Re: Replaced T-4 Finals Resistors, Big Difference
Steve wrote "I sometimes remove the screws holding the board to the chassis. I can move the board enough to replace components. "
?
That's what I had to do. All I had on hand were 1/2W resistors and the leads were too fat to fit in the holes, so I had to hit Harbor Freight to get a set of dental picks with 90 degree hooks that I could use to ream out the holes. So tedious. Transmitter actually does work better now as I have access to the entire range of the gain control vs. the final 5 degrees as before. All the resistors (and more) that Peter had called out were all way out of spec.?
?
Someone wrote in overnight and requested pictures of the resistor mods in the final stage that I did. I hesitate to do this as I did these mods for me and my own OCD about over-engineering, versus some of the accepted best practices that I've read on this site.?
Here is the mod that I did for the meter shunt resistor R59. Not only could I not accurately set my bias due to the "non-zero" meter on the T-4XC, but the resistor was reading way out of spec (again!) and therefore giving inaccurate iP readings. I decided to ridiculously over-spec it to 25W, mostly so I could get a quality 1% resistor? on there that I could branch off leads to binding posts. That way I could measure the drop across the 3.3 ohm resistor externally, and accurately set bias. I fabricated a little copper clip to hold the resistor. At full plate current this resistor should only dissipate .4W so heat should not be an issue, but I'm covered.?
?
I also didn't like the fact that the cathode resistors were being used as "fuses" and seemed vulnerable to heat stress. So I set up some 5W units to heat-sink against the chassis.?
?
So far, so good. TX a lot more stable and the output difference is noticeable. Again, mods are very personal and not everyone's cup of tea.?
?
Thanks Steve & Peter for your suggestions & advice.?
--
Craig/W8CS
Greenville, SC
|
Re: Another TR7 Journey begins
If you look at wiring of the power connector you will see two pins for the +13v. One pin is dedicated to the high current PA load and the other pin powers everything else in the radio Simple put voltage to the pin that powers the rest of the radio only. On Sat, 12 Apr 2025 05:55:17 -0700 "Bill NZ0T via groups.io" <nz0tham@...> wrote: As expected the issue is still there with the DR7 installed. So it's time to check out the TX problem.? I need to figure out what I need to disconnect to isolate the TX module so I can make sure the RX is working OK before I tackle the TX module.? Time to watch some more DL7MAJ videos! -- 73 -Jim NU0C
|
Re: Bezel for PLJ 6LED display?
I'll be getting my hands on an R-4B soon that has a digital display.? I'll trade it for a good PTO that has a nice, clear frequency disc.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Saturday, April 12th, 2025 at 12:20 PM, Mark - WB0IQK <mgilger@...> wrote:
If you leave the front panel original, only a very small portion of the first and last digits will be partially hidden if you're looking at the radio head-on. If you look at the radio slightly from the left or right, the missing part of the digit will become viewable.? I chose not to modify the front panel as I wanted to keep it original in case I wanted to refer back to the analog dial. It's been over 10 years since I wrote the article, and both R4Cs still have the displays installed.?
?
If you have not seen the article, the following link will take you to it.??
?
?
Mark, WB0IQK
|
Re: Replaced T-4 Finals Resistors, Big Difference
Barry, be aware that modern metal film resistors are quite a bit smaller, physically.? They are well capable of their 1W rating but they look almost as small as 1/2W CC resistors.
I've replaced the cathode resistors in several rigs already with the new metal film and they work great.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Saturday, April 12th, 2025 at 11:15 AM, n4buq <n4buq@...> wrote:
I received my TR-4 manual from K4OAH last night and the cathode resistors are clearly marked as 1W in the schematic as well as the parts list.? The schematic I found on line did not show that "1W" so I wasn't sure.
I'll definitely be getting 1W resistors.? Thanks for the info!
