    
Ou812
New member
Username: Ou812
Post Number: 8
Registered: 11-2006
| | Posted on Friday, February 23, 2007 - 1:36 am: | 
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I have a Mckinley with weak transmit and no or weak modulation. (Self inflicted).
This radio I got used and although it was beat up it worked real well. A year ago I cut R104 for the mod then started peaking the coils L26,L27,L28,L29 when I came up on L36 something snapped and it lost carrier.
TX light goes red when keyed.Swapped mics no change.PA speaker works fine with Audio applied.
I recently installed a new Sylvania ECG235 and NTE236.
IC5 MB3756 previously tested with no voltage at pin 8 but now seems fine with 8.2 on tx?
Still showed nothing on meter.
I am using the SAMS for a Cobra 142/140 GTL Uniden Board TJE-016V-1.
TP8 will not drop below 56mA and
TP7 barely gets down to 35mA.
Tuning VR6,VR7,VR8,VR9 and the L's I have 3 watts out and no Mod on AM.
External Watt meter AM shows about 3 watts.
External Mod meter will fully calibrate but no swing on AM.
External SWR will fully calibrate and reflects about 1.5:1
USB and LSB will swing about 1/2 watt on Palomar PW-5000 (0-30 scale) and shows modulation to about 40-50 percent.
SWR meter will go forward slightly with mod applied on USB / LSB.
I am going to replace the IC4 TA 7222P as it PIN #9 shows 2.9v on Rx and 2.6v on Tx but I have read on this forum simular probs with bad caps will blow out the chip again. What caps should be replaced as well?
Ordered NTE1278 and C118 470uf 25v cap.
Thanx for all your help...much appreciated. |
