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
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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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Re: Call me a barbarian¡
When I got my first C Line (an early one with 4 position filter switch), I was disappointed at the feel of the nylon-geared PTO¡¯s. At the time (1984) I figured it was the price to be paid for a PTO with better accuracy.?
The old PTO¡¯s have a wonderful feel when properly adjusted.?
The fluted knob is perfect for turning with the index finger. It ¡°looks old¡± but tactically, it is superior to the BLine knob.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 3, 2025 at 18:01, Gary WB6OGD via groups.io < winbladgary@...> wrote:
I agree.
AND, the metal mechanism feels soo much better than the plastic two disc C line!
73,
Gary
WB6OGD
On Thu, Apr 3, 2025 at 2:48?PM Steve Wedge, W1ES/4 via
<w1es=
[email protected]> wrote:
Playing with my A Line today, after fixing a damaged T-4 and then cleaning out the relay of my minty T-4X.?
I¡¯m not a fan of the flat disc ¡°skirt¡± for the main tuning but by golly, I love the feel of that fluted knob!? Granted, these rigs look like it¡¯s still 1967 but I don¡¯t feel the need for a thumb or finger indent!
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
|
Re: Call me a barbarian¡
I agree. AND, the metal mechanism feels soo much better than the plastic two disc C line! 73, Gary WB6OGD
On Thu, Apr 3, 2025 at 2:48?PM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Playing with my A Line today, after fixing a damaged T-4 and then cleaning out the relay of my minty T-4X.?
I¡¯m not a fan of the flat disc ¡°skirt¡± for the main tuning but by golly, I love the feel of that fluted knob!? Granted, these rigs look like it¡¯s still 1967 but I don¡¯t feel the need for a thumb or finger indent!
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
|
Re: Call me a barbarian¡
That's the best part!? I was good friends with a guy whose dad was a ham and he had a B-Line.? We both had our novice licenses and his dad sort-of frowned on it if we messed with his new rigs (don't blame him very much) but I still remember seeing them and wanting something like that so much.? Good times.
Barry - N4BUQ
Granted, these rigs look like it¡¯s still 1967 but I don¡¯t feel the need for a thumb or finger indent!
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
|
Playing with my A Line today, after fixing a damaged T-4 and then cleaning out the relay of my minty T-4X.?
I¡¯m not a fan of the flat disc ¡°skirt¡± for the main tuning but by golly, I love the feel of that fluted knob! ?Granted, these rigs look like it¡¯s still 1967 but I don¡¯t feel the need for a thumb or finger indent!
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
|
You guys are fantastic! I appreciate all the help. I realigned the CO, which was pretty far off, and then balanced it. ?I also switched mics to a D104. My TX audio sounds great on both sidebands now. ?
I can¡¯t thank you guys enough!
?
?
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Re: Tuning a pi-Network Output
I meant to add do NOT disconnect the plates of pentodes/tetrodes alone, the screens will try to absorb all the output of the cathode and burn up. If the screens are disconnected the electron flow in the tube will be cut off, which is what you want. Not necessary to disconnect both screens and plates, screens are enough.
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On 4/3/2025 2:07 PM, Richard Knoppow via groups.io wrote:
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: Tuning a pi-Network Output
That is correct. You probably want something more sensitive than a VTVM, a scope is ideal but a radio receiver works well. As long as the screens are disconnected little or no power will come out. For tetrodes/pentodes it is not necessary to disconnect the plates. The neutralizing capacitor forms a bridge with the internal capacitances of the tube. When correctly adjusted the bridge nulls out the coupling through the tube. There are better explanations on the web.
You can start at some relatively low frequency, probably 20 meters is suitable, get a null, and then go up to 10 meters (or whatever the maximum frequency is) and refine the adjustment if necessary. The reason for retesting using the Drake method once the screens are reattached is that the Drake method is the most sensitive way to adjust the neutralization. If the screen method is used first you will be right on or very close so there will not be difficulty with the Drake method.