Barry - N4BUQ For whatever reason, I was thinking the "standard, basic" carbon composition resistors that are everywhere in vintage gear were 1/4W but instead I think they're 1/2W.? The typical schematic would read "unless otherwise stated, resistors are 1/2W", etc., and I was thinking those were stated as 1/4W which would have been pretty atypical back then.? Anyway, I got my 1/4W and 1/2W sizes confused in my head. Apparently the ones in my TR-4 are 1/2W (measured at 0.135" diameter x 0.4" long) and I wonder why Drake did that if they're supposed to be 1W.? These appear to be factory originals. Thanks, Barry - N4BUQ Barry: On the PA cathode resistors, note they are 1 watt resistors in all the 4-line gear.? I've been using?film resistors for years without issue.?? 73 PS
I just checked the cathode resistors in my TR-4 and they probably should be replaced.? They're not equal and are 20% to 40% over 15 ohms.? Is it recommended to stick with carbon comps for those or will film resistors be okay?? If I remember correctly, these should be kept at 1/4W but not 100% sure on that either. Thanks for the reminder! Barry - N4BUQ Craig: Congrats on the resistors already checked and replaced.? Those parts are standard checks and "replace as required" for me, which in those particular cases is often. If you still have the T-4XC open, check the voltage on pin 1 of V-9a and pin 6 of V-9b.? If voltage is low, check resistors R-91 and R-81 (you'll need K4OAH's Service manual to find these easily) as I have found these tend to drift high as well,?especially R-91.? I have seen voltage on pin 1 as low as 68 VDC before changing R-91. 73, Peter VE7PS
On Fri, Apr 11, 2025 at 6:08?AM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Yep, those resistors are important!? My TR-4Cw RIT has excellent cosmetics and the cathode resistors were all 17.5 to 18.5. Screen resistors were around 80. Output on 40m went from 150 to 180.?
I¡¯ll now be reviewing all of my transmitters and replacing anything out of tolerance.? Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 10, 2025 at 15:14, Craig W8CS via < craig_severson@...> wrote:
I'm not the first to have done this, just reporting this to help if anyone is on the fence.?
?
I noticed some poor performance on my T-4XC that I pulled out of mothballs this year after a long siesta.?
?
Did the heathkit shop AC-4 upgrade, no difference in output, more of a preventative thing with 48 year old caps.?
?
Started poking around the finals section and noticed that the cathode resistors were 17.2 and 19.3 ohms, pretty out of spec for 15 ohm resistors. This week I got around to looking at the rest of the circuit including screen, screen supply, and meter shunt resistors.?
- R49 2W 1.5Kohm was heat-swollen and running 1600 ohms
- R50/R51 screen resistors (68 ohm) were measuring 73/76 ohms
- R59 meter shunt resistor (3.3 ohm) was measuring 4.5 ohms
Replaced all of these with upgraded/over-spec components and WOW what a difference. Easily hits 100W output on 10M, 150W+ on lower bands.?
No, I'm not going to run this unit at those numbers but nice to see the potential. And this is with what I consider to be "soft" final tubes.?
?
Also installed a couple of binding posts on the rear panel which pigtail across the meter shunt resistor for easier bias set/checks.?
?
I could post pictures of the mods if anyone is curious.?
--
Craig/W8CS
Greenville, SC
|
Re: Bezel for PLJ 6LED display?
If you leave the front panel original, only a very small portion of the first and last digits will be partially hidden if you're looking at the radio head-on. If you look at the radio slightly from the left or right, the missing part of the digit will become viewable.? I chose not to modify the front panel as I wanted to keep it original in case I wanted to refer back to the analog dial. It's been over 10 years since I wrote the article, and both R4Cs still have the displays installed.?
?
If you have not seen the article, the following link will take you to it.??
?
?
Mark, WB0IQK
|
Re: Replaced T-4 Finals Resistors, Big Difference
I received my TR-4 manual from K4OAH last night and the cathode resistors are clearly marked as 1W in the schematic as well as the parts list.? The schematic I found on line did not show that "1W" so I wasn't sure.
I'll definitely be getting 1W resistors.? Thanks for the info!
Barry - N4BUQ
For whatever reason, I was thinking the "standard, basic" carbon composition resistors that are everywhere in vintage gear were 1/4W but instead I think they're 1/2W.? The typical schematic would read "unless otherwise stated, resistors are 1/2W", etc., and I was thinking those were stated as 1/4W which would have been pretty atypical back then.? Anyway, I got my 1/4W and 1/2W sizes confused in my head. Apparently the ones in my TR-4 are 1/2W (measured at 0.135" diameter x 0.4" long) and I wonder why Drake did that if they're supposed to be 1W.? These appear to be factory originals. Thanks, Barry - N4BUQ Barry: On the PA cathode resistors, note they are 1 watt resistors in all the 4-line gear.? I've been using?film resistors for years without issue.?? 73 PS
I just checked the cathode resistors in my TR-4 and they probably should be replaced.? They're not equal and are 20% to 40% over 15 ohms.? Is it recommended to stick with carbon comps for those or will film resistors be okay?? If I remember correctly, these should be kept at 1/4W but not 100% sure on that either. Thanks for the reminder! Barry - N4BUQ Craig: Congrats on the resistors already checked and replaced.? Those parts are standard checks and "replace as required" for me, which in those particular cases is often. If you still have the T-4XC open, check the voltage on pin 1 of V-9a and pin 6 of V-9b.? If voltage is low, check resistors R-91 and R-81 (you'll need K4OAH's Service manual to find these easily) as I have found these tend to drift high as well,?especially R-91.? I have seen voltage on pin 1 as low as 68 VDC before changing R-91. 73, Peter VE7PS
On Fri, Apr 11, 2025 at 6:08?AM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Yep, those resistors are important!? My TR-4Cw RIT has excellent cosmetics and the cathode resistors were all 17.5 to 18.5. Screen resistors were around 80. Output on 40m went from 150 to 180.?
