Re: Replaced T-4 Finals Resistors, Big Difference
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 groups.io < 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: Another TR7 Journey begins
Thanks Jim,
?
No I didn't have the DR& installed, dumb of me.? I'll install it and see what happens but I'm sure as you said that there's an issue with drivers/finals or bias.
?
Someday this rig will work!
?
73, Bill NZ0T
|
Re: TR4310 HF Transceiver
That's probably just a dirty pushbutton. I would check the +24V source on the PS board. You hay have a failing capacitor. On Fri, 11 Apr 2025 04:03:42 -0700 "Tilman SM0JZT via groups.io" <sm0jzt@...> wrote: [Edited Message Follows]
Mark
Thank you so VERY much for the quick and detailed response.
I will print your response out and go through one by one.
Forgot. I found at "cold start" that the RIT-lamp is lit...... When hitting the RIT-button it disappears. Does that ring sort of bell ?
B.r / Tilman SM0JZT
-- 73 -Jim NU0C
|
Re: TR4310 HF Transceiver
Mark
Thank you so VERY much for the quick and detailed response.?
I will print your response out and go through one by one.?
Forgot. I found at "cold start" that the RIT-lamp is lit...... When hitting the RIT-button it disappears. Does that ring sort of bell ?
B.r / Tilman SM0JZT
|
Re: TR4310 HF Transceiver
Tilman,
?
Sorry to hear you have trouble with your TR4310.
?
As you perhaps know, there are two synthesisers in the '4310:
?
(1) The 'Variable Rate Tuning Oscillator' (VRTO) synthesiser system (the one for the front panel tuning / VFO knob) provides the same 5.05 - 5.55 MHz output signal for each and every 500 kHz frequency range that the transceiver operates on. VRTO is just a synthesised (= more stable) version of the free-running PTO in other Drake radio, like the TR7. I would not expect this oscillator to be the cause of your issue. You can confirm this by tuning the VFO knob from one end to the other on any frequency range apart from the ones you have a problem with. If tuning is normal and there are no chirps, the VRTO is good! It's important that the VRTO output is good, as it is used as a (variable frequency) reference oscillator by the major loop synthesiser 2., below.
?
(2) The 'frequency range' (major loop) synthesiser - essentially the same as the one in a TR7. This provides the oscillator injection to the Up Converter (first mixer) at (RF signal frequency + 48 MHz). Indirectly, I think you problem may lie here.
The flow of data for programming the major loop synthesiser starts with the RANGE (band) switch. Data from the range switch provides address data to a PROM (U201) on the Digital Control Board. 8-bit output data from this PROM is sent to the VRTO Digital Board and from there to the Translator Board. Each 8-bit code represents a different 0.5 MHz wide frequency range.
?
For each position of the RANGE switch, the transceiver has a default / cold-starting frequency range. The major loop synthesiser programming data for these starting frequency ranges are what U201 contains. For a standard TR4310 fitted with the U201 'Marine' band PROM, when the RANGE switch is set to 10 - 15 MHz, the startup range is 12.5 MHz (12.5 - 13.0 MHz).
?
For each of the startup frequency ranges, circuitry on the VRTO Digital Board allows the user to modify the synthesiser programming data sent to the Translator Board by means of pressing the 'UP' and 'DOWN' buttons on the front panel. So, in the case of the 10 - 15 MHz range, you can manually select any of the 0.5 MHz wide ranges between those limits.
?
[If there is an AUX7 card present in the transceiver, data coming from any modules fitted to the AUX7 can override all of this to and force synthesiser programming data sent to the major loop (Translator Board) to operate on particular ranges, regardless of the position of the RANGE switch, which you have to set manually with the 'SET BAND' light as you guide to when it is correctly set, or not].
?
?
So, my hypothesis is that your '4310 may have some bad data / data bits being sent from the VRTO Digital Board to the Translator Board for two positions of the RANGE switch. If the data is bad, the VCO on the Translator Board will be confused as to what frequency it should produce and, as a result, the major loop will become unlocked.
?
My first questions:
1. When starting from cold, with the RANGE switch set to 10 - 15 MHz position, does the transceiver power up on 12.750 MHz? Without touching any controls, does it start 'chirping' on that frequency?
2. When starting from cold, with the RANGE switch set to 15 - 22 MHz position, does the transceiver power up on 16.750 MHz? Without touching any controls, does it start 'chirping' on that frequency?
3. Does your radio have an AUX7 card fitted with a module programmed somewhere between 12.5 and 15.5 MHz? (I am lucky, my radio has one for 14.0 MHz / 20 m band!) If it does, is there any 'chirping' when using the AUX 7 to set the frequency range?
?
?
Before suspecting any more complex electronic fault, I would open the transceiver up and:
1. Clean the contacts on the RANGE switch that are responsible for providing data to the Digital Control Board (see manual for which wafers).
?
