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: 2 Guest(s)
[-]
Recent Posts
trying to identify this wire type
The red wire is rubber covered wire. The others are cotton braid over rubber often in colors or a tracer, also strand...Chas — 02:43 PM
trying to identify this wire type
Greetings Phorum members, Hope you can help me identify this type of wire in the photo I have attached.  I am not sure ...georgetownjohn — 01:53 PM
Philco 60 Squealing
All correct shields must be in place, all tubes correct no subs of any kind. Check any soldered, riveted ground conne...Chas — 01:24 PM
Philco 60 Squealing
I have recapped and replaced out of tolerance resistors and so on. Radio plays nicely on fairly strong stations. The pro...dconant — 10:55 AM
Philco 46-420 Code 121 Reception issues
Welcome Eric, I agree with Bob and far as the two main electrolytic filter capacitors did you change them yourself or w...radiorich — 11:43 PM
Philco 46-420 Code 121 Reception issues
You mentioned the Philco manual and going through the check points...just to be sure we're on the same page here's the m...klondike98 — 08:13 PM
Philco 42-1008 conversion kit
Interesting. I haven't seen that before.klondike98 — 07:02 PM
12' Philco
Yes I had looked for it on the web as well some time back and could not find it. I was glad to see it turned up in Ron'...klondike98 — 06:59 PM
Shadow Meter Bulb
Now if you had a set with a tuning light then the bulb type is important to the circuit, some sets used those prior to t...Arran — 04:58 PM
Shadow Meter Bulb
Ok. Thanks for the correction.RossH — 03:09 PM

[-]
Who's Online
There are currently 4515 online users. [Complete List]
» 1 Member(s) | 4514 Guest(s)
Avatar

>