Re: Tuning a pi-Network Output
This one has GE tubes.? Not sure if those are considered the "good" ones (like the Sylvanias) or if they need more capacitance.? Hopefully I'll get to the neutralization adjustment today or tomorrow.
Thanks, Barry - N4BUQ
From: "Steve Wedge, W1ES/4 via groups.io" <w1es@...>
To: "DRAKE-RADIO" <[email protected]>
Sent: Friday, April 4, 2025 7:17:29 AM
Subject: Re: [DRAKE-RADIO] Tuning a pi-Network Output
IIRC, you need a slightly higher value parallel cap with RCA tubes.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 3, 2025 at 9:50 PM, Jim Shorney via groups.io <jimNU0C@...> wrote:
I would say your PA is not neutralized, although IIRC the parallel capacitor needed to be changed for a certain brand of tube. Someone else probably knows.
On Thu, 3 Apr 2025 21:25:37 -0400 (EDT)
"n4buq via groups.io" <n4buq@...> wrote:
> I then noticed the neutralization capacitor is fully open. I don't know if that's necessarily a bad thing but I can't help but think it should have at least a little capacitance.
--
73
-Jim
NU0C
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Re: PTO makes scraping sound
Isould have my TR-4Cw RIT open next week. ?If you still need the info then I can get it and post here.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Apr 4, 2025 at 12:13 AM, Mark N2DMI via groups.io < markkiziuk1@...> wrote:
Not on the PTO schematic but on the BIG schematic of the entire rig is where I want to know where the output of the PTO is connected to?
Mark
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Re: Tuning a pi-Network Output
IIRC, you need a slightly higher value parallel cap with RCA tubes.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 3, 2025 at 9:50 PM, Jim Shorney via groups.io < jimNU0C@...> wrote:
I would say your PA is not neutralized, although IIRC the parallel capacitor needed to be changed for a certain brand of tube. Someone else probably knows.
On Thu, 3 Apr 2025 21:25:37 -0400 (EDT)
"n4buq via groups.io" <n4buq@...> wrote:
> I then noticed the neutralization capacitor is fully open. I don't know if that's necessarily a bad thing but I can't help but think it should have at least a little capacitance.
--
73
-Jim
NU0C
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T-4XC "On" Decreases RX Performance?
Not really a big deal but thought I would check in to see if this is common.?
?
R-4C tied into T-4XC in normal transceive config. I'll listen around on the R-4C for a while, and I'll turn on the T-4 if I think I'll be transmitting in the next few minutes.?
?
Immediate drop in RX signal by a few S-units. Rx signal also shifts in frequency by maybe 100Hz. I can even duplicate this with the 25KHz calibrator.?
?
Turning off T-4XC "lights up" the receiver again.?
?
Common??
--
Craig/W8CS
Greenville, SC
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Re: Transceive with DDS VFO
OK, thanks.? I'm experimenting with one of the I0CG DDS-4 units. In the DDS-4 manual, one of the recommended uses is to run the DDS output to the INJ jack on the T4 transmitter, so that's what got me thinking about other boatanchor transmitters instead of the T4.
--Ed, N3CW--
?
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Re: Identifying "Soft" Final Tubes
I think something else needs to be considered when there is discussion about how long the 6/12JB6 tubes will last is our present times.? When a lot of the folks that are regular contributors to this group got started with ham radio we had tube type PAs that required dipping and loading.? We learned how to use reduced drive to get to the initial dip and then bring up the power and stay in resonance.?? Now days there are lots of people that have had most of their experience with solid state equipment that does not require PA loading and if they have a poor antenna match or worse they usually have protection from a foldback circuit.
Having? groups like this hopefully will make the newer operators of these older pieces of equipment aware sooner rather than later about the proper "care and feeding" of these fine pieces of vintage equipment.
73, Ron? wa7gfe
?
I stand corrected. The difference between a tech (me) and a trained engineer.?
Having said that, the sweep tubes will stand up to a lot of use, as long as they aren¡¯t abused.?
