Re: R7 Multi-Vibrator Harmonics
OK... thanks for the info.? I haven't found that information yet.? I'll try again to get the power supply board out.? I haven't?had much luck pulling it out.?? I know you pull it straight?up but it won't come out.? It pulls up about an 1/8 inch off of the base connector then wont' move any farther.? I'll have to? look at it?again, but can't see anything blocking its path.? I don't want to destroy it with too much force.? Can't use the card puller.
Dan
Which part are you asking is normal? The oscillator is free running, so yes it is normal to drift a bit. However it is NOT normal for you to be able to hear it in the RX. That is a symptom of failing filter capacitors on the PS board. This has been covered in previous postings in this forum.
On Thu, 1 May 2025 17:17:08 -0400
"Daniel W3DF via " <danflan49=[email protected]> wrote:
> My R7 is working well, it seems.? I am now running it on DC voltage.? The
> multi-vibrator runs at about 28khz after it has been running for a while.
> It starts at about 24 khz when the R7 is first turned on.
>
> With no antenna connected I can still hear the harmonics drift across a
> frequency on 40M.? I don't notice them with an antenna connected.? And of
> course, they get stronger as you go to the lower bands.
>
> Is this normal?
>
> Dan (W3DF)
--
73
-Jim
NU0C
|
Hi everyone. I am reporting to you because you offered such good advice. I have found the problem and fixed it but I am embarrassed?to disclose that it was the relay. I had cleaned it thoroughly (I thought) but after eliminating everything else, an Elmer suggested that I revisit the relay. So after spending almost an hour gaining access, cleaning contacts again, and some minor adjustments, my TR-3 works and works well. Thank you all again.
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Re: R7 Multi-Vibrator Harmonics
Which part are you asking is normal? The oscillator is free running, so yes it is normal to drift a bit. However it is NOT normal for you to be able to hear it in the RX. That is a symptom of failing filter capacitors on the PS board. This has been covered in previous postings in this forum. On Thu, 1 May 2025 17:17:08 -0400 "Daniel W3DF via groups.io" <danflan49@...> wrote: My R7 is working well, it seems. I am now running it on DC voltage. The
multi-vibrator runs at about 28khz after it has been running for a while.
It starts at about 24 khz when the R7 is first turned on.
With no antenna connected I can still hear the harmonics drift across a
frequency on 40M. I don't notice them with an antenna connected. And of
course, they get stronger as you go to the lower bands.
Is this normal?
Dan (W3DF) -- 73 -Jim NU0C
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Drake TR3 Smoked Resistor
I'm working on bringing a Drake TR3 back to life. During power up I noticed smoke coming from below the chassis. I quickly powered the TR3 off. I turned the TR3 upside down, front panel facing me, and found a 1/2W resistor that had overheated. The picture below shows the location of this resistor. Does anyone know the resistor's value and where on the schematic it's located? The Yellow shaft is used as a pointer and the Black arrow is also pointing to the resistor. It's to the "Left" of the audio transformer and between the 2 small PC boards. I need to determine what that resistor is so I can find it on the TR3 schematic then track down what caused it to over heat. The TR3 was in "receive" when the resistor overheated. There was no audio heard in the speaker. The 8 pin remote VFO plug was in place with pin 2 connected to pin 8 as shown on the TR3 schematic (the RV3 was not plugged into the remote VFO socket). Any help would be appreciated. Please reply direct to my email address. 73 Mike W5RKL 
|
Fellow Drake Enthusiasts,
The D-104 Final Edition microphone and the Shure 450 version II have been spoken for from the list I posted on the reflector and the QTH.com ad. ?The other items are still available.
73,
Evan, K9SQG
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R7 Multi-Vibrator Harmonics
My R7 is working well, it seems.? I am now running it on DC voltage.? The multi-vibrator runs at about 28khz after it has been running for a while.? It starts at about 24 khz when the R7 is first turned on.
With no antenna connected I can still hear the harmonics drift across a frequency on 40M.? I don't notice them with an antenna connected.? And of course, they get stronger as you go to the lower bands.
Is this normal?
Dan (W3DF)
|
Interesting post on setting TR7 8.05 oscillator.
Found this on zerobeat under Drake Mods by VE3EFJ:
?
- 8.05 MHz Osc Won't Net
This oscillator is varicap controlled and is used in conjunction with the 13.995 fixed oscillator to develop the BFO. In doing it this way, there is little chance that there will be BFO leakage, or what leakage there is, can be controlled.
There is a trimmer adjustment to net the 8.05 MHz crystal, but what the manual fails to tell you is that this adjustment is also affected by the trim pots for the injection frequencies for the BFO.