2. Clean the UP and DOWN switches.
?
3. Clean the Molex connectors on the Digital Control Board, VRTO Digital Board (large and small connectors) and Translator Board. Also their corresponding connectors on the parent board.
Be very careful when pulling and re-installing boards, especially the VRTO Digital Board (there is a procedure in the manual for this one), as it's easy to bend pins on the connectors / get them mis-aligned. You do not need to hinge the front panel of the transceiver to remove / install the VRTO Digital Board if you are super careful.
The VRTO Digital Board is notorious for having dry joints on the pins of the large Molex connectors. If any look suspect when you have the board removed, re-flow the solder, taking care not to melt the plastic housing of the connector.
?
Please report back. I hope you did not fall asleep reading my explanation!
?
Regards,
?
Mark, G4FPH.
|
Re: TR4310 HF Transceiver
Hi there guys (and gals)
I have a TR4310 that I recently obtained.?
Seems to be working ok except for the following that puzzles me quiet a bit:
When "warming up" straight after a "cold start" one can hear a "chirping" in the speaker. Like the VFO-circuitry is trying to lock. After a while it settles and the radio is usable.?
I can receive and transmit on all frequencies except for between around 12.5 and 15.5 Mhz. There it seems like to VFO (synthesizer ) does not want to lock and therefore the radio does not want to go into TX ( nor receive ).
?
Looks like there is something wrong with the VFO-circuitry
Im somewhat stuck with where to look for the fault with troubleshooting.?
Any help is much appreciated. /? ?Tilman SM0JZT
|
Re: OFF-TOPIC: Finding nearby US hams
Bill,
Here is a real link:
-Tom, AG9X
On Thu, Apr 10, 2025 at 7:45?PM Bill Blodgett. AI5RP via <whb5k= [email protected]> wrote: Tom,
Neither the links work, nor are there any searches available for amateur operators.? Please provide additional information.
73, Bill W5WHB ++++++++++++++++ Bill Blodgett Arlington, Texas
|
Re: OFF-TOPIC: Finding nearby US hams
Ken, Ed, Jim, Lawrence,
Thank you all for the list of alternative databases.
Jim, I appreciated the step by step instructions to the QRZ map.
These are fun to play with, especially when displayed on a map. Each database has its own unique strengths.
73, Tom AG9X
|
I've posted recently about some problems I've had neutralizing the finals in my TR-4. I think in the last post I made about it, I stated that the original 12pF (C77) that's across the variable capacitor, C76, tested completely bad ("No, unknown, or damaged part"); however, it occurred to me that this tester (a "T7") isn't spec'd to test below 20pF so the original may still be good.
In any case, I ordered some replacements (a 10pF, a 12pF, and a 15pF) and they arrived today. I tried the 12pF and got basically the same results as the original (a semi-null with C76 fully open). I then decided to try a 2pF SM I happened to have and that gave me a semi-null with the plates fully closed so I figured the sweet-spot must be somewhere between those two values.
Since I didn't have anything on hand at around 7pF, I connected the 15pF and the 10pF in series to obtain 6pF across C76 and that gives me a null with the plates virtually at the half-way point so now I'm searching for a suitable capacitor in the 6pF range but I'm not finding anything.
Anyone know where I might find a suitable capacitor? If I can't find something, I may just stick with the two capacitors in series but I'm not very fond of a "flying splice" like that.
What I'm really wondering about is why this rig needs only half of the original value capacitor in that place. I know that Steve has mentioned a brand of tubes that apparently needs a little more capacitance but haven't heard anything about needing less and so I'm wondering what could be causing that. As far as I can tell, there are no other capacitors in parallel with those two but several other capacitors connected to that part of the circuit in one way or the other. Any suggestions as to anything I might look for or maybe I should just chalk it up to the rig being 60 years old and several factors could be at play because of aging parts.
Thanks,
Barry - N4BUQ
|
Re: OFF-TOPIC: Finding nearby US hams
Tom,
Neither the links work, nor are there any searches available for amateur operators. ?Please provide additional information.
73, Bill W5WHB ++++++++++++++++ Bill Blodgett Arlington, Texas
toggle quoted message
Show quoted text
On Apr 10, 2025, at 1:06?PM, Tom Evans via groups.io <Tom.AG9X@...> wrote:
? On a recent walk, I noticed a new vertical antenna a few blocks from me.? It had traps, so most likely a ham.
Back home, I was surprised to find has FCC license data organized by community.
To take a look, enter this in your favorite search engine and append a US city and state.
site: amateur radio licenses
Example: site: amateur radio licenses Montpelier, Vermont
73, Tom, AG9X
|
Re: OFF-TOPIC: Finding nearby US hams
Yet another resource. ?Change the zip code to meet your needs.?
