Re: TR-4C problem on 40 meters FIXED
Sorry Tom, I hijacked the thread! Of course, my problem did
affect all bands.
Couldn't resist when I read about a solder joint problem.
73, Dieter DL5RDO
Am 30.12.2024 um 14:46 schrieb Tom
Smith:
toggle quoted message
Show quoted text
Why would this only affect 40m? It would seem to me that a PTO problem would affect all bands.
Thanks and happy new year to all!
|
Re: TR-4C problem on 40 meters FIXED
Well done, Jim! :-)
Am 30.12.2024 um 05:50 schrieb Jim
Shorney via groups.io:
toggle quoted message
Show quoted text
There are a few areas of concern but the main fracture is pretty obvious.
On Mon, 30 Dec 2024 01:17:58 +0000
"Stan Gammons via groups.io" <buttercup11421@...> wrote:
The big glob under the coil doesn't look good or does the connections through the ceramic under the coil. The solder joint immediately behind the opening in the middle of the ceramic doesn't look good either or does the solder joint behind it.
73
Stan
KM4HQE
|
Re: TR-4C problem on 40 meters FIXED
"The solder joint immediately behind the opening in the middle of
the ceramic doesn't look good either..."
You got it, Stan! That was the one! No clue how such things
happen but it was pretty obvious once I found it...
But isn't it wonderful to be able to bring all these Drakes back
to life...?? Try that with a TS990 in 50 years! ;-)
73, Dieter DL5RDO
Am 30.12.2024 um 02:17 schrieb Stan
Gammons via groups.io:
toggle quoted message
Show quoted text
The big glob under the coil doesn't look good or does the
connections through the ceramic under the coil.? The solder joint
immediately behind the opening in the middle of the ceramic
doesn't look good either or does the solder joint behind it.
73
Stan
KM4HQE
On 12/29/24 16:20, Dieter Horst
wrote:
I had one in a PTO, too! Every now and then, its level was
way down and the R4C's sensitivity with it...? Hitting on the
side of the RX would cure it for a while. But... thou shalt
not beat your Drakes! So I had to open up the PTO and find the
culprit. I didn't take long until I found the bad connection.
Who can spot it? See attached (and have fun!).
73, Dieter DL5RDO
Am 29.12.2024 um 19:01 schrieb Jim
Shorney via groups.io:
Solder connections can develop fractures that are hard to see even with magnification. I had one in a PTO that was only visible from a certain angle, otherwise the connection looked good.
On Sun, 29 Dec 2024 07:35:42 -0800
"Richard Knoppow via groups.io" <1oldlens1@...> wrote:
Congratulations! Its fairly common for their to be cold solder
joints that look fine. Sometimes they show up if you poke around the
circuit with an insulated stick like a chop stick.
On 12/29/2024 2:29 AM, Peter Ravn via groups.io wrote:
I tested contacts, inductance and resistance in all parts used on 40
meters only. While doing so I lifted all leads that might affect the
measurements. This brought 40 meters back to life. Miracles never cease.
Peter OZ8CTH
|
Re: Looking for advice on T4XB issues
Steve,
?
Did the reset thing. The radio is working normally (I forgot that Tune mode is different than CW mode and I adjusted the gain to get the output in CW).
?
I need to get some new DeOxit as the one I have is old and lost pressure. It just dribbles out HIHI!
?
Not tossing the 12AX7, but leaving the new one in.
?
The twins are set for SKN! Really like the blue LEDs.
?
Jason N8XE
|
A while back, I too, had the same problem with the BFO not working. I checked each and every part in the circuit and couldn’t find a thing wrong with it.?
My fix?
I added a small value electrolytic capacitor to the VCC line, if I remember 22 or 47 mFd.
And that fixed the problem.?