If you try to set this trimmer up and it just won't trim, try an arbitrary setting of the trimmer screw and see if, say, on LSB you can get it to the proper frequency with the trim pot for that mode.
Would this actually work?? If the best one can net the crystal is say around 5.646 instead of 5.645 will the rig work correctly? if the trim pots on the power supply board for USB, LSB, CW, RTTY and AM will all adjust to the proper frequencies?? Seems a lot easier than trial and error padding of C1029.
?
73, Bill NZ0T
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Re: Another TR7 Journey begins
If the rig did not turn on you were either on the wrong pin or you had a poor connection. The TR7 is a top notch rig and will run circles around many "modern" radios. They are well worth repairing. Once you understand how they work it is not so difficult. I was scared to death of my first one. Until I wasn't. On Wed, 30 Apr 2025 09:45:38 -0700 "Bill NZ0T via groups.io" <nz0tham@...> wrote: I did try using the low current pin and ground but that was with a separate PS, not the PS7 and the rig would not come on.? Should have used the PS7 I guess but the high current tap was easy enough to unsolder and I'll likely be taking the entire power module out anyway.? ?Guess I'll have to take the LPF module out again - hopefully without having to unsolder any wires - and figure out what the deal is with the 40M issue.
If I had any idea how challenging this rig would be to get going I would never have bought it lol.? And I really wish I had not sent it to a certain long time Drake tech who sent it back in worse shape telling me it was unrepairable.? Which cost me about $200 with shipping and his fee.? I'm to the point of selling it as is or trying to find somebody else who is a trusted Drake tech to look at it.
73, Bill NZ0T -- 73 -Jim NU0C
|
I think I verified that as well a few weeks ago.? Thanks for the confirmation.
Barry - N4BUQ
Barry: Per Garey's schematics,?I see V-11 changing at #26,000 to a 12BZ6....so yours would agree with that change. 73 Peter VE7PS
The serial number for my TR-4 is 26040 which is presumably a Version 3 rig.
According to Garey's TR-4 documentation, V11 switched from a 12BA6 to a 12BZ6 at Version 4 (S/N 27000) but my TR-4's V11 is a 12BZ6 (not just the tube but the label beside its socket as well).
Is it possible Garey's chart is incorrect or am I misunderstanding it?? I found the following comment from Garey as well:
/g/DRAKE-RADIO/message/13132
I'm just curious as to the apparent discrepancy.? Anyone know?
Thanks,
Barry - N4BUQ
|
Barry:
Per Garey's schematics,?I see V-11 changing at #26,000 to a 12BZ6....so yours would agree with that change.
73 Peter VE7PS
The serial number for my TR-4 is 26040 which is presumably a Version 3 rig.
According to Garey's TR-4 documentation, V11 switched from a 12BA6 to a 12BZ6 at Version 4 (S/N 27000) but my TR-4's V11 is a 12BZ6 (not just the tube but the label beside its socket as well).
Is it possible Garey's chart is incorrect or am I misunderstanding it?? I found the following comment from Garey as well:
/g/DRAKE-RADIO/message/13132
I'm just curious as to the apparent discrepancy.? Anyone know?
Thanks,
Barry - N4BUQ
|
The serial number for my TR-4 is 26040 which is presumably a Version 3 rig. According to Garey's TR-4 documentation, V11 switched from a 12BA6 to a 12BZ6 at Version 4 (S/N 27000) but my TR-4's V11 is a 12BZ6 (not just the tube but the label beside its socket as well). Is it possible Garey's chart is incorrect or am I misunderstanding it? I found the following comment from Garey as well: /g/DRAKE-RADIO/message/13132I'm just curious as to the apparent discrepancy. Anyone know? Thanks, Barry - N4BUQ
|
Re: TR-4 Decreased Sensitivity on High Bands
The main time I will suspect alignment is if a PO tried to align it to try and repair it.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Wednesday, April 30th, 2025 at 5:11 PM, n4buq <n4buq@...> wrote:
Radios typically don't just fall out of alignment so it makes sense that an alignment might not be necessary unless something weird happens.? I'm almost certain I had better output - at least on the lower bands - and this behavior began after I've been into it.? I'll keep at it.? I haven't tried wiggling the "towers" but maybe I'll find something there.? I know getting the alignment load clipped to V3 was tight so I need to look there as well.
Thanks again, Barry Barry:
I was not certain whether or not the radio ever worked properly for you. If a radio worked well, then failed, it would be highly unlikely for alignment to be an issue. However, if the radio has never worked properly for you, then alignment would seem to be a good thing to try.
Gary
W0DVN
On Apr 30, 2025, at 3:42?PM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
I have at least one intermittent component, in addition to 15/10 deafness/low power out.