Having
also worked on a few Kenwood hybrids, I¡¯ve seen more toasted 6146¡¯s in
the last few years than 6JB6¡¯s and the KW rigs weren¡¯t used on 11m.?
If you do your initial plate-tuning at 150mA or so, you¡¯ll get lots of life out of the finals.?
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Re: PTO makes scraping sound
Not on the PTO schematic but on the BIG schematic of the entire rig is where I want to know where the output of the PTO is connected to?
Mark
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Re: Transceive with DDS VFO
In order to do what you suggest, you would need a device to offset the ¡°T¡± VFO signal to the transmitter operating frequency since the 2-C has no local oscillator or mixer to convert the VFO signal from the 5.0 to 5.5 MHz range to the transmitter operating frequency.?
Now one could possibly program a digital VFO such as yours to sense transmit status and automatically perform the offset in transmit. That would be a neat product for someone to produce!
Gary?
W0DVN
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On Apr 3, 2025, at 1:49?PM, Gary WB6OGD via groups.io <winbladgary@...> wrote:
? Well, I have..? sort of.? I think you are missing some important steps though.
?
Signals available in an R-4 are the PTO (5-5.5MHz on all bands) or the INJ (11.1MHz above operating frequency).
The 2NT needs an on operating frequency (or sub-harmonic?) signal.
?
And don't forget you need a frequency offset of your desired cw audio tone.
?
I built a "transceive adapter" with an Arduino and Si5351 board.
I measure the PTO frequency, do a calculation, then program the Si5351.
?
I used it to transceive my 75S-3B with my T-4XB.? Worked slick.? I also modified my B-Line with Arduinos and Si5351s in both
R-4B and T-4XB and transceive by one-wire digital bus.
?
Can't just use a "T " connection but it is possible with some hardware and software creativity.
73,
Gary
WB6OGD
?
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Re: Tuning a pi-Network Output
Well hey, it lasted 50 years! I have not heard of this failure before. It seems to me to be just an old age failure. Perhaps the collar had a weak spot or something. But by all means, do inspect it or replace it with a better designed cap if it concerns you. Some years back I was called over by a friend who was having netralization issues with his new-to-him TR4. It was a 30 second fix. I peeked in at the capacitor and the end plate had a bent corner that was making it short out. I straightened it out and we neutralized the rig. There was no damage to the rig or operator. It does pay to do a visual inspection first. On Thu, 3 Apr 2025 21:57:53 -0400 (EDT) "n4buq via groups.io" <n4buq@...> wrote: Thanks, Jim.
This is concerning:
73,
Barry - N4BUQ -- 73 -Jim NU0C
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Re: Tuning a pi-Network Output
Thanks, Jim.
This is concerning:
73,
Barry - N4BUQ
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I would say your PA is not neutralized, although IIRC the parallel capacitor
needed to be changed for a certain brand of tube. Someone else probably knows.
On Thu, 3 Apr 2025 21:25:37 -0400 (EDT)
"n4buq via groups.io" <n4buq@...> wrote:
I then noticed the neutralization capacitor is fully open. I don't know if
that's necessarily a bad thing but I can't help but think it should have at
least a little capacitance.
--
73
-Jim
NU0C
|
Re: Tuning a pi-Network Output
I would say your PA is not neutralized, although IIRC the parallel capacitor needed to be changed for a certain brand of tube. Someone else probably knows. On Thu, 3 Apr 2025 21:25:37 -0400 (EDT) "n4buq via groups.io" <n4buq@...> wrote: I then noticed the neutralization capacitor is fully open. I don't know if that's necessarily a bad thing but I can't help but think it should have at least a little capacitance. -- 73 -Jim NU0C
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Re: Tuning a pi-Network Output
Apples and oranges. The TR7 40M problem is a common mode feedback path through the high pass filter module. Tube neutralization deals with only the PA circuit (and occasionally the driver tube has its own neutralization adjustment). On Thu, 03 Apr 2025 23:41:54 +0000 "Steve Wedge, W1ES/4 via groups.io" <w1es@...> wrote: Then we have the 40m oscillations in the TR7, so I guess these items aren't cast in stone. -- 73 -Jim NU0C
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Re: For Sale: Drake TR-7 to R-7 interconnect cable
I've always appreciated that some will pay for convenience and for that, the price isn't out of line.