I have no idea what the added capacitor started the oscillator, but it has worked ever since.
mike, wb8vge
toggle quoted message
Show quoted text
On Dec 30, 2024, at 10:18 AM, Dave W7GZ via < w7gz@...> wrote:
Many tnx reply, Steve. Mine is an 11-tube with S/N 6717B. How does it compare in age to yours? It works fine with the pull-down resistor now, before I had to wait many minutes, sometimes forever for the BFO to start.
?
This one is an interesting specimen. It was sold to me for dirt cheap as a parts radio because it had been left in humidity and has quite a bit of rust on the top surface, but underneath it is pristine. After replacing 5 tubes that had vented through their pins, I discovered it was actually a working set. Not as nice looking as my R-4C, but it is completely usable and sensitive.
?
Thanks for posting your issue, it helped me realize it has been seen before. Dave
|
Many tnx reply, Steve. Mine is an 11-tube with S/N 6717B. How does it compare in age to yours? It works fine with the pull-down resistor now, before I had to wait many minutes, sometimes forever for the BFO to start.
?
This one is an interesting specimen. It was sold to me for dirt cheap as a parts radio because it had been left in humidity and has quite a bit of rust on the top surface, but underneath it is pristine. After replacing 5 tubes that had vented through their pins, I discovered it was actually a working set. Not as nice looking as my R-4C, but it is completely usable and sensitive.
?
Thanks for posting your issue, it helped me realize it has been seen before. Dave
|
Re: Looking for advice on T4XB issues
As the problem emerged after removing the covers, a cursory search for things that may have moved initially makes sense. Don’t toss that 12AX7 quite yet (the audiophools have made them far too expensive).?
Try reseating all of the tubes except for the finals (in the interest of quickly running down the list). DeOxIt on the tube pins can help here.?
Next is to check that all Of the oscillators are working. The CO can be checked at the cathode — top connection of the 5645 Xtal. Band oscillator at the wiper arm near the band crystals.?
A scope comes in handy here but you can use a counter.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Dec 30, 2024 at 09:43, Jason Hissong via groups.io < jhissong@...> wrote:
Doing some more research on this message list, I replaced V9 with a different 12AX7 and the sidetone and CW works normally now. However, still getting no change on the gain control when trying to tune. I do see a little blip on the meter when I use CW, but still no change. I will keep digging.
?
I did look to see if I messed anything up trying to get the light assembly for the meter connected. I don't see anything obvious.
?
Any tips or advice is welcome!
?
Jason N8XE
|
Re: Looking for advice on T4XB issues
Doing some more research on this message list, I replaced V9 with a different 12AX7 and the sidetone and CW works normally now. However, still getting no change on the gain control when trying to tune. I do see a little blip on the meter when I use CW, but still no change. I will keep digging.
?
I did look to see if I messed anything up trying to get the light assembly for the meter connected. I don't see anything obvious.
?
Any tips or advice is welcome!
?
Jason N8XE
|
Re: TR-4C problem on 40 meters FIXED
Why would this only affect 40m? It would seem to me that a PTO problem would affect all bands.
Thanks and happy new year to all!
|
I never did figure out why. ?The receiver (11-tube and late s/n) is still working fine.
On Sun, Dec 29, 2024 at 8:10 PM, Dave W7GZ via groups.io < w7gz@...> wrote:
Steve, did you ever figure out this behavior? My R-4A BFO has identical symptoms to yours. I fixed it by adding a 1K resistor to pull down the Vcc on Q6, but why does the transistor oscillate at 6V but not at 10V Vcc? I didn't check every component around Q6, but they don't look cooked. It was puzzling to have to park the mode switch halfway between AM and SSB to get BFO.
?
Dave
|
Gary I just checked that voltage again with the band switch on 10 meters and the DC voltage at that RFC505 is 20.52 DC. Hope that helps.
Jim VE1RB
On Sun, Dec 29, 2024 at 8:37?PM Gary Follett via <xntrick1948= [email protected]> wrote: What is the voltage on RFC 505?
Gary
W0DVN
Worked on the VCO board today and founds that the 5 volt regulator is working just fine 5.02 VDC. So am thinking about it trying to decide what I check next. Might make a chart of voltages on the transistors from the working one and compare to the non working section.
