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Re: Tuned input

 

Jim, I understand your method. What I have trouble with is your antenna is acting as a filter? Is there an equation using the SWR of the 2nd and 3rd harmonic as limiting the output power of the harmonics? In other words if you operated at 3.5 mhz with a 1:1 SWR and your antenna was flat at 7 mhz what would that do to the second harmonic?? Not arguing, just curious. Hope this makes sense.

On Thursday, January 25, 2024 at 06:06:44 PM EST, Jim VE7RF <jim.thom@...> wrote:


On Thu, Jan 25, 2024 at 11:44 PM, W7WRX wrote:
Correct. Thats what I posted.? I tested it slightly less then that but in the ball park.? HOW are you testing to look at the second harmonic?? How is this done?? Nobody seems to know.
C
## Nanovna on kitchen table..( 4" screen) . Plug in the small telescopic ant into the nanovna...or short cable to a small short wire ant on kitchen floor.? ?You can pick up the cxr from the ant in backyard easy enough.? Set the freq range wide enough to cover the fundamental + 2nd harmonic.... or fundamental +? ?2nd and 3rd harmonics.?

Re: Tuned input

 

开云体育

With a spectrum analyser via an attenuator.

?

73

Peter, DJ7WW

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?

-----Original-Nachricht-----

Betreff: Re: [ham-amplifiers] Tuned input

Datum: 2024-01-25T23:44:32+0100

Von: "W7WRX" <clark@...>

An: "[email protected]" <[email protected]>

?

?

?

Correct. Thats what I posted.? I tested it slightly less then that but in the ball park.? HOW are you testing to look at the second harmonic?? How is this done?? Nobody seems to know.
C
?

From: [email protected] <[email protected]> on behalf of Peter Voelpel via groups.io <dj7ww@...>
Sent: Thursday, January 25, 2024 2:26 PM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Tuned input
?

Henry specified better then -50dB on harmonics and better then -35dB on IMD3 for 3K Ultra and 8K Ultra

?

?
Re: Tuned input

 

On Thu, Jan 25, 2024 at 11:44 PM, W7WRX wrote:
Correct. Thats what I posted.? I tested it slightly less then that but in the ball park.? HOW are you testing to look at the second harmonic?? How is this done?? Nobody seems to know.
C
## Nanovna on kitchen table..( 4" screen) . Plug in the small telescopic ant into the nanovna...or short cable to a small short wire ant on kitchen floor.? ?You can pick up the cxr from the ant in backyard easy enough.? Set the freq range wide enough to cover the fundamental + 2nd harmonic.... or fundamental +? ?2nd and 3rd harmonics.?
Re: Tuned input

 

开云体育

Correct. Thats what I posted.? I tested it slightly less then that but in the ball park.? HOW are you testing to look at the second harmonic?? How is this done?? Nobody seems to know.
C

From: [email protected] <[email protected]> on behalf of Peter Voelpel via groups.io <dj7ww@...>
Sent: Thursday, January 25, 2024 2