I found some sensitivity when moving the "tower" under the 6EJ7.? Resoldered everything around it and measured the resistors, which are "close enough".? Can only get around 50W out on 15, with 250 mA of current.? Could be soft finals.
The xtal oscillators have sufficient amplitude.? When the rig goes deaf, 20 and 80 are deaf, as well.
There's definitely more than one and probably more than two problems here and one is intermittent!
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Wednesday, April 30th, 2025 at 2:29 PM, n4buq <n4buq@...> wrote:
Hi Gary, If there are problems with the radio, I'm curious why the recommendation is not to align it.? I realize that it's easy to misalign it but if the procedures in the manual are followed, then what harm is it to do that?? I understand that a properly adjusted coil/transformer is likely never to go very far out of adjustment on its own but it's also difficult to know whether someone has golden-screwdrivered the rig as well. Just curious. Thanks, Barry - N4BUQ
That leaves the RF coils as suspect. While I generally do not recommend aligning a radio that once worked and now does not work, in this case you can pick a band that produces some measurable output and adjust the RF coils just a little, keeping track of how much you moved them. Any properly aligned coil should show a drop in output either side of the starting position.?
If you have a piece of brass and a piece of ferrite that will?fit into the adjustment holes, you can insert these into the coils without moving the coil slugs themselves. Inserting the brass will rise the tuned circuit frequency, inserting ferrite will lower that resonant frequency, performing the same test without physically moving the coil slugs¡ Insertion of either should reduce output of the radio if it is properly aligned already. I have a tool for this purpose but that does you little good, sorry. Gary W0DVN On Apr 29, 2025, at 10:33?AM, n4buq <n4buq@...> wrote: Two minor clarifications: The cap across the neutralizing variable cap allows me to set a proper null so that the variable cap can swing through that at about the point where the rotor is meshed approximately half-way (it wouldn't do that with the original cap). The loading equipment for the injection coupler alignment is called an "alignment load", not necessarily a "dummy load" as I referred to it and I didn't want to cause confusion with the antenna dummy load (and I still wonder about the etymology of that phrase). Gary, This morning, as I tuned up (into a dummy load) across all bands and I noticed that the XMTR GAIN seems to saturate at about the same point for all bands.? I seem to recall that a few weeks ago (before I started touching up the alignment points), I could get a LOT more gain out of the lower bands. The only component work I've done is to replace the cap across the PA neutralizing cap and have that so I can minimize the spurious oscillations with the appropriate power peak at the valley (dip) of the plate tuning cap rotation.? I also replaced the cathode resistors with new 15R 1W metal film caps as the originals were out of spec and were not well-matched. Maybe I've botched the alignment(s) and, perhaps, I need to revisit those.? Disappointing as I'd hoped to make things better and apparently that's not the case but I don't yet know what I might have done wrong (yes, I did use the designated dummy load when tweaking the injection couplers which I know is essential to getting those correct). Thanks again,
Barry - N4BUQ
From: "Gary Follett via groups.io" <xntrick1948@...>
One test I have found to be useful is to plot output power on a given band versus position of the TX gain pot on the different bands. If you find that ?the saturation point of output (the point at which increasing the gain position produces no increase in output) versus position of the pot does not change as you go up in bands, then likely you have an alignment issue or a drive issue before the final mixer, because these earlier stages should produce more output than needed on the low bands to make up for poorer efficiency on the higher bands. In other words, you should be able to drive the heck out of the radio on 80 meters well before the saturation point of the TX gain pot.? Receiver gain issues track TX gain issues religiously. If TX gain is weak, receiver gain will be weak too. Gary W0DVN On Apr 28, 2025, at 7:44?PM, Ham Radio via groups.io <bernard.murphy@...> wrote: Steve: I assume you meant AGC. ? I have a TR-4 that has the same issue. ? Fine on TX but low on RX. ? See attached file.
--
73, Bernie. VE3FWF
Real?radios glow in the dark
<TR-4-tubes-sensitivity.xls>
|
Re: TR-4 Decreased Sensitivity on High Bands
Cleaned it once.? May try one last time.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Wednesday, April 30th, 2025 at 4:57 PM, Gary Follett via groups.io <xntrick1948@...> wrote:
Steve:
Have you tried cleaning the bandswitch?
Barry:
I was not certain whether or not the radio ever worked properly for you. If a radio worked well, then failed, it would be highly unlikely for alignment to be an issue. However, if the radio has never worked properly for you, then alignment would seem to be a good thing to try.
Gary
W0DVN
On Apr 30, 2025, at 3:42?PM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
I have at least one intermittent component, in addition to 15/10 deafness/low power out.