73, Jim Ve1RB On Sat, Dec 28, 2024 at 11:08?PM Gary Follett via ??<xntrick1948= [email protected]> wrote: The power supply that is the subject of this issue is the 7805 regulator on the VCO board. That is the one that denies power to just the one VCO (high bands, in this case) when it fails.
Regards,
Gary
W0DVN On Dec 28, 2024, at 8:28?PM, Tony N5DIM < tony@...> wrote:
The WB4HFN website has a section with great information related to that power supply board. I just used it to resurrect a TR7 that was DOA. Good luck. 73 Tony N5DIM? On Dec 28, 2024, at 5:52?PM, Gary Follett via??<xntrick1948=[email protected]> wrote:
?Sounds like you are on the right track. Don’t ocelot the electrolytic capacitors on that supply as well.
Gary
W0DVN
Gary, I found a few minutes to work on the TR7 and discovered that the high VCO is not working at all. It does have the 10 vdc supply switch?on it but I don't know if that reulagor?is working or not. I will check it out but have to work on getting the metal shield off. I Hope that is the problem but I will work on it maybe tomorrow. Thanks for all your help.
73, Jim VE1RB On Fri, Dec 27, 2024 at 9:06?PM Gary Follett via ??<xntrick1948= [email protected]> wrote: It is worth asking, did the failure of your VCO board (displaying 51.950) occur on its own? That is to ask, did the radio work properly and then just fail or has it, as long as you have had it, always operated with this fault??
If it once worked for you and then failed, then it would make sense to see what gets disconnected if those pins are not in line ?and look for a way that same thing could happen without the pin alignment problem.
The pin alignment fix is pretty easy though, if the board alignment is the cause. It just SOUNDS difficult.
That whole DR7 was always a source of issues due to its complexity and difficulty of installation. I don’t know how a DR7 could even endure the stresses of removal and reinsertion more than once!
Gary?
W0DVN
Thanks Tom. I printed that off but hope that is not the problem.
73, Jim VE1RB In 2010 there was a thread regarding the Drake TR-7 display showing 51950.0 on the old retired Drakelist.
The thread is archived at?
Please click the link so the owner knows that we find the archive useful.
Hope this helps. Tom, AG9X
================? Below are the posts from Brian Koontz WA3ITE, Jim Shorney NU0C and Garey Barrell K4OAH (SK)? (just in case Drake TR-7 DR-7 problems outlive the??site)
Re: [Drakelist] Almost there: TR-7 display issues -- FIXED!
Brian Koontz Fri, 30 Jul 2010 20:36:54 -0700
Well, the TR-7 from hell is now a fully operational TR-7 from hell!
In preparation for some signal tracing, I decided to extend the DR-7
board using the extenders I have.? To do this, you have to unmount the
two voltage regulators mounted to the chassis, and jumper the
connector farthest to the right. ?(I didn't bother connecting the
up/down band buttons.) ?Lo and behold, the display worked!?
Some further investigation revealed that the chassis has warped over
the years, so the two 3-prong connectors on the VCO board were no
longer in a horizontal line.? So I was determined to make sure the
board was fully seated on all the connectors.
To do this, I had to drop the front panel.? Not a major chore, just
one knob to remove (the band knob) and 6 side screws. With that now
out of the way, it was an easy job to determine if all the pins were
where they belonged.? The only snag was that the front panel, when
canted downwards, angles the PTO can upwards.? So you have to hold the
front panel perpendicular and steady with slight downward pressure to
fully seat the board.? Once all the pins were visually confirmed to be
seated, I remounted the front panel, reattached the regulators and all
the connectors, and fired the rig up.? Everything now seems to work!
It turns out the original DR-7 board was indeed defective as well
(possibly because it had been seated incorrectly).? And a visual
confirmation from topside indicates the chassis is, indeed, warped:
The screw hole is misaligned with the mounting hole in the board.?