I¡¯ll now be reviewing all of my transmitters and replacing anything out of tolerance.? Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 10, 2025 at 15:14, Craig W8CS via < craig_severson@...> wrote:
I'm not the first to have done this, just reporting this to help if anyone is on the fence.?
?
I noticed some poor performance on my T-4XC that I pulled out of mothballs this year after a long siesta.?
?
Did the heathkit shop AC-4 upgrade, no difference in output, more of a preventative thing with 48 year old caps.?
?
Started poking around the finals section and noticed that the cathode resistors were 17.2 and 19.3 ohms, pretty out of spec for 15 ohm resistors. This week I got around to looking at the rest of the circuit including screen, screen supply, and meter shunt resistors.?
- R49 2W 1.5Kohm was heat-swollen and running 1600 ohms
- R50/R51 screen resistors (68 ohm) were measuring 73/76 ohms
- R59 meter shunt resistor (3.3 ohm) was measuring 4.5 ohms
Replaced all of these with upgraded/over-spec components and WOW what a difference. Easily hits 100W output on 10M, 150W+ on lower bands.?
No, I'm not going to run this unit at those numbers but nice to see the potential. And this is with what I consider to be "soft" final tubes.?
?
Also installed a couple of binding posts on the rear panel which pigtail across the meter shunt resistor for easier bias set/checks.?
?
I could post pictures of the mods if anyone is curious.?
--
Craig/W8CS
Greenville, SC
|
Re: TR4310 HF Transceiver
Evan:
I should use the RIT more often., though I think we may have talked about that feature a while back.? I'll check mine later today....still on java cup #1!
73 PS??
There is a possible differance among the TR-7/TR-7A, the RV-75, and the 4310.? My 4310 has a feature not present in the other gear. ? When using the RIT, if the main PTO is changed it automatically turns off the RIT.? I don't know if this is the case for all 4310s or not.
Evan, K9SQG
On Friday, April 11, 2025 at 11:02:18 PM EDT, Gary Follett via <xntrick1948= [email protected]> wrote:
The TR4310 is the same as a TR7 in virtually every way. It uses a PTO as a reference for the two VCO¡¯s, one for the bands below 14 MHz and a second one for the higher bands. The chirping you are hearing is the VCO trying to seek a lock.
You should also see the digital frequency display ramping up as the radio goes through this process. First question-does it do this on low bands and high bands as well?
If you have an oscilloscope, you can have a look at the PTO output to see if it is missing when the radio is cold. No amount of drift in the PTO will cause the lock-seeking condition you experience, so all you need to confirm is that the PTO signal is present. However, total absence of the PTO signal will produce the problem you are having.
The most common cause of synthesizer lock problems is the condition of the switches that control which PTO is in use (internal, RV7, RV75 etc.), and also the ¡°Fixed¡± switches. A quick spray with contact cleaner should fix this.
Also, the rotary switch that controls the AUX7 function can also cause the problem. Again, a spray with cleaner should tidy things up.
Whenever spraying a switch, immediately operate the switch through all positions quickly several times to complete the cleaning process.
Gary?
W0DVN ? Mark
Thank you so VERY much for the quick and detailed response.?
I will print your response out and go through one by one.?
B.r / Tilman SM0JZT
|
Re: Another TR7 Journey begins
As expected the issue is still there with the DR7 installed. So it's time to check out the TX problem.? I need to figure out what I need to disconnect to isolate the TX module so I can make sure the RX is working OK before I tackle the TX module.? Time to watch some more DL7MAJ videos!
?