I found some sensitivity when moving the "tower" under the 6EJ7.? Resoldered everything around it and measured the resistors, which are "close enough".? Can only get around 50W out on 15, with 250 mA of current.? Could be soft finals.
The xtal oscillators have sufficient amplitude.? When the rig goes deaf, 20 and 80 are deaf, as well.
There's definitely more than one and probably more than two problems here and one is intermittent!
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Wednesday, April 30th, 2025 at 2:29 PM, n4buq <n4buq@...> wrote:
Hi Gary,
If there are problems with the radio, I'm curious why the recommendation is not to align it.? I realize that it's easy to misalign it but if the procedures in the manual are followed, then what harm is it to do that?? I understand that a properly adjusted coil/transformer is likely never to go very far out of adjustment on its own but it's also difficult to know whether someone has golden-screwdrivered the rig as well.
Just curious.
Thanks, Barry - N4BUQ
That leaves the RF coils as suspect. While I generally do not recommend aligning a radio that once worked and now does not work, in this case you can pick a band that produces some measurable output and adjust the RF coils just a little, keeping track of how much you moved them. Any properly aligned coil should show a drop in output either side of the starting position.?
If you have a piece of brass and a piece of ferrite that will?fit into the adjustment holes, you can insert these into the coils without moving the coil slugs themselves. Inserting the brass will rise the tuned circuit frequency, inserting ferrite will lower that resonant frequency, performing the same test without physically moving the coil slugs¡ Insertion of either should reduce output of the radio if it is properly aligned already. I have a tool for this purpose but that does you little good, sorry. Gary W0DVN On Apr 29, 2025, at 10:33?AM, n4buq <n4buq@...> wrote: Two minor clarifications: The cap across the neutralizing variable cap allows me to set a proper null so that the variable cap can swing through that at about the point where the rotor is meshed approximately half-way (it wouldn't do that with the original cap). The loading equipment for the injection coupler alignment is called an "alignment load", not necessarily a "dummy load" as I referred to it and I didn't want to cause confusion with the antenna dummy load (and I still wonder about the etymology of that phrase). Gary, This morning, as I tuned up (into a dummy load) across all bands and I noticed that the XMTR GAIN seems to saturate at about the same point for all bands.? I seem to recall that a few weeks ago (before I started touching up the alignment points), I could get a LOT more gain out of the lower bands. The only component work I've done is to replace the cap across the PA neutralizing cap and have that so I can minimize the spurious oscillations with the appropriate power peak at the valley (dip) of the plate tuning cap rotation.? I also replaced the cathode resistors with new 15R 1W metal film caps as the originals were out of spec and were not well-matched. Maybe I've botched the alignment(s) and, perhaps, I need to revisit those.? Disappointing as I'd hoped to make things better and apparently that's not the case but I don't yet know what I might have done wrong (yes, I did use the designated dummy load when tweaking the injection couplers which I know is essential to getting those correct). Thanks again,
Barry - N4BUQ
From: "Gary Follett via groups.io" <xntrick1948@...>
One test I have found to be useful is to plot output power on a given band versus position of the TX gain pot on the different bands. If you find that ?the saturation point of output (the point at which increasing the gain position produces no increase in output) versus position of the pot does not change as you go up in bands, then likely you have an alignment issue or a drive issue before the final mixer, because these earlier stages should produce more output than needed on the low bands to make up for poorer efficiency on the higher bands. In other words, you should be able to drive the heck out of the radio on 80 meters well before the saturation point of the TX gain pot.? Receiver gain issues track TX gain issues religiously. If TX gain is weak, receiver gain will be weak too. Gary W0DVN On Apr 28, 2025, at 7:44?PM, Ham Radio via groups.io <bernard.murphy@...> wrote: Steve: I assume you meant AGC. ? I have a TR-4 that has the same issue. ? Fine on TX but low on RX. ? See attached file.
--
73, Bernie. VE3FWF
Real?radios glow in the dark
<TR-4-tubes-sensitivity.xls>
|
Re: TR-4 Decreased Sensitivity on High Bands
Radios typically don't just fall out of alignment so it makes sense that an alignment might not be necessary unless something weird happens.? I'm almost certain I had better output - at least on the lower bands - and this behavior began after I've been into it.? I'll keep at it.? I haven't tried wiggling the "towers" but maybe I'll find something there.? I know getting the alignment load clipped to V3 was tight so I need to look there as well.
Thanks again, Barry
Barry:
I was not certain whether or not the radio ever worked properly for you. If a radio worked well, then failed, it would be highly unlikely for alignment to be an issue. However, if the radio has never worked properly for you, then alignment would seem to be a good thing to try.
Gary
W0DVN
On Apr 30, 2025, at 3:42?PM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
I have at least one intermittent component, in addition to 15/10 deafness/low power out.