So, for archival purposes in case anyone else decides to search for
this problem: ?If the display if fixed on "51950", one possible cause
is that one or more DR-7 pins, possibly the VCO pins, are not
correctly seated.? The best solution is to drop the front panel and
confirm visually that the pins are fully seated.
Now it's time to get on the air!
??--Brian/WA3ITE
=================?
Jim Shorney Fri, 30 Jul 2010 23:17:58 -0700
On Fri, 30 Jul 2010 20:40:52 -0500, Brian Koontz wrote:
>Well, the TR-7 from hell is now a fully operational TR-7 from hell!
>
>Now it's time to get on the air!
Congratulations, Brian! You have been assimilated into the collective.
Resistance is futile.
73
-Jim
================= ? Garey Barrell ?k4oah@...?via ?Sat, Jul 31, 2010, 8:34?AM to drakelist Brian Koontz wrote: > Some further investigation revealed that the chassis has warped over > the years, so the two 3-prong connectors on the VCO board were no > longer in a horizontal line.? So I was determined to make sure the > board was fully seated on all the connectors. > > > > So, for archival purposes in case anyone else decides to search for > this problem: ?If the display is fixed on "51950", one possible cause > is that one or more DR-7 pins, possibly the VCO pins, are not > correctly seated.? The best solution is to drop the front panel and > confirm visually that the pins are fully seated. >
Brian -
Congratulations!! ? It's always nice when one 'comes together'.
Just as an aside, someone suggested earlier (and correctly) that the
"51950" problem may indicate a loss of the 500 kHz reference signal.?
You might find it interesting that the left-most three pin connector on
the VCO board is the 500 kHz reference signal!
Those pins on the bottom of the DR-7 are ALWAYS a problem, ya' just
can't see 'em!!
Your 'trials' have been an interesting 'trip' for others, thanks for
documenting it for us all.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& ?TR-4/C Service Supplement CDs
<>
=================
? Search terms to make this post easier to find:? Drake TR-7 TR7 DR-7 DR7 display frozen locked stuck ? 51950?? 51,950?? 51 950?? 5195? 51950.0 ? 51,950.0 ? 51 950 0
???
|
Plus 20.61 Volts DC. Or did you want RF volts? I don't have an RF probe.
Jim VE1RB
On Sun, Dec 29, 2024 at 8:37?PM Gary Follett via <xntrick1948= [email protected]> wrote: What is the voltage on RFC 505?
Gary
W0DVN
Worked on the VCO board today and founds that the 5 volt regulator is working just fine 5.02 VDC. So am thinking about it trying to decide what I check next. Might make a chart of voltages on the transistors from the working one and compare to the non working section.
73, Jim Ve1RB On Sat, Dec 28, 2024 at 11:08?PM Gary Follett via ??<xntrick1948= [email protected]> wrote: The power supply that is the subject of this issue is the 7805 regulator on the VCO board. That is the one that denies power to just the one VCO (high bands, in this case) when it fails.
Regards,
Gary
W0DVN On Dec 28, 2024, at 8:28?PM, Tony N5DIM < tony@...> wrote:
The WB4HFN website has a section with great information related to that power supply board. I just used it to resurrect a TR7 that was DOA. Good luck. 73 Tony N5DIM? On Dec 28, 2024, at 5:52?PM, Gary Follett via??<xntrick1948=[email protected]> wrote:
?Sounds like you are on the right track. Don’t ocelot the electrolytic capacitors on that supply as well.
Gary
W0DVN
Gary, I found a few minutes to work on the TR7 and discovered that the high VCO is not working at all. It does have the 10 vdc supply switch?on it but I don't know if that reulagor?is working or not. I will check it out but have to work on getting the metal shield off. I Hope that is the problem but I will work on it maybe tomorrow. Thanks for all your help.