73, Bill NZ0T
|
Re: Replaced T-4 Finals Resistors, Big Difference
I sometimes remove the screws holding the board to the chassis. I can move the board enough to replace components.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Apr 11, 2025 at 21:34, Craig W8CS via groups.io < craig_severson@...> wrote:
I have never had reason to dig into the ancillary PCBs in the bottom of the T4 chassis before. Honestly don't know how you extract anything from the bottom of those boards! Will try again tomorrow once I restore some patience.?
--
Craig/W8CS
Greenville, SC
|
Re: TR4310 HF Transceiver
There is a possible differance among the TR-7/TR-7A, the RV-75, and the 4310. ?My 4310 has a feature not present in the other gear. ? When using the RIT, if the main PTO is changed it automatically turns off the RIT. ?I don't know if this is the case for all 4310s or not.
Evan, K9SQG
The TR4310 is the same as a TR7 in virtually every way. It uses a PTO as a reference for the two VCO¡¯s, one for the bands below 14 MHz and a second one for the higher bands. The chirping you are hearing is the VCO trying to seek a lock.
You should also see the digital frequency display ramping up as the radio goes through this process. First question-does it do this on low bands and high bands as well?
If you have an oscilloscope, you can have a look at the PTO output to see if it is missing when the radio is cold. No amount of drift in the PTO will cause the lock-seeking condition you experience, so all you need to confirm is that the PTO signal is present. However, total absence of the PTO signal will produce the problem you are having.
The most common cause of synthesizer lock problems is the condition of the switches that control which PTO is in use (internal, RV7, RV75 etc.), and also the ¡°Fixed¡± switches. A quick spray with contact cleaner should fix this.
Also, the rotary switch that controls the AUX7 function can also cause the problem. Again, a spray with cleaner should tidy things up.
Whenever spraying a switch, immediately operate the switch through all positions quickly several times to complete the cleaning process.
Gary?
W0DVN
On Apr 11, 2025, at 4:59?AM, Tilman SM0JZT via groups.io <sm0jzt@...> wrote:
? Mark
Thank you so VERY much for the quick and detailed response.?
I will print your response out and go through one by one.?
B.r / Tilman SM0JZT
|
Re: TR4310 HF Transceiver
If the RIT circuit is the same as the TR7 that shouldn't happen. The switch is DPDT and one half fires the lamp when pushed in. The other half applies +10 to either the RIT or /RIT control signal on the PBT/REF board. That's it. The rest is simple analog voltage steering through a 4016 analog switch IC. No digital involved. OTOH if they did something different involving the synthesized VRTO then all bets are off. It may be a feature or a bug.... On Fri, 11 Apr 2025 08:42:48 -0700 "VE7PS via groups.io" <ve7ps@...> wrote: Tilman...congrats on the TR-4310.
Mine also has the "RIT ON at startup" issue, and I believe others do too.
I gave up trying to find why, but then I am not a digital guy at all,
Maybe Mark can set us straight on this one?
Every few years I need to pull it out and clean all the Molex connectors,
same as the TR-7's. So far that process has solved any other problems that
have cropped up.
73
Peter
VE7PS -- 73 -Jim NU0C
|
Re: TR4310 HF Transceiver
The TR4310 is the same as a TR7 in virtually every way. It uses a PTO as a reference for the two VCO¡¯s, one for the bands below 14 MHz and a second one for the higher bands. The chirping you are hearing is the VCO trying to seek a lock.
You should also see the digital frequency display ramping up as the radio goes through this process. First question-does it do this on low bands and high bands as well?
If you have an oscilloscope, you can have a look at the PTO output to see if it is missing when the radio is cold. No amount of drift in the PTO will cause the lock-seeking condition you experience, so all you need to confirm is that the PTO signal is present. However, total absence of the PTO signal will produce the problem you are having.
The most common cause of synthesizer lock problems is the condition of the switches that control which PTO is in use (internal, RV7, RV75 etc.), and also the ¡°Fixed¡± switches. A quick spray with contact cleaner should fix this.
Also, the rotary switch that controls the AUX7 function can also cause the problem. Again, a spray with cleaner should tidy things up.
Whenever spraying a switch, immediately operate the switch through all positions quickly several times to complete the cleaning process.
Gary?
W0DVN
toggle quoted message
Show quoted text
On Apr 11, 2025, at 4:59?AM, Tilman SM0JZT via groups.io <sm0jzt@...> wrote:
? Mark
Thank you so VERY much for the quick and detailed response.?
I will print your response out and go through one by one.?
B.r / Tilman SM0JZT
|
Re: Ordering K4OAH Manuals
I got the link in 18 minutes tonight (a Friday night)!!
