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.

Sent from for iOS

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.

Sent from for iOS

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

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

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

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

On Apr 3, 2025, at 11:04?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 — 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.

Sent from for iOS

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