73, Jim VE1RB On Fri, Dec 27, 2024 at 9:06?PM Gary Follett via ??<xntrick1948= [email protected]> wrote: It is worth asking, did the failure of your VCO board (displaying 51.950) occur on its own? That is to ask, did the radio work properly and then just fail or has it, as long as you have had it, always operated with this fault??
If it once worked for you and then failed, then it would make sense to see what gets disconnected if those pins are not in line ?and look for a way that same thing could happen without the pin alignment problem.
The pin alignment fix is pretty easy though, if the board alignment is the cause. It just SOUNDS difficult.
That whole DR7 was always a source of issues due to its complexity and difficulty of installation. I don’t know how a DR7 could even endure the stresses of removal and reinsertion more than once!
Gary?
W0DVN
Thanks Tom. I printed that off but hope that is not the problem.
73, Jim VE1RB In 2010 there was a thread regarding the Drake TR-7 display showing 51950.0 on the old retired Drakelist.
The thread is archived at?
Please click the link so the owner knows that we find the archive useful.
Hope this helps. Tom, AG9X
================? Below are the posts from Brian Koontz WA3ITE, Jim Shorney NU0C and Garey Barrell K4OAH (SK)? (just in case Drake TR-7 DR-7 problems outlive the??site)
Re: [Drakelist] Almost there: TR-7 display issues -- FIXED!
Brian Koontz Fri, 30 Jul 2010 20:36:54 -0700
Well, the TR-7 from hell is now a fully operational TR-7 from hell!
In preparation for some signal tracing, I decided to extend the DR-7
board using the extenders I have.? To do this, you have to unmount the
two voltage regulators mounted to the chassis, and jumper the
connector farthest to the right. ?(I didn't bother connecting the
up/down band buttons.) ?Lo and behold, the display worked!?
Some further investigation revealed that the chassis has warped over
the years, so the two 3-prong connectors on the VCO board were no
longer in a horizontal line.? So I was determined to make sure the
board was fully seated on all the connectors.
To do this, I had to drop the front panel.? Not a major chore, just
one knob to remove (the band knob) and 6 side screws. With that now
out of the way, it was an easy job to determine if all the pins were
where they belonged.? The only snag was that the front panel, when
canted downwards, angles the PTO can upwards.? So you have to hold the
front panel perpendicular and steady with slight downward pressure to
fully seat the board.? Once all the pins were visually confirmed to be
seated, I remounted the front panel, reattached the regulators and all
the connectors, and fired the rig up.? Everything now seems to work!
It turns out the original DR-7 board was indeed defective as well
(possibly because it had been seated incorrectly).? And a visual
confirmation from topside indicates the chassis is, indeed, warped:
The screw hole is misaligned with the mounting hole in the board.?
So, for archival purposes in case anyone else decides to search for
this problem: ?If the display if fixed on "51950", one possible cause
is that one or more DR-7 pins, possibly the VCO pins, are not
correctly seated.? The best solution is to drop the front panel and
confirm visually that the pins are fully seated.
Now it's time to get on the air!
??--Brian/WA3ITE
=================?
Jim Shorney Fri, 30 Jul 2010 23:17:58 -0700
On Fri, 30 Jul 2010 20:40:52 -0500, Brian Koontz wrote:
>Well, the TR-7 from hell is now a fully operational TR-7 from hell!
>
>Now it's time to get on the air!
Congratulations, Brian! You have been assimilated into the collective.
Resistance is futile.
73
-Jim
================= ? Garey Barrell ?k4oah@...?via ?Sat, Jul 31, 2010, 8:34?AM to drakelist Brian Koontz wrote: > Some further investigation revealed that the chassis has warped over > the years, so the two 3-prong connectors on the VCO board were no > longer in a horizontal line.? So I was determined to make sure the > board was fully seated on all the connectors. > > > > So, for archival purposes in case anyone else decides to search for > this problem: ?If the display is fixed on "51950", one possible cause > is that one or more DR-7 pins, possibly the VCO pins, are not > correctly seated.? The best solution is to drop the front panel and > confirm visually that the pins are fully seated. >
Brian -
Congratulations!! ? It's always nice when one 'comes together'.
