-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Connex 3300 rx help needed
- Thread starter Mk121
- Start date
Yeah, just a simple "continuity check" from center to board where pigtail is soldered can go a long way in solving this...
Another thing though too, check for any re-work in areas it shouldn't have any. For they can take any signal going into the radio thru the SO-239 - and put it straight to ground and you can get results like this.
So examine the board and foil trace connections - even the Cap that is the RF decoupling for the Antenna can be suspect as being bad.
So pay attention to layout and look for any shorts from loose hardware or poor soldering causing shorts...
Another thing though too, check for any re-work in areas it shouldn't have any. For they can take any signal going into the radio thru the SO-239 - and put it straight to ground and you can get results like this.
So examine the board and foil trace connections - even the Cap that is the RF decoupling for the Antenna can be suspect as being bad.
So pay attention to layout and look for any shorts from loose hardware or poor soldering causing shorts...
Last edited:
Thanks for the help so far everyone. Andy what do you mean when you say check continuity from center to board?
I did like you said and reflowed the two mounting tabs in the back, no difference. Also reflowed the area that the antenna wire goes into the board. Next on my list is to definitely check out c158 and c159. I didn't know about a decoupling cap. Does it have a board number? Is it a ceramic disc type? I should get some time tonight to tinker with it again.
I did like you said and reflowed the two mounting tabs in the back, no difference. Also reflowed the area that the antenna wire goes into the board. Next on my list is to definitely check out c158 and c159. I didn't know about a decoupling cap. Does it have a board number? Is it a ceramic disc type? I should get some time tonight to tinker with it again.
From Center of where your coax center goes, into the SO-239 (the PL-259 male part goes there) to where it mounts to the board - as shown on pics.
You may also - per the schematic, do the same continuity check from L31 and L51 meet - thru that jumper from the SO-239 follow back to C43 - one leg shows short, other one won't - it's a cap - keeps DC voltages out but let's RF thru. The J29 should take you back to where L6 area is...
It's why I mentioned the "19mm Wrench" because the SO-239 - center lead pass thru to the inside flange - may be broken or the wire from it to the board may have broken - reflow solder at that connection too - from the wire to that "stud" to see if you can re-establish the pass thru connection to the jumper going to the board...
You may also - per the schematic, do the same continuity check from L31 and L51 meet - thru that jumper from the SO-239 follow back to C43 - one leg shows short, other one won't - it's a cap - keeps DC voltages out but let's RF thru. The J29 should take you back to where L6 area is...
It's why I mentioned the "19mm Wrench" because the SO-239 - center lead pass thru to the inside flange - may be broken or the wire from it to the board may have broken - reflow solder at that connection too - from the wire to that "stud" to see if you can re-establish the pass thru connection to the jumper going to the board...
Last edited:
Well I got a little bit of time and figured I would try fooling with my scope again to try and show you guys what I'm seeing. Please tell if these pictures look right. First picture is what I'm getting when I probe antenna jumper, so-239 and everything in between up to tr17. Second picture is what I'm getting at tr18.
It seems like we have moved on to the coax connector and forgotten that he still has incorrect voltages on IC1?
is that right or did i miss something?
MK121, did you ever figure out where the missing 8 volts was?
LC
is that right or did i miss something?
MK121, did you ever figure out where the missing 8 volts was?
LC
I through the dmm on the radio before I left for work and looks like I have about 9 volts on pin 11. Just looked at the schematic quick and I believe I'm reading the pins in the right order. Pin 1 would be top left with radio flipped over. Going to check all pins later today and report back my readings.
Well, some questions came up, so we have to make sure the signal, if any can be sent thru - is making it. Else no matter what - Signal or Not, we wouldn't know if the pipeline to the section even worked - due to the passage of TR18 - we would not again know if it was a body capacitance coupling issue or a simple antenna leaking into the system...
If it were me, Id' simply remove TR17 and set the probe to the Base lead and observe the input and peak L6 - to even see if the signal can be peaked thru tuning - for this can be from a range of poor signal degradation issues...
We addressed (hopefully) any attenuation issues for tone from the Antenna Jack to the RF amp section...
Only Id like to know if the "tone" is set for the 27MHz band somewhere?
We addressed (hopefully) any attenuation issues for tone from the Antenna Jack to the RF amp section...
Only Id like to know if the "tone" is set for the 27MHz band somewhere?
The issue with the chassis SO239 was brought to my attention based on MK's description of what was happening. IC10 would have nothing to do with it. MK's scope should be able to see a signal along the entire path right up to L6 with no power applied to the radio and for good measure unsolder D15 & D16 if he can't get his equipment to show all along that path then there must be other issues either with the test equipment or the path in the radio that is interrupted by shorts or opens in that path. Once that issue is resolved then IC1 can be tackled if indeed there is an issue there. I will say that it would only take a minute or less to check the voltages in IC1 but even if you removed IC1 it still would have no effect on not having a signal going into L6 especially with D16's and 15's one leg unsoldered. And I am now taking my toys and going home.
OldTech
My signal generator is set at 27.205 with 1000hz tone. What do you think about the scope signals in the pics?
I did go through and resolder the antenna jumper wire and replaced c158 just to make sure that was all good.
I'm not sure what you mean with remove tr17. If I remove it how can I look at the input on it's base? I know L6 is a unshielded tuning pot but what exactly is it for? I did try to tune L7 and L8 and could hear the tone go up and down when I had the center pin making contact. L6 made no difference in sound when turning it up or down.
I did go through and resolder the antenna jumper wire and replaced c158 just to make sure that was all good.
I'm not sure what you mean with remove tr17. If I remove it how can I look at the input on it's base? I know L6 is a unshielded tuning pot but what exactly is it for? I did try to tune L7 and L8 and could hear the tone go up and down when I had the center pin making contact. L6 made no difference in sound when turning it up or down.
As I stated before you should be able to measure a signal from the antenna terminal to the base of TR17 and TR17 does not need to be there to see a signal at the point on the board where TR17's base would be. Actually, if you have good eyes and can unsolder the base and just make sure it's not making a connection that's fine, but either way you should still be able to track a signal up to that point "BASE" and see the signal with no power applied to the radio.