The driver can be adjusted at very low power before doing the neutralization. One problem with the internal feedback is that its possible to get the final amp oscillating is close to full power simply by adjustment of the plate. The warning is that there is power out with no drive and the output does not vary with the drive level. The output stage is NOT amplifying, it is oscillating and can burn up very quickly.
Note that some rigs, notably Kenwood, have switches for the screen voltage especially for neutralizing them. I am only familiar with a couple of Drake rigs but in both the screen feeds are easy to get to and disconnect.
I should not have to add this but better: For triodes it is the plates that should be disconnected. For tetrodes or pentodes disconnect the screens, that will cut the tube off. Do NOT disconnect the plates alone. You can disconnect BOTH screens and plates but disconnecting the plates is not necessary.
Success with this (I think you make your own luck) and please report back on your results.
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On 4/3/2025 12:41 PM, n4buq wrote: Richard,
If I understand correctly, for the three 6JB6 (tetrodes), I can disconnect the screen connection (one connection goes to all three tubes) and then I can either scope the output or use an HF VTVM at the antenna jack to see the spurious oscillation and null it. Is that correct?
Thanks!
Barry - N4BUQ
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: Transceive with DDS VFO
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: Another TR7 Journey begins
Before messing seriously with the motherboard, I would pull all the cards
and clean the Molex pins with DeOxit.
- Jerry, KF6VB
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On 2025-04-03 10:44, Bill NZ0T via groups.io wrote: I'm back again with the TR7. I put it away because I was frustrated
and have spent some time since bring a Heathkit SB-102 back to life.
That went well and now I'm ready to tackle the TR& again.
I spent the morning taking every plugin board out including the
display board and the boards underneath it. Then the tedious task of
taking the LPF module out as that's where I think most of the issues
are. I took LOTS of photos of all the wire connections so hopefully
once it's time to put it back I'll get those soldered correctly. To
refresh the issues here is what WB4HFN told me after he looked at the
rig and told me it is not repairable:
1. PA finals are bad.
2. Mother board is bad.
3. LPF assembly is bad.
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.
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.
So my plan is to thoroughly check out the LPF module (neither of the
rotors is broken) for anything bad then check that the wiring from the
module is correct and OK. Then thoroughly check out the mother board
for any issues. Any other ideas as to what to check out are greatly
appreciated!
73, Bill NZ0T
Links:
------
[1] /g/DRAKE-RADIO/message/84103
[2] /mt/104249254/243852
[3] /g/DRAKE-RADIO/post
[4] /g/DRAKE-RADIO/editsub/243852
[5] /g/DRAKE-RADIO/leave/12260778/243852/767576506/xyzzy
|
Re: Tuning a pi-Network Output
Richard,
If I understand correctly, for the three 6JB6 (tetrodes), I can disconnect the screen connection (one connection goes to all three tubes) and then I can either scope the output or use an HF VTVM at the antenna jack to see the spurious oscillation and null it. Is that correct?
Thanks!
Barry - N4BUQ
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It is NOT normal. It is a sign that the amplifier needs to be
neutralized. Plate dip and power peak should be simultaneous. The
coincidence of these two is a very sensitive measure of neutralization.
For the T-4 and some other models Drake specifies setting the
neutralization using the coincidence but if the neutralization is not
almost correct this may be a difficult adjustment to make. A better way
to check neutralization is to measure the feed through of drive power to
the plate by disconnecting the screens of tetrodes or the plates of
triodes. Use something sensitive like a receiver or scope to see what is
coming through, then set the neutralization adjustment to null it. Once
that is adjusted you can check the neutralization via the Drake method,
that is see if the plate dip and power peak are simultaneous.
There is a great deal of information on neutralizing on the web.
You should be familiar with the theory of what is being done. The idea
is roughly to eliminate any positive feedback through the tubes by means
of a sort of bridge circuit. It is done to prevent the tubes from
oscillating. If that happens the oscillation will be uncontrolled and
destroy the tubes. In general neutralization is more critical at higher
frequencies. You can get approximate neutralization at, say 20 meters,
and then check it at 10 meters making any small adjustments necessary.
