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: 1 Guest(s)
[-]
Recent Posts
Philco Model 249 made in England
Gary - Thanks for responding!  I hadn't actually taken possession of it at the time of my post but since you said it was...fklown — 03:32 PM
Philco model 40-100
Marion; Replacing volume controls was something some service shops did in years gone by to make a little extra profit...Arran — 03:24 PM
Philco Model 249 made in England
Welcome to the Phorum, fklown!  That's one heck of a Philco 'yardstick' you've got there!  Could you possibly post a clo...GarySP — 03:19 PM
Philco model 40-100
Arran, Thank you so much for your assistance and the link to the fleabay listing! They say a picture is worth a thousan...mhamby — 01:43 PM
Philco Model 249 made in England
I wonder if anyone has any information or experience with this model.  My internet searches are coming up with nothing. ...fklown — 11:40 AM
Road Trip for a Philco 46-480
Good morning, folks! I’ve finished the cabinet and the electrical restoration, and have detailed those in their respecti...jrblasde — 10:56 AM
Studebaker/Philco AC-2687 car radio
Arran, Thanks for checking you manuals. I appreciate that. Let me know what you find. PhilPdouglaski — 08:46 AM
Studebaker/Philco AC-2687 car radio
I have some car radio service manuals, Riders I think (not to be confused with the big blue binders), so I may see if on...Arran — 01:20 AM
Philco model 40-100
Greetings; Here is an update, I found a listing on fleabay for a similar chassis to yours, and it has a photo of what...Arran — 12:58 AM
Philco model 40-100
Greetings; I think I may have found a clue as to what is missing, from a search I made, there is a rear view of the c...Arran — 12:12 AM

[-]
Who's Online
There are currently 762 online users. [Complete List]
» 3 Member(s) | 759 Guest(s)
AvatarAvatarAvatar

>