I'm a pretty good carpenter but I'm also nearly 70, with anaemia and a bum foot. I'm starting my search for someone to do some carpentry on one of my rentals. I just can't do some of the lifting and despite being retired, I'm too damned busy keeping up three houses, so I'm letting the rentals go to trades when they need work. I sort of feel like I'm slacking but I'm beginning to lose that feeling :-)
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with Proton Mail secure email.
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On Thursday, April 3rd, 2025 at 8:31 PM, Jim Shorney via groups.io <jimNU0C@...> wrote: Pretty sure mine cost me less than $20 to build and that includes two new Jones connectors. But I had the wire and cable I needed already. Cinch has Jones connectors still on their web site and they have also been manufactured by other parties. While I have to admire the capitalism in getting $100 for a simple passive cable IMO that is way too much. But I'm glad you found one. :) That reminds me, I do need to build another.
On Thu, 03 Apr 2025 06:32:12 -0700
"Tom KF5WBS via groups.io" Tombrantoncpa@... wrote:
After I purchased my R7 receiver I began the search for the connecting cable from the TR-7 to the R7 which would allow transceiver operations. I had no success and had just about given up when two came on the market. I acquired both and would like to pass along the unused one to another ham who is searching for the elusive cable. Full disclosure: this is not an original Drake cable but instead came from the aftermarket. That said, its new and works with my rig. The price is $100 shipped and PayPal is fine. I know $100 for a four foot cable is high but it seems the Cinch Jones connectors used are very hard to source nowadays making it difficult to homebrew the cable. Any questions please contact me off list. Thanks,
Tom KF5WBS
--
73
-Jim
NU0C
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Re: Another TR7 Journey begins
I am always suspicious when someone tells me a board is "bad". That seems to show a lack of enthusiasm to do the necessary component level troubleshooting. Fixing "bad" boards is just something a tech does unless dirt cheap replacements from China make it not cost effective. We don't have that problem here. :D More comments below. On Thu, 03 Apr 2025 10:44:15 -0700 "Bill NZ0T via groups.io" <nz0tham@...> wrote: 1.? ?PA finals are bad.
2.? ?Mother board is bad.
3.? ?LPF assembly is bad. 1. Full output on the low bands suggests that the Finals are fine. 2. I would only consider a Parent board "bad" if it is burned beyond repair. 3. Probably just switch contacts in need of cleaning. Solder connections may be suspect, or a (rare) capacitor failure. If you have it out you can easily sweep the filter sections with a NanoVNA. When I asked for details I was told: 1. The TR7 was putting out full power on the lower bands, on the upper bands the final went into oscillation.
2. The oscillator would not come on frequency because of a bad crystal.
3.? ?T he LP filter had a broken rotor switch.