I found some sensitivity when moving the "tower" under the 6EJ7.? Resoldered everything around it and measured the resistors, which are "close enough".? Can only get around 50W out on 15, with 250 mA of current.? Could be soft finals.
The xtal oscillators have sufficient amplitude.? When the rig goes deaf, 20 and 80 are deaf, as well.
There's definitely more than one and probably more than two problems here and one is intermittent!
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Wednesday, April 30th, 2025 at 2:29 PM, n4buq <n4buq@...> wrote:
Hi Gary, If there are problems with the radio, I'm curious why the recommendation is not to align it.? I realize that it's easy to misalign it but if the procedures in the manual are followed, then what harm is it to do that?? I understand that a properly adjusted coil/transformer is likely never to go very far out of adjustment on its own but it's also difficult to know whether someone has golden-screwdrivered the rig as well. Just curious. Thanks, Barry - N4BUQ
That leaves the RF coils as suspect. While I generally do not recommend aligning a radio that once worked and now does not work, in this case you can pick a band that produces some measurable output and adjust the RF coils just a little, keeping track of how much you moved them. Any properly aligned coil should show a drop in output either side of the starting position.?
If you have a piece of brass and a piece of ferrite that will?fit into the adjustment holes, you can insert these into the coils without moving the coil slugs themselves. Inserting the brass will rise the tuned circuit frequency, inserting ferrite will lower that resonant frequency, performing the same test without physically moving the coil slugs¡ Insertion of either should reduce output of the radio if it is properly aligned already. I have a tool for this purpose but that does you little good, sorry. Gary W0DVN On Apr 29, 2025, at 10:33?AM, n4buq <n4buq@...> wrote: Two minor clarifications: The cap across the neutralizing variable cap allows me to set a proper null so that the variable cap can swing through that at about the point where the rotor is meshed approximately half-way (it wouldn't do that with the original cap). The loading equipment for the injection coupler alignment is called an "alignment load", not necessarily a "dummy load" as I referred to it and I didn't want to cause confusion with the antenna dummy load (and I still wonder about the etymology of that phrase). Gary, This morning, as I tuned up (into a dummy load) across all bands and I noticed that the XMTR GAIN seems to saturate at about the same point for all bands.? I seem to recall that a few weeks ago (before I started touching up the alignment points), I could get a LOT more gain out of the lower bands. The only component work I've done is to replace the cap across the PA neutralizing cap and have that so I can minimize the spurious oscillations with the appropriate power peak at the valley (dip) of the plate tuning cap rotation.? I also replaced the cathode resistors with new 15R 1W metal film caps as the originals were out of spec and were not well-matched. Maybe I've botched the alignment(s) and, perhaps, I need to revisit those.? Disappointing as I'd hoped to make things better and apparently that's not the case but I don't yet know what I might have done wrong (yes, I did use the designated dummy load when tweaking the injection couplers which I know is essential to getting those correct). Thanks again,
Barry - N4BUQ
From: "Gary Follett via groups.io" <xntrick1948@...>
One test I have found to be useful is to plot output power on a given band versus position of the TX gain pot on the different bands. If you find that ?the saturation point of output (the point at which increasing the gain position produces no increase in output) versus position of the pot does not change as you go up in bands, then likely you have an alignment issue or a drive issue before the final mixer, because these earlier stages should produce more output than needed on the low bands to make up for poorer efficiency on the higher bands. In other words, you should be able to drive the heck out of the radio on 80 meters well before the saturation point of the TX gain pot.? Receiver gain issues track TX gain issues religiously. If TX gain is weak, receiver gain will be weak too. Gary W0DVN On Apr 28, 2025, at 7:44?PM, Ham Radio via groups.io <bernard.murphy@...> wrote: Steve: I assume you meant AGC. ? I have a TR-4 that has the same issue. ? Fine on TX but low on RX. ? See attached file.
--
73, Bernie. VE3FWF
Real?radios glow in the dark
<TR-4-tubes-sensitivity.xls>
|
Re: TR-4 Decreased Sensitivity on High Bands
Steve:
Have you tried cleaning the bandswitch?
Barry:
I was not certain whether or not the radio ever worked properly for you. If a radio worked well, then failed, it would be highly unlikely for alignment to be an issue. However, if the radio has never worked properly for you, then alignment would seem to be a good thing to try.
Gary
W0DVN
toggle quoted message
Show quoted text
On Apr 30, 2025, at 3:42?PM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
I have at least one intermittent component, in addition to 15/10 deafness/low power out.
I found some sensitivity when moving the "tower" under the 6EJ7.? Resoldered everything around it and measured the resistors, which are "close enough".? Can only get around 50W out on 15, with 250 mA of current.? Could be soft finals.