Just as an aside, someone suggested earlier (and correctly) that the
"51950" problem may indicate a loss of the 500 kHz reference signal.?
You might find it interesting that the left-most three pin connector on
the VCO board is the 500 kHz reference signal!
Those pins on the bottom of the DR-7 are ALWAYS a problem, ya' just
can't see 'em!!
Your 'trials' have been an interesting 'trip' for others, thanks for
documenting it for us all.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& ?TR-4/C Service Supplement CDs
<>
=================
? Search terms to make this post easier to find:? Drake TR-7 TR7 DR-7 DR7 display frozen locked stuck ? 51950?? 51,950?? 51 950?? 5195? 51950.0 ? 51,950.0 ? 51 950 0
???
|
TR-5 BPF AMP Board Oddness
I dove into my original TR-5 (s/n 1051) to try to figure out why
it stopped txing. I decided to start with a full re-aligment as
per the manual. While looking through the manual, I discovered the
BPF Amp board looks different from the picture in the manual (and
from the schematic).
Instead of the two vertical rows of three cans below the two
horizontal rows of three, I have a two by two grid of larger cans
below the two horizontal rows. This doesn't match the pictures or
the schematic. This messes up the the front end alignment step
(section 5-6.5), since L703, 4, 5, 6, 23, and 24 don't exist, being
replaces by the four mystery xfmrs.
Anybody know what's going on here? I have another TR-5 (s/n 1024)
that I got from Steve; I haven't opened it up yet to see if it's
the same.
--lyndon
|
Looking for advice on T4XB issues
Hello everyone,
?
I am getting prepared for SKN so I decided to finally put the blue LEDs from Radio Lab Works into the T4XB. Prior to this, the twins worked fine on both SSB and CW. After replacing the LEDs, the T4XB is not working correctly. Let me explain:
?
When I try to tune the T4XB on my desired band, the gain control does not seem to increase the plate current at all (per the instructions, you raise the gain one unit, adjust the RF tune to raise the plate current to 1.5 amps and quickly adjust the plate to dip the current). It stays at .07A on the meter. I am tuning into a dummy load.?
?
CW does not work right at all. When I turn the Vox up all the way, it will hold and then drop after a second or two. Sometimes it will start transmitting again for half a second and then stop.
?
There is no sidetone going to the R4XB at all no matter what the Anti-Vox/Sidetone is set at.
?
I made sure the connections between the T4XB and R4XB were correct. Transceive appears to be working correctly. Receiver mute works.
?
All I did was remove the cover, replace the lights (and the blue filters) and put it back together again. Now I did have to remove the bottom cover because of a lost standoff when removing the VFO dial blue gel.
?
I am wondering if I knocked something loose (specifically on the Gain control). I am going to open it back up tomorrow and see if there is anything obvious. I may need to swap out the 4B line with the 4C for SKN!! :)
?
Thanks es 73,
?
Jason N8XE
|
Re: TR-4C problem on 40 meters FIXED
There are a few areas of concern but the main fracture is pretty obvious. On Mon, 30 Dec 2024 01:17:58 +0000 "Stan Gammons via groups.io" <buttercup11421@...> wrote: The big glob under the coil doesn't look good or does the connections through the ceramic under the coil. The solder joint immediately behind the opening in the middle of the ceramic doesn't look good either or does the solder joint behind it.
73
Stan
KM4HQE -- 73 -Jim NU0C
|
It should come off if all the screws are out. Your heatsink goop may have turned into cement. You could probably loosen it up by applying heat to the heat sink with a heat gun or hair dryer. If the thermal compound is that bad it probably should be cleaned off and refreshed with a thin coating of new. However, you do not need to take the board off to replace the regulator. The component leads are flat soldered to the top side. You do need to take care though that you do not rip the top side traces off. On Sun, 29 Dec 2024 15:45:55 -0800 "Craig W8CS via groups.io" <craig_severson@...> wrote: Folks...for those who have dived into the Final Amp section of the TR-7A, is there a trick to getting to the back of the PA board/removing the heat sink?