4. The mother board is bad? because when you push down on the board some of the plugin boards stop working. 1. If there is indeed and oscillation leave this problem for last. A feedback loop after the ALC control point will to make the ALC ineffective. The most common oscillation in the TR7 is the infamous 40 Meter oscillation. There is a fix for that. One of my rigs was oscillating on other bands due to leaky driver transistors. 2. Comments below. 3. That should be an easy visual confirmation as you noted. 4. Parent board intermittents are likely "Molexia" on either male pins or female sockets, or failed solder joints on male pins. When I sent him the rig TX and RX were working but the ALC was not.? There was also an issue with not being able to get the 8.05 oscillator to 5.645 mHz after trying various capacitor values for C1029 on the PBT/Ref board and adjusting C1030. I remember going over this with you. It is a mystery but it can be solved. You should be able to get the 8.05 on frequency with the padder capacitance. We can look at that after the other problems are resolved. The ALC is pretty simple. It relies on the output of the wattmeter section. Forward watts for ALC level, reverse watts for SWR protection. What may throw you off is the op amp is a Norton amp and operates on current rather than voltage. It is a high impedance circuit so flux residue on the board could potentially affect it. Make sure the board is squeaky clean and the ground connections are tight, then follow the voltages. There are no unobtanium parts here. ALC is one of the last thing you adjust during alignment. Proper operation and SWR null in the Wattmeter circuit are essential. -- 73 -Jim NU0C
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Re: Tuning a pi-Network Output
I took the PA cage off because it had a concavity to it that bothered me since it made the top of the cage that much closer to the plate caps.? I then noticed the neutralization capacitor is fully open.? I don't know if that's necessarily a bad thing but I can't help but think it should have at least a little capacitance.? I'll find out when I get around to adjusting it.
73, Barry - N4BUQ
The neut procedure is but no mention is made of what happens on the lower bands.
Neutralisation is most important at the highest frequencies, I have been told for years.? Being a bit "off" on lower bands is supposedly less critical.
Then we have the 40m oscillations in the TR7, so I guess these items aren't cast in stone.??
For the purposes of the TR-4(any), I'm guessing that 40m neut isn't as important.? There isn't one setting that causes exact plate-dip-max-power-out coincidence on all bands.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Thursday, April 3rd, 2025 at 11:03 AM, Rob Sherwood via groups.io <rob@...> wrote:
Isn¡¯t this behavior discussed under neutralization in the manual? ?Rob, NC0B?
On Apr 3, 2025, at 8:19?AM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Barry, I¡¯ve found with the TR-3/4 that they don¡¯t 100% neutralise on all bands ¡ª especially 40m but sometimes 20m as well. It is unavoidable and the modeling of it is way above my pay grade.?
I still neutralise on the highest 10m band available (newer rigs made the upper two 10m bands
Optional). If all you have is the low 10m band Xtal, run the PTO to 28.6 and neutralise only after checking for coincident dip And max Power out.?
I keep my TR¡¯s at the plate dip, as it¡¯s passing less current. Chances are, you may lose 10-20W output but that difference is probably not detectable at the other end.?
Also, be mindful of ¡°rogue¡± resonances when tuning the driver. Stick within the range shown by the alignment procedure: I.e., if the preset alignment is at 7, avoid any peaks that are at, say, 2.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 3, 2025 at 09:53, n4buq < n4buq@...> wrote:
I don't think I've ever owned a power meter and now I have one in my MN-2000. Tuning up my TR-4, I notice that maximizing the output power doesn't necessarily coincide with the "dip" in plate current but, instead,
seems to occur on the "edge" of that dip. Is this normal?
From many, many years ago, with only a plate meter, I always adjusted with the dip at its minimum value but now I'm wondering if that wasn't yielding maximum power output. Furthermore, I presume that getting the dip first and then tweaking for maximum output
is the most efficient way to run. Is that correct? Is what I'm seeing normal? I presume so but after all these years, I'm beginning to wonder.
If it matters, I'm currently only tuning into a Drake dummy load.
Thanks,
Barry - N4BUQ
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Re: Another TR7 Journey begins
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Re: For Sale: Drake TR-7 to R-7 interconnect cable
Pretty sure mine cost me less than $20 to build and that includes two new Jones connectors. But I had the wire and cable I needed already. Cinch has Jones connectors still on their web site and they have also been manufactured by other parties. While I have to admire the capitalism in getting $100 for a simple passive cable IMO that is way too much. But I'm glad you found one. :) That reminds me, I do need to build another. On Thu, 03 Apr 2025 06:32:12 -0700 "Tom KF5WBS via groups.io" <Tombrantoncpa@...> wrote: After I purchased my R7 receiver I began the search for the connecting cable from the TR-7 to the R7 which would allow transceiver operations.? I had no success and had just about given up when two came on the market.? I acquired both and would like to pass along the unused one to another ham who is searching for the elusive cable.? Full disclosure: this is not an original Drake cable but instead came from the aftermarket.? That said, its new and works with my rig.? The price is $100 shipped and PayPal is fine.? I know $100 for a four foot cable is high but it seems the Cinch Jones connectors used are very hard to source nowadays making it difficult to homebrew the cable.? Any questions please contact me off list.? Thanks,
Tom KF5WBS -- 73 -Jim NU0C
|
Re: Tuning a pi-Network Output
The neut procedure is but no mention is made of what happens on the lower bands.