BTW, this is not a matter of the type of circuit used to match the
output to the antenna, neutralization is necessary for any type of
output pi-network or otherwise.
On 4/3/2025 6:53 AM, 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
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: Tuning a pi-Network Output
It is NOT normal. It is a sign that the amplifier needs to be neutralized. Plate dip and power peak should be simultaneous. The coincidence of these two is a very sensitive measure of neutralization. For the T-4 and some other models Drake specifies setting the neutralization using the coincidence but if the neutralization is not almost correct this may be a difficult adjustment to make. A better way to check neutralization is to measure the feed through of drive power to the plate by disconnecting the screens of tetrodes or the plates of triodes. Use something sensitive like a receiver or scope to see what is coming through, then set the neutralization adjustment to null it. Once that is adjusted you can check the neutralization via the Drake method, that is see if the plate dip and power peak are simultaneous.
There is a great deal of information on neutralizing on the web. You should be familiar with the theory of what is being done. The idea is roughly to eliminate any positive feedback through the tubes by means of a sort of bridge circuit. It is done to prevent the tubes from oscillating. If that happens the oscillation will be uncontrolled and destroy the tubes. In general neutralization is more critical at higher frequencies. You can get approximate neutralization at, say 20 meters, and then check it at 10 meters making any small adjustments necessary.
BTW, this is not a matter of the type of circuit used to match the output to the antenna, neutralization is necessary for any type of output pi-network or otherwise.
toggle quoted message
Show quoted text
On 4/3/2025 6:53 AM, 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
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: PTO makes scraping sound
I use the camera on my phone for taking photos of lots of things before diving into projects..In fact that is what it is mostly used for.. It's one of the best tools to come?along
Mark:
I think the best approach would be to wait until me, or perhaps someone else, can open their TR-4CW/rit and check those two connections, take a pic, etc.? I am not able to do that until early next week....Tuesday likely.? My TR-4CW/rit is on an upper shelf on that desk and is easy to pull out.
To avoid issues like this I ALWAYS take a picture of the PTO wire connections before I remove a PTO.? Typically I don't keep the pictures of every one I've done, but the TR-4CW/rit would be a good one to keep on file so I'll take pics of my own when I can and post them to the group files.
73, Peter VE7PS
Sorry Peter you did tell me where the RIT wire goes. I forgot. Sorry!
On the PTO output signal, where does that go on the rig!
Mark
|
Has anyone tried using a DDS VFO connected to a receiver such as the R-4B, and also connected via a "T" to the VFO input of a boatanchor transmitter such as the 2-NT? I'm thinking that might work to give me transceive capability while I'm tuning with the DDS VFO, but I just haven't tried it yet.?
--Ed, N3CW--
?
|
Re: Another TR7 Journey begins
I'm back again with the TR7.? I put it away because I was frustrated and have spent some time since bring a Heathkit SB-102 back to life.? That went well and now I'm ready to tackle the TR& again.
?
I spent the morning taking every plugin board out including the display board and the boards underneath it.? Then the tedious task of taking the LPF module out as that's where I think most of the issues are.? I took LOTS of photos of all the wire connections so hopefully once it's time to put it back I'll get those soldered correctly.? To refresh the issues here is what WB4HFN told me after he looked at the rig and told me it is not repairable:
?
1.? ?PA finals are bad.
2.? ?Mother board is bad.
3.? ?LPF assembly is bad.
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.
?
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.
?
So my plan is to thoroughly check out the LPF module (neither of the rotors is broken) for anything bad then check that the wiring from the module is correct and OK.? Then thoroughly check out the mother board for any issues.? Any other ideas as to what to check out are greatly appreciated!?
?
73, Bill NZ0T
?
?
|
Jim Shorney
Mark N2DMI
Gary WB6OGD
Adam N0ZIB