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Post by KneeBiter on Apr 9, 2012 23:00:27 GMT -5
Hello all. New on this board. Long time Browning user just getting back into it.
Picked up a nice clean MK iv. has the 99 mod. everything works good except that the receiver has nothing on ssb. Am receives great but when switched to ssb it is dead.
I took the bottom cover off and noticed a brown wire hanging loose. Not sure if it was disconnected for the mod or if it fell off the switch somewhere.
Anyone have a MKiv that they could post a nice pic of the underside of the receiver so maybe I can see if this wire should be hooked up? Or any other suggestions? thanks
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40sx
Mudduck
Posts: 39
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Post by 40sx on Apr 10, 2012 6:21:29 GMT -5
Since you already have yours apart, it may be easier for you to post a picture of yours. Without bending the detached wire, try to photograph where it comes from and to what part of the radio you believe it goes.
Dennis
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Post by KneeBiter on Apr 10, 2012 15:37:58 GMT -5
Thank you for the reply. Here are some pics. Again, everything works but when you switch the receiver to SSB either lsb or usb it has nothing. Attachments:
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Post by KneeBiter on Apr 10, 2012 15:39:45 GMT -5
another Attachments:
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Post by KneeBiter on Apr 10, 2012 15:40:42 GMT -5
other end Attachments:
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Post by KneeBiter on Apr 10, 2012 15:43:14 GMT -5
Top side Attachments:
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Post by KneeBiter on Apr 10, 2012 15:44:37 GMT -5
Not even sure this wire is the problem but it is a start. I know the ssb on these radios are not stable but I would really like it to work as should. Any help is appreciated.
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Post by FIXR on Apr 11, 2012 16:14:30 GMT -5
Knee,
The only brown wire that I'm familiar with in that area runs from the ground foil of the oscillator/mixer board to a lug on the tuning (band) switch.
Alan
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Post by KneeBiter on Apr 11, 2012 17:06:56 GMT -5
Alan,
Thanks for the reply. Now to find out which lug?? Anyone with a MK4 Willing to remove the bottom cover on the receiver and take some pics?
Thanks again
KNEE
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40sx
Mudduck
Posts: 39
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Post by 40sx on Apr 12, 2012 5:53:42 GMT -5
Knee, can you feel around the lugs for a stub of wire where the brown wire might have broken off. Also look carefully at the band switch lugs for any signs of a broken wire.
Dennis
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Post by KneeBiter on Apr 12, 2012 6:06:47 GMT -5
Will try that when I get home from work. Thanks
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Post by KneeBiter on Apr 15, 2012 23:57:25 GMT -5
Checked it out today. Found that the brown wire was cut from the xtl switch when the mod was done so not my problem.
I am taking a stab and thinking that c225 might be bad, It is dark on the top like it has been heated up. 68pf dipped mica. It is in the v204 circuit which controls the ssb.
Also I found that when in ssb mode I do still receive but it is low and garbled and cannot tune it in. Anyone that has a schematic that is tech savvy have any thoughts on my hunch?
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Post by cbrown on Apr 16, 2012 8:24:54 GMT -5
Try pulling out the AGC and see if that improves your SSB receive.
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Post by KneeBiter on Apr 16, 2012 13:45:47 GMT -5
replaced cap and same thing. agc does not help on ssb  |
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Post by 2600 on Apr 23, 2012 23:14:03 GMT -5
Are you sure the 6BE6 tube is good? They seem to go bad even if the radio is never used for sideband.
We have seen more than a few bad trimmer caps in the SSB receive. They become an open circuit and cause the oscillator circuit on the 6BE6 to quit. Not an easy component to test. You can put a 20 or 30 pf disc capacitor in parallel with one of them and see if you start hearing signals that way. No way that a fixed cap will be on frequency, but it could confirm that the trimmer cap is bad. The shaft inside that trimmer makes contact with the bushing that holds it in place. The silver plating becomes tarnished and breaks the metal-to-metal contact between the shaft and bushing, causing the trimmer cap to become an open circuit.
73
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Post by KneeBiter on May 17, 2012 0:05:57 GMT -5
Sorry it took so long to reply. have not been into the radios for some years. So even though I know enough to trace the schematic and take advice from you guys I decided to take it to a local tech that is up on these radios on a regular basis. Sure enough the trimmers were bad. He replaced both of them and while he had it did a few other things. Thank you for all the help and suggestions. I will try and find another one for me to fool with and get my brain back to where it once was.
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Post by cbrown on May 17, 2012 8:29:10 GMT -5
Glad you got it sorted.
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