOS tube from another guy and it was near-dead, at 300. The guy admitted he did not test the tube as his tester does not test them, and sent me another RCA NOS one and that one was just fine (that's the one I keep in the radio). That was #2.
But before this guy had a chance to react I bought the third tube, also NOS and this time the guy claimed he tested it and it was like 150% or so (not sure what that means).
The tube came, and again, the pentode section was extremely weak. I suspect he tested only the oscillation section (in all three tubes it was indeed very strong).

So, out of four tubes and from three sellers only one was testing properly.
So make sure you buy from someone who tested it on a mutual conductance tester that tests both parts, the oscillator and the pentode, and both are close to new value or at least show strong "good". Ask the seller about how he tested them.
Or go to one of the sources folks here recommend (Bob Dobush at findatube.com).




Users browsing this thread:
[-]
Recent Posts
48-482 rear panel help
Hi Kettlechip and welcom to the Phorum. The back panel question is interesting. I have quite a few radios that use pow...MrFixr55 — 08:24 AM
Philco 46-480 Electronic Restoration
Not too much at all! :lol:  Sounds like you’re just dabbling into the hobby!jrblasde — 07:56 AM
Philco 46-480 Electronic Restoration
Hi Joseph, Fortunately, Ms. Fixr does not read my computer, or she would warn you against coming to me for sanity ch...MrFixr55 — 07:27 AM
48-482 rear panel help
There's a picture of one of the plastic covers in the following thread: I bought a full set of them in 2012 or so fro...klondike98 — 11:15 PM
Philco 46-480 Electronic Restoration
Good sanity check! You are correct—the first (as in, the most counterclockwise) position is for the push button presets....jrblasde — 11:05 PM
Philco 46-480 Electronic Restoration
Hi Joseph, First, verify that your band selector is in the correct position for what you want to do. I believe tha...MrFixr55 — 10:59 PM
Philco 46-480 Electronic Restoration
Got my replacement signal generator in the mail today! I was able to finish alignment of the IF section. I’ve got some t...jrblasde — 09:58 PM
The list of my radio & TV collection!
EdHolland. Glad you liked it. Thanks for the supportRadioSvit — 05:24 PM
The list of my radio & TV collection!
Great stuff, Peter thank you for posting.EdHolland — 04:06 PM
My Philco 37-116 Restore
The crack goes from almost the bottom of the tube to well past the fat part. It is an ST type tube. The filament is open...dconant — 10:04 AM

[-]
Who's Online
There are currently 284 online users. [Complete List]
» 2 Member(s) | 282 Guest(s)
AvatarAvatar

>