The xtal oscillators have sufficient amplitude.? When the rig goes deaf, 20 and 80 are deaf, as well.
There's definitely more than one and probably more than two problems here and one is intermittent!
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Wednesday, April 30th, 2025 at 2:29 PM, n4buq <n4buq@...> wrote:
Hi Gary,
If there are problems with the radio, I'm curious why the recommendation is not to align it.? I realize that it's easy to misalign it but if the procedures in the manual are followed, then what harm is it to do that?? I understand that a properly adjusted coil/transformer is likely never to go very far out of adjustment on its own but it's also difficult to know whether someone has golden-screwdrivered the rig as well.
Just curious.
Thanks, Barry - N4BUQ
That leaves the RF coils as suspect. While I generally do not recommend aligning a radio that once worked and now does not work, in this case you can pick a band that produces some measurable output and adjust the RF coils just a little, keeping track of how much you moved them. Any properly aligned coil should show a drop in output either side of the starting position.?
If you have a piece of brass and a piece of ferrite that will?fit into the adjustment holes, you can insert these into the coils without moving the coil slugs themselves. Inserting the brass will rise the tuned circuit frequency, inserting ferrite will lower that resonant frequency, performing the same test without physically moving the coil slugs¡ Insertion of either should reduce output of the radio if it is properly aligned already. I have a tool for this purpose but that does you little good, sorry. Gary W0DVN On Apr 29, 2025, at 10:33?AM, n4buq <n4buq@...> wrote: Two minor clarifications: The cap across the neutralizing variable cap allows me to set a proper null so that the variable cap can swing through that at about the point where the rotor is meshed approximately half-way (it wouldn't do that with the original cap). The loading equipment for the injection coupler alignment is called an "alignment load", not necessarily a "dummy load" as I referred to it and I didn't want to cause confusion with the antenna dummy load (and I still wonder about the etymology of that phrase). Gary, This morning, as I tuned up (into a dummy load) across all bands and I noticed that the XMTR GAIN seems to saturate at about the same point for all bands.? I seem to recall that a few weeks ago (before I started touching up the alignment points), I could get a LOT more gain out of the lower bands. The only component work I've done is to replace the cap across the PA neutralizing cap and have that so I can minimize the spurious oscillations with the appropriate power peak at the valley (dip) of the plate tuning cap rotation.? I also replaced the cathode resistors with new 15R 1W metal film caps as the originals were out of spec and were not well-matched. Maybe I've botched the alignment(s) and, perhaps, I need to revisit those.? Disappointing as I'd hoped to make things better and apparently that's not the case but I don't yet know what I might have done wrong (yes, I did use the designated dummy load when tweaking the injection couplers which I know is essential to getting those correct). Thanks again,
Barry - N4BUQ
From: "Gary Follett via groups.io" <xntrick1948@...>
One test I have found to be useful is to plot output power on a given band versus position of the TX gain pot on the different bands. If you find that ?the saturation point of output (the point at which increasing the gain position produces no increase in output) versus position of the pot does not change as you go up in bands, then likely you have an alignment issue or a drive issue before the final mixer, because these earlier stages should produce more output than needed on the low bands to make up for poorer efficiency on the higher bands. In other words, you should be able to drive the heck out of the radio on 80 meters well before the saturation point of the TX gain pot.? Receiver gain issues track TX gain issues religiously. If TX gain is weak, receiver gain will be weak too. Gary W0DVN On Apr 28, 2025, at 7:44?PM, Ham Radio via groups.io <bernard.murphy@...> wrote: Steve: I assume you meant AGC. ? I have a TR-4 that has the same issue. ? Fine on TX but low on RX. ? See attached file.
--
73, Bernie. VE3FWF
Real?radios glow in the dark
<TR-4-tubes-sensitivity.xls>
|
Re: TR-4 Decreased Sensitivity on High Bands
I have at least one intermittent component, in addition to 15/10 deafness/low power out.
I found some sensitivity when moving the "tower" under the 6EJ7.? Resoldered everything around it and measured the resistors, which are "close enough".? Can only get around 50W out on 15, with 250 mA of current.? Could be soft finals.
The xtal oscillators have sufficient amplitude.? When the rig goes deaf, 20 and 80 are deaf, as well.
There's definitely more than one and probably more than two problems here and one is intermittent!
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Wednesday, April 30th, 2025 at 2:29 PM, n4buq <n4buq@...> wrote:
Hi Gary,
If there are problems with the radio, I'm curious why the recommendation is not to align it.? I realize that it's easy to misalign it but if the procedures in the manual are followed, then what harm is it to do that?? I understand that a properly adjusted coil/transformer is likely never to go very far out of adjustment on its own but it's also difficult to know whether someone has golden-screwdrivered the rig as well.