I have removed all of the mounting screws, including those for the TO-220 transistors, as well as the small allen heads which ground the final amp emitters. Won't budge and am concerned about cracking the board. I am trying to replace the +5V regulator U2301 and my assumption is that I need to unsolder it from the back side. -- 73 -Jim NU0C
|
Re: TR-4C problem on 40 meters FIXED
Yes I see it. That one is pretty obvious. The one I found had the cut end of a component lead in the same area that was bent over a little like it was struck by something. From convenient angles it looked OK but if you looked at it just right you could see the solder fractured around the component lead. I may have a photo somewhere but it will take some time to find it. On Sun, 29 Dec 2024 23:20:07 +0100 "Dieter Horst via groups.io" <dieter.horst@...> wrote: Who can spot it? See attached (and have fun!). -- 73 -Jim NU0C
|
Re: TR-4C problem on 40 meters FIXED
The big glob under the coil doesn't look good or does the
connections through the ceramic under the coil.? The solder joint
immediately behind the opening in the middle of the ceramic doesn't
look good either or does the solder joint behind it.
73
Stan
KM4HQE
On 12/29/24 16:20, Dieter Horst wrote:
toggle quoted message
Show quoted text
I had one in a PTO, too! Every now and then, its level was way
down and the R4C's sensitivity with it...? Hitting on the side
of the RX would cure it for a while. But... thou shalt not beat
your Drakes! So I had to open up the PTO and find the culprit. I
didn't take long until I found the bad connection.
Who can spot it? See attached (and have fun!).
73, Dieter DL5RDO
Am 29.12.2024 um 19:01 schrieb Jim
Shorney via groups.io:
Solder connections can develop fractures that are hard to see even with magnification. I had one in a PTO that was only visible from a certain angle, otherwise the connection looked good.
On Sun, 29 Dec 2024 07:35:42 -0800
"Richard Knoppow via groups.io" <1oldlens1@...> wrote:
Congratulations! Its fairly common for their to be cold solder
joints that look fine. Sometimes they show up if you poke around the
circuit with an insulated stick like a chop stick.
On 12/29/2024 2:29 AM, Peter Ravn via groups.io wrote:
I tested contacts, inductance and resistance in all parts used on 40
meters only. While doing so I lifted all leads that might affect the
measurements. This brought 40 meters back to life. Miracles never cease.
Peter OZ8CTH
|
Steve, did you ever figure out this behavior? My R-4A BFO has identical symptoms to yours. I fixed it by adding a 1K resistor to pull down the Vcc on Q6, but why does the transistor oscillate at 6V but not at 10V Vcc? I didn't check every component around Q6, but they don't look cooked. It was puzzling to have to park the mode switch halfway between AM and SSB to get BFO.
?
Dave
|
Re: TR-4C problem on 40 meters FIXED
Lead next to the screw bottom left. Looks like a piece is clipped off.
toggle quoted message
Show quoted text
On 12/29/2024 2:20 PM, Dieter Horst wrote: I had one in a PTO, too! Every now and then, its level was way down and the R4C's sensitivity with it...? Hitting on the side of the RX would cure it for a while. But... thou shalt not beat your Drakes! So I had to open up the PTO and find the culprit. I didn't take long until I found the bad connection.
Who can spot it? See attached (and have fun!).
73, Dieter DL5RDO
Am 29.12.2024 um 19:01 schrieb Jim Shorney via groups.io:
Solder connections can develop fractures that are hard to see even with magnification. I had one in a PTO that was only visible from a certain angle, otherwise the connection looked good.
On Sun, 29 Dec 2024 07:35:42 -0800
"Richard Knoppow via groups.io"<1oldlens1@...> wrote:
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Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Jim Shorney