Barry - N4BUQ
I ordered the C-line tonight via paypal and had the email in my inbox within an hour. Pretty cool legacy.?
--
Craig/W8CS
Greenville, SC
|
Re: Ordering K4OAH Manuals
Garey lived in Huntsville, AL, in the early 1960s.? He used to talk about getting his first 2-B from one of the local places.? I've lived here since about 1956 and I really wish I'd met him but I think he moved before I became interested in ham radio in my mid teen years.
Now to get that manual ordered!
Thanks, Barry - N4BUQ
I ordered the C-line tonight via paypal and had the email in my inbox within an hour. Pretty cool legacy.?
--
Craig/W8CS
Greenville, SC
|
Re: Ordering K4OAH Manuals
I ordered the C-line tonight via paypal and had the email in my inbox within an hour. Pretty cool legacy.?
--
Craig/W8CS
Greenville, SC
|
Re: Replaced T-4 Finals Resistors, Big Difference
I have never had reason to dig into the ancillary PCBs in the bottom of the T4 chassis before. Honestly don't know how you extract anything from the bottom of those boards! Will try again tomorrow once I restore some patience.?
--
Craig/W8CS
Greenville, SC
|
toggle quoted message
Show quoted text
On Sat, Mar 29, 2025 at 7:47 PM, K6OXN Bob via groups.io <bobk6oxn@...> wrote: [Edited Message Follows]
Have now switched to another old standby a D104 without amp and it sounds great on the air.? I record from an SDR site and then listen. Very few winks of the ALC and getting a very good output from the L7
|
Re: Bezel for PLJ 6LED display?
Floyd, ? If you have a 3D Printer you can print one similar to the pic below.? That particular one is for the PLJ8LED version, which I have. Not a Bezel, but certainly a case designed for the device.? I think I found the files on Thingiverse. I just went and did a google search and there are a few options specifically for the PLJ6LED. ? Thank you, Mike W5CUL ? 
? ?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]> On Behalf Of Floyd - K8AC via groups.io
Sent: Thursday, April 10, 2025 2:55 PM
To: [email protected]
Subject: [DRAKE-RADIO] Bezel for PLJ 6LED display?? I've been using one of the PLJ 6LED counter modules in an external housing for digital frequency readout for my R4C.? I'd like to mount the display inside the existing dial window on the R4C, but the window isn't really wide enough to view all the digits.? So, would like to modify the width of the window but would need a bezel to give it the desired finished look.? I've searched the usual sources for an appropriate bezel, but haven't come up with anything that will fit properly.? I wonder if anyone else has located one???
|
Re: Ordering K4OAH Manuals
Thanks, guys. Yes, I knew she was managing the orders now. Now that I'm working on my TR-4, I could use one of his manuals. I see where the Drake4@mindspring address is just for more information and the k4oah@mindspring is for PayPal. I think I'm good now.
Thanks again,
Barry - N4BUQ
toggle quoted message
Show quoted text
----- Original Message ----- From: "Steven KW4H via groups.io" <reedsteve@...>
To: "DRAKE-RADIO" <[email protected]>
Sent: Friday, April 11, 2025 5:18:18 PM
Subject: Re: [DRAKE-RADIO] Ordering K4OAH Manuals Yes. Send a PayPal payment with a note on what you're ordering, and you will
receive a download link. His wife still manages the orders.
73 - Steve, KW4H
On Friday, April 11th, 2025 at 5:11 PM, n4buq <n4buq@...> wrote:
I've been to the K4OAH site but it's slightly unclear how to order. Is it
sufficient to send the funds (PayPal, etc.) with a note stating which manual
one is ordering? I bought one before Garey's passing but not since so I want to
make sure how to do that now. I presume I could send an email to the mindspring
address on the K4OAH site as well?
Thanks,
Barry - N4BUQ
|
Re: Ordering K4OAH Manuals
Yes. Send a PayPal payment with a note on what you're ordering, and you will receive a download link. His wife still manages the orders.
73 - Steve, KW4H
toggle quoted message
Show quoted text
On Friday, April 11th, 2025 at 5:11 PM, n4buq <n4buq@...> wrote:
I've been to the K4OAH site but it's slightly unclear how to order. Is it sufficient to send the funds (PayPal, etc.) with a note stating which manual one is ordering? I bought one before Garey's passing but not since so I want to make sure how to do that now. I presume I could send an email to the mindspring address on the K4OAH site as well?
Thanks,
Barry - N4BUQ
|
Craig W8CS
Jim Shorney