| Author |
Message |
    
Xlaxx
Intermediate Member
Username: Xlaxx
Post Number: 301
Registered: 4-2002
| | Posted on Sunday, January 27, 2008 - 11:10 pm: | 
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I recently acquired an older, very clean Uniden PC76XL.
The receive is very poor,... way to Low and I can barely hear it, but it does receive as I can hear stations (that should be much stronger). All the knobs are functional, squelch is open (min), RF Gain is open (max). I tuned into Ch.6 (Super Bowl) and it really should have been much louder (IMHO). Hardly any needle deflection, but it does work. It should have been slamming over to the right!
I have a resonant antenna and wattmeter in line and the mic is working. The radio shows excellent power output.
What am I missing here? and how can I get the radio ears working properly again?
Thanks for the help!
XLAXX |
Xlaxx
Intermediate Member
Username: Xlaxx
Post Number: 302
Registered: 4-2002
| | Posted on Monday, January 28, 2008 - 2:11 pm: |
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I can hear no noise floor or static,... only really strong signals.
XLAXX |
Tech858
Moderator
Username: Tech858
Post Number: 111
Registered: 10-2007
| | Posted on Monday, January 28, 2008 - 3:53 pm: |
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Xlaxx
Check the RF gain transistor , it is shown as TR7 in the schematic I have , sounds like it has gone snaffoo .
Tech858/Jim
MM0TXO
CEF#858
HAM#230
CVC#116
Wavin' a hand at ya' fae Scotland 
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Kabar
Member
Username: Kabar
Post Number: 56
Registered: 6-2003
| | Posted on Tuesday, January 29, 2008 - 5:24 am: |
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Look in the front of the radio and find VR1 and turn it up and see if this helps.
If this is turned down you should hear the white noise increase as you turn it up.
Hope this helps. |
Xlaxx
Intermediate Member
Username: Xlaxx
Post Number: 303
Registered: 4-2002
| | Posted on Tuesday, January 29, 2008 - 9:57 am: |
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Tech858 and Kabar-
Thanks for the replies.
I will try both of your recommendations.
I have no service manual.
I had one of these a few years ago and it was pretty dirty so I sold it,... my loss! Found this one on Sunday, it is very clean, just needs some TLC.
I did note that D11 was already snipped,...
DK shows 6W swing 35W Bird PEP. Not bad,... just need to get the receive back.
Will let you know something tonight.
Thanks
XLAXX |
Xlaxx
Intermediate Member
Username: Xlaxx
Post Number: 304
Registered: 4-2002
| | Posted on Tuesday, January 29, 2008 - 12:43 pm: |
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Still a little bit on the quiet side. I sprayed some Deoxit into VR7 and VR1 and worked them some. VR1 brought it up some,... any other thoughts?
XLAXX |
Xlaxx
Intermediate Member
Username: Xlaxx
Post Number: 305
Registered: 4-2002
| | Posted on Tuesday, January 29, 2008 - 1:32 pm: |
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Messed with VR1,... brought it up some (just a little bit). VR3 (squelch) did virtually nothing. Some improvement if I turn off the ANL/NB, but when I turned it on,... it quiets everything down again,... too much for my liking.
Adjusted VR2 for meter deflection,... did nothing to the needle movement either. Radio receives, but should be MUCH MUCH stronger.
Anything else I can do?
TNX
XLAXX |
Tech858
Moderator
Username: Tech858
Post Number: 114
Registered: 10-2007
| | Posted on Tuesday, January 29, 2008 - 8:36 pm: |
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Try replacing TR7 with either a new 2sc1674L or try a 2sc2999 transistor .
Tech858/Jim
MM0TXO
CEF#858
HAM#230
CVC#116
Wavin' a hand at ya' fae Scotland
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Scarecrow
New member
Username: Scarecrow
Post Number: 1
Registered: 1-2021
| | Posted on Tuesday, February 09, 2021 - 9:22 pm: |
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Hey. First time Poster
Have the same radio with the same issue, turned up the VR1 and got a big improvement.
Thx for the thread |
Raya
Junior Member
Username: Raya
Post Number: 43
Registered: 6-2017
| | Posted on Thursday, February 11, 2021 - 9:16 am: |
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axx:
First thing from your description is that the problem is that the problem may be much bigger than you alone (myself included) can handle ourselves. Bring the radio to a "GOOD" qualified tech and have them do the repairs aka better receiving.
AND while you are there ask them to change all the electrolytic caps to new caps aka a Cap Job.
And and lastly request that they align the radio to exact factory specs as the radio came off the factory assembly line.
PLEASE DO NOT jack up the power from the radio or the modulation beyond factory specs. If you want more power just buy an external amplifier.
As an amateur operator I on the personal level do not suggest running illegal power. As an amateur I can assure you that I get much much more enjoyment from a contact using the lesser power levels. It is a challenge. |
