Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
Collins R-390 Receiver RX problems




 
The AM Forum
September 20, 2018, 01:14:39 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Collins R-390 Receiver RX problems  (Read 762 times)
0 Members and 1 Guest are viewing this topic.
WB4YVO
Member

Offline Offline

Posts: 52


« on: August 16, 2018, 11:27:01 PM »

All, Have been using this for many years  It was working perfect yesterday. I turned it on today and NO Receive at all.. All bands The Calibrator doesn't work either.. So Receiver is completely deaf..It does make noise and all functions seem to work  Just NO signals.. Antenna is Good it works on my other R-390A receiver..

Where do I start looking? What could happen as it sat overnight NOT On..

Its mounted in a rack with my R390A.. Its very heavy I will have to pull it and put on bench..

Help Any 390 experts out there??

Skip

Logged
KL7OF
Member

Offline Offline

Posts: 2021



« Reply #1 on: August 17, 2018, 09:38:54 AM »

Start with the AC cord, then the fuse , then the switch on the front panel. ( before you pull the RX)  Good Luck...Steve
Logged
PA0NVD
Member

Offline Offline

Posts: 285


Nico and Chappie (Chappie is the dog...)


« Reply #2 on: August 17, 2018, 11:35:57 AM »

When it makes noise, the receiver including the IF seems ok. When it does not receive, my guess is that the oscillator for the first mixer doesn't work.
Logged
KA3EKH
Member

Offline Offline

Posts: 436



WWW
« Reply #3 on: August 17, 2018, 01:26:49 PM »

The 3TF7 or whatever that stupid ballest tube is on the front of the IF amplifier section is always suspect. When that tube opens the there is no filament for the PTO and crystal oscillator deck so you get just what you describe. Noise but no signals. You can replace the tube with a resistor or zeniur diode although I forget the exact values. Don’t need filament regulation in normal use anyway.

Logged
WD8KDG
Member

Offline Offline

Posts: 233



« Reply #4 on: August 17, 2018, 08:13:16 PM »

All, Have been using this for many years  It was working perfect yesterday. I turned it on today and NO Receive at all.. All bands The Calibrator doesn't work either.. So Receiver is completely deaf..It does make noise and all functions seem to work  Just NO signals.. Antenna is Good it works on my other R-390A receiver..

Where do I start looking? What could happen as it sat overnight NOT On..

Its mounted in a rack with my R390A.. Its very heavy I will have to pull it and put on bench..

Help Any 390 experts out there??

Skip



Just to clarify...……..is the question pertaining to a R-390 or a R-390/A??

Regards,
Craig

Logged

Ham radio is now like the surprise in a box of "Cracker-Jacks". There is a new source of RFI every day.
WB4YVO
Member

Offline Offline

Posts: 52


« Reply #5 on: August 17, 2018, 11:55:43 PM »

R-390

Skip
Logged
w3jn
Johnny Novice
Administrator
Member

Offline Offline

Posts: 4572



« Reply #6 on: August 18, 2018, 06:29:02 AM »

Either way, it's most likely the 3TF7.  See if it's hot - if not, it's a gonner. 

Easy workaround - replace the BFO and PTO tubes with 12BA6s and short across the appropriate pins of the 3TF7.  The reason for the 3TF7 was to supposedly regulate the oscillator current.  Great idea in 1951 taking into account possibly mobile environments on generators with fluctuating voltage - but completely unnecessary today.
Logged

FCC:  "The record is devoid of a demonstrated nexus between Morse code proficiency and on-the-air conduct."
WB4YVO
Member

Offline Offline

Posts: 52


« Reply #7 on: August 19, 2018, 11:40:55 AM »

OK, All Found problem  My RF tube ( 6AJ5) was bad.. I did not have one so substituted a 6AK5.. radio now works again.. Will have to order some 6AJ5 tubes..

I was looking at the wrong tubes first in the IF chain.. Then realized I was not looking at the RF chain  So first tube I replaced worked 1St RF Amp V201

Skip

Logged
PA0NVD
Member

Offline Offline

Posts: 285


Nico and Chappie (Chappie is the dog...)


« Reply #8 on: August 19, 2018, 05:10:46 PM »

6AJ5 = 6F35
Fine that it works, the 6AK5 has twice the transconductance.
Logged
WB4YVO
Member

Offline Offline

Posts: 52


« Reply #9 on: August 19, 2018, 10:47:36 PM »

Well, I have ordered the right tube.. But at lease I know what the problem was..

Skip

Logged
WB4YVO
Member

Offline Offline

Posts: 52


« Reply #10 on: September 10, 2018, 09:30:11 PM »

Does anyone have a parts layout underside of the R390  IF Chassis?

Skip
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.038 seconds with 18 queries.