Neutralisation is most important at the highest frequencies, I have been told for years.? Being a bit "off" on lower bands is supposedly less critical.
Then we have the 40m oscillations in the TR7, so I guess these items aren't cast in stone.??
For the purposes of the TR-4(any), I'm guessing that 40m neut isn't as important.? There isn't one setting that causes exact plate-dip-max-power-out coincidence on all bands.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Thursday, April 3rd, 2025 at 11:03 AM, Rob Sherwood via groups.io <rob@...> wrote:
Isn¡¯t this behavior discussed under neutralization in the manual? ?Rob, NC0B?
On Apr 3, 2025, at 8:19?AM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
?
Barry, I¡¯ve found with the TR-3/4 that they don¡¯t 100% neutralise on all bands ¡ª especially 40m but sometimes 20m as well. It is unavoidable and the modeling of it is way above my pay grade.?
I still neutralise on the highest 10m band available (newer rigs made the upper two 10m bands
Optional). If all you have is the low 10m band Xtal, run the PTO to 28.6 and neutralise only after checking for coincident dip And max Power out.?
I keep my TR¡¯s at the plate dip, as it¡¯s passing less current. Chances are, you may lose 10-20W output but that difference is probably not detectable at the other end.?
Also, be mindful of ¡°rogue¡± resonances when tuning the driver. Stick within the range shown by the alignment procedure: I.e., if the preset alignment is at 7, avoid any peaks that are at, say, 2.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 3, 2025 at 09:53, n4buq < n4buq@...> wrote:
I don't think I've ever owned a power meter and now I have one in my MN-2000. Tuning up my TR-4, I notice that maximizing the output power doesn't necessarily coincide with the "dip" in plate current but, instead,
seems to occur on the "edge" of that dip. Is this normal?
From many, many years ago, with only a plate meter, I always adjusted with the dip at its minimum value but now I'm wondering if that wasn't yielding maximum power output. Furthermore, I presume that getting the dip first and then tweaking for maximum output
is the most efficient way to run. Is that correct? Is what I'm seeing normal? I presume so but after all these years, I'm beginning to wonder.
If it matters, I'm currently only tuning into a Drake dummy load.
Thanks,
Barry - N4BUQ
|
Re: PTO makes scraping sound
The green wire goes to the place where the PTO output goes.
In your transceiver, there should be a spade connector on that board. that has no other wire connected to it.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Thursday, April 3rd, 2025 at 11:58 AM, Mark N2DMI via groups.io <markkiziuk1@...> wrote:
Hi Peter, yes I took photos of EVERYTHING that got connected to the PTO. On the PTO output (which is the green wire) it goes to a small board. Where on the schematic is that going to??
Mark
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Re: PTO makes scraping sound
Hi Peter, Yes I have all of K4OAH service manuals for this rig plus whatever was included in the package. I believe I ordered everything about a month ago when I got the other TR-4CW without the RIT. I got everything but I haven¡¯t really sat down and went through things. I just work a lot of hours at corporate that when I finally come home from work I just want to shower, eat and crash! Not too much time to do my own things. Such is my life!
I believe I have off this Saturday (and every Saturday for this month) then it¡¯s back to the crazy hours once again! When I have some energy I will try to look what K4OAH put together.
Mark
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Craig W8CS
Ron Magnus
Mark N2DMI
Jim Shorney