?
https://haminfo.tetranz.com/map/z/46106
|
Re: OFF-TOPIC: Finding nearby US hams
You can also do this on qrz. Look up your callsign and then under the Detail tab click "Explore on HamGrid Maps" just below the map. It will show you nearby hams in your grid subsquare and you can select additional subsquares as needed. The exact locations are obscured, but close enough. you can pan/zoom/click as usual on interactive maps. On Thu, 10 Apr 2025 12:39:29 -0500 "Tom Evans via groups.io" <Tom.AG9X@...> wrote: To take a look, enter this in your favorite search engine and append a US
city and state. -- 73 -Jim NU0C
|
Re: Another TR7 Journey begins
If the heatsink is getting warm in RX that is a sign that you may have a leaky or shorted final or driver. The bias regulator circuit should also be checked. Did you mean that you did not have the DR7 board installed? You will have no frequency control unless you have a Jumper Board connected in its place but it would not cause PA overheating of fuse blowage. On Thu, 10 Apr 2025 08:55:06 -0700 "Bill NZ0T via groups.io" <nz0tham@...> wrote: Update and it ain't good.? I got the LPF put back in yesterday - soldering the wires back on was not as bad as I thought would be thankfully.? This morning I got the bandswitch rod back in and the bandswitching seems to be fine.? I re-installed all the boards with the exception of the digital, crossed my fingers and fired the TR& up.? Got lights for a second and then the PS7 blew.? After a short reset I tried again same result - dumb I know.? Finally I found that the rig would stay on on 10 meters only. There is audio, PBT works but I don't hear the calibrator or any other signals.? That's when I noticed the TX module heatsink was hot even though I see no RF output. So I quickly shut the rig off.
So I'm gonna step back until next week before I cause further damage to the rig.? My initial thoughts are that I wired the LPF incorrectly somehow but I was really careful making sure I documented by photo where they went and made sure I soldered them back in the correct? spots.? I checked again and they all look correct.? Maybe the LPF module has an issue and the weird mods were an attempt to repair it?? Maybe I didn't get one of the boards re-inserted correctly? Aaarghhh! -- 73 -Jim NU0C
|
Re: Bezel for PLJ 6LED display?
I just mounted mine in a digital alarm? clock case from Goodwill external to radio.
Larry
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???
?
73, Floyd - K8AC
?
?
?
?
?
?
?
?
?
?
?
|
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???
?
73, Floyd - K8AC
?
?
?
?
?
?
?
?
?
?
?
|
Re: OFF-TOPIC: Finding nearby US hams
QRZ allows you to do the same.?
You can search by name, address, county, etc..
Ed
KG5UN
|
Replaced T-4 Finals Resistors, Big Difference
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: OFF-TOPIC: Finding nearby US hams
Neat, thanks for sharing.
FYI, the ARRL has a license look-up tool that is also pretty useful (and is available to the public, no membership required):
?
toggle quoted message
Show quoted text
On Apr 10, 2025, at 12:39, Tom Evans via groups.io <Tom.AG9X@...> wrote:
? On a recent walk, I noticed a new vertical antenna a few blocks from me.? It had traps, so most likely a ham.
Back home, I was surprised to find has FCC license data organized by community.
To take a look, enter this in your favorite search engine and append a US city and state.
site: amateur radio licenses
Example: site: amateur radio licenses Montpelier, Vermont
73, Tom, AG9X
|
OFF-TOPIC: Finding nearby US hams
On a recent walk, I noticed a new vertical antenna a few blocks from me.? It had traps, so most likely a ham.
Back home, I was surprised to find has FCC license data organized by community.
To take a look, enter this in your favorite search engine and append a US city and state.
site: amateur radio licenses
Example: site: amateur radio licenses Montpelier, Vermont
73, Tom, AG9X
|
Re: Another TR7 Journey begins
Update and it ain't good.? I got the LPF put back in yesterday - soldering the wires back on was not as bad as I thought would be thankfully.? This morning I got the bandswitch rod back in and the bandswitching seems to be fine.? I re-installed all the boards with the exception of the digital, crossed my fingers and fired the TR& up.? Got lights for a second and then the PS7 blew.? After a short reset I tried again same result - dumb I know.? Finally I found that the rig would stay on on 10 meters only. There is audio, PBT works but I don't hear the calibrator or any other signals.? That's when I noticed the TX module heatsink was hot even though I see no RF output. So I quickly shut the rig off.
?
So I'm gonna step back until next week before I cause further damage to the rig.? My initial thoughts are that I wired the LPF incorrectly somehow but I was really careful making sure I documented by photo where they went and made sure I soldered them back in the correct? spots.? I checked again and they all look correct.? Maybe the LPF module has an issue and the weird mods were an attempt to repair it?? Maybe I didn't get one of the boards re-inserted correctly? Aaarghhh!
?
73, Bill NZ0T
|
Jim Shorney
Tilman SM0JZT
Floyd - K8AC
Ed KG5UN
Craig W8CS