Just curious.
Thanks, Barry - N4BUQ
That leaves the RF coils as suspect. While I generally do not recommend aligning a radio that once worked and now does not work, in this case you can pick a band that produces some measurable output and adjust the RF coils just a little, keeping track of how much you moved them. Any properly aligned coil should show a drop in output either side of the starting position.?
If you have a piece of brass and a piece of ferrite that will?fit into the adjustment holes, you can insert these into the coils without moving the coil slugs themselves. Inserting the brass will rise the tuned circuit frequency, inserting ferrite will lower that resonant frequency, performing the same test without physically moving the coil slugs¡ Insertion of either should reduce output of the radio if it is properly aligned already. I have a tool for this purpose but that does you little good, sorry. Gary W0DVN On Apr 29, 2025, at 10:33?AM, n4buq <n4buq@...> wrote: Two minor clarifications: The cap across the neutralizing variable cap allows me to set a proper null so that the variable cap can swing through that at about the point where the rotor is meshed approximately half-way (it wouldn't do that with the original cap). The loading equipment for the injection coupler alignment is called an "alignment load", not necessarily a "dummy load" as I referred to it and I didn't want to cause confusion with the antenna dummy load (and I still wonder about the etymology of that phrase). Gary, This morning, as I tuned up (into a dummy load) across all bands and I noticed that the XMTR GAIN seems to saturate at about the same point for all bands.? I seem to recall that a few weeks ago (before I started touching up the alignment points), I could get a LOT more gain out of the lower bands. The only component work I've done is to replace the cap across the PA neutralizing cap and have that so I can minimize the spurious oscillations with the appropriate power peak at the valley (dip) of the plate tuning cap rotation.? I also replaced the cathode resistors with new 15R 1W metal film caps as the originals were out of spec and were not well-matched. Maybe I've botched the alignment(s) and, perhaps, I need to revisit those.? Disappointing as I'd hoped to make things better and apparently that's not the case but I don't yet know what I might have done wrong (yes, I did use the designated dummy load when tweaking the injection couplers which I know is essential to getting those correct). Thanks again,
Barry - N4BUQ
From: "Gary Follett via groups.io" <xntrick1948@...>
One test I have found to be useful is to plot output power on a given band versus position of the TX gain pot on the different bands. If you find that ?the saturation point of output (the point at which increasing the gain position produces no increase in output) versus position of the pot does not change as you go up in bands, then likely you have an alignment issue or a drive issue before the final mixer, because these earlier stages should produce more output than needed on the low bands to make up for poorer efficiency on the higher bands. In other words, you should be able to drive the heck out of the radio on 80 meters well before the saturation point of the TX gain pot.? Receiver gain issues track TX gain issues religiously. If TX gain is weak, receiver gain will be weak too. Gary W0DVN On Apr 28, 2025, at 7:44?PM, Ham Radio via groups.io <bernard.murphy@...> wrote: Steve: I assume you meant AGC. ? I have a TR-4 that has the same issue. ? Fine on TX but low on RX. ? See attached file.
--
73, Bernie. VE3FWF
Real?radios glow in the dark
<TR-4-tubes-sensitivity.xls>
|
Re: TR-4 Decreased Sensitivity on High Bands
Hi Gary,
If there are problems with the radio, I'm curious why the recommendation is not to align it.? I realize that it's easy to misalign it but if the procedures in the manual are followed, then what harm is it to do that?? I understand that a properly adjusted coil/transformer is likely never to go very far out of adjustment on its own but it's also difficult to know whether someone has golden-screwdrivered the rig as well.
Just curious.
Thanks, Barry - N4BUQ
That leaves the RF coils as suspect. While I generally do not recommend aligning a radio that once worked and now does not work, in this case you can pick a band that produces some measurable output and adjust the RF coils just a little, keeping track of how much you moved them. Any properly aligned coil should show a drop in output either side of the starting position.?
If you have a piece of brass and a piece of ferrite that will?fit into the adjustment holes, you can insert these into the coils without moving the coil slugs themselves. Inserting the brass will rise the tuned circuit frequency, inserting ferrite will lower that resonant frequency, performing the same test without physically moving the coil slugs¡ Insertion of either should reduce output of the radio if it is properly aligned already. I have a tool for this purpose but that does you little good, sorry. Gary W0DVN On Apr 29, 2025, at 10:33?AM, n4buq <n4buq@...> wrote: Two minor clarifications: The cap across the neutralizing variable cap allows me to set a proper null so that the variable cap can swing through that at about the point where the rotor is meshed approximately half-way (it wouldn't do that with the original cap). The loading equipment for the injection coupler alignment is called an "alignment load", not necessarily a "dummy load" as I referred to it and I didn't want to cause confusion with the antenna dummy load (and I still wonder about the etymology of that phrase). Gary, This morning, as I tuned up (into a dummy load) across all bands and I noticed that the XMTR GAIN seems to saturate at about the same point for all bands.? I seem to recall that a few weeks ago (before I started touching up the alignment points), I could get a LOT more gain out of the lower bands. The only component work I've done is to replace the cap across the PA neutralizing cap and have that so I can minimize the spurious oscillations with the appropriate power peak at the valley (dip) of the plate tuning cap rotation.? I also replaced the cathode resistors with new 15R 1W metal film caps as the originals were out of spec and were not well-matched. Maybe I've botched the alignment(s) and, perhaps, I need to revisit those.? Disappointing as I'd hoped to make things better and apparently that's not the case but I don't yet know what I might have done wrong (yes, I did use the designated dummy load when tweaking the injection couplers which I know is essential to getting those correct). Thanks again,
Barry - N4BUQ
From: "Gary Follett via groups.io" <xntrick1948@...>
One test I have found to be useful is to plot output power on a given band versus position of the TX gain pot on the different bands. If you find that ?the saturation point of output (the point at which increasing the gain position produces no increase in output) versus position of the pot does not change as you go up in bands, then likely you have an alignment issue or a drive issue before the final mixer, because these earlier stages should produce more output than needed on the low bands to make up for poorer efficiency on the higher bands. In other words, you should be able to drive the heck out of the radio on 80 meters well before the saturation point of the TX gain pot.? Receiver gain issues track TX gain issues religiously. If TX gain is weak, receiver gain will be weak too. Gary W0DVN On Apr 28, 2025, at 7:44?PM, Ham Radio via groups.io <bernard.murphy@...> wrote: Steve: I assume you meant AGC. ? I have a TR-4 that has the same issue. ? Fine on TX but low on RX. ? See attached file.
--
73, Bernie. VE3FWF
Real?radios glow in the dark
<TR-4-tubes-sensitivity.xls>
|
Re: Another TR7 Journey begins
I did try using the low current pin and ground but that was with a separate PS, not the PS7 and the rig would not come on.? Should have used the PS7 I guess but the high current tap was easy enough to unsolder and I'll likely be taking the entire power module out anyway.? ?Guess I'll have to take the LPF module out again - hopefully without having to unsolder any wires - and figure out what the deal is with the 40M issue.
?
If I had any idea how challenging this rig would be to get going I would never have bought it lol.? And I really wish I had not sent it to a certain long time Drake tech who sent it back in worse shape telling me it was unrepairable.? Which cost me about $200 with shipping and his fee.? I'm to the point of selling it as is or trying to find somebody else who is a trusted Drake tech to look at it.
?
73, Bill NZ0T
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Thank you to all of you that have replied so far on this matter.? As I noted in my post, the replacement units as pictured by the different suppliers are identical to the module in the repeater which I believe is the one that has been in the repeater since manufacture.? It does not have an Icom logo on it, just the part number; what I believe is the production date and lot code as well as the Mitsubishi tri diamond trademark.? All sources state that the unit is new and not rebuilt which I don't think can be done based on the appearance of the module.
Ron, wa7gfe
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You know the bogus parts also say Icom, right?
A supplier like RF Parts is very trustworthy, obviously, but if the same part can be ordered from Icom, maybe just to be sure of getting a good part you buy it from Icom (of course, that assumes Icom's price is competitive, not a multiple of the RF Parts price).
For me, restoring an IC-2100h isn't worth $97.91, but to keep an Icom repeater on the air, that could be a reasonable investment.
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On Apr 30, 2025, at 01:43, Jahman N5ASE via groups.io <jah@...> wrote:
? See:??
Seems it's now the?$97.91 question.
73 de Andrew/N5ASE This is a bit off topic in some ways, in others it's something we have tossed around recently.
?
I have an Icom repeater that appears to have a failed PA module, it draws 10 amps and has an output of 1 watt.? It's a Mitsubishi RA55H4047M.? I have talked to Icom, they have the part in stock for about $120.? I have looked on line and I find this unit listed in many places other than Digikey, Mauser or Newark (They don't carry it).? The images of the units all look identical including 'Japan" printed on the units as compared to the unit in the repeater but all sources that I can find seem to be coming from Asia, specifically China at price points between $38 and $66.
?
The $64,000 question of course is do I risk one of these alleged "Genuine Mitsubishi" units or bite the bullet with Icom?
?
73, Ron
wa7gfe
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Jim Shorney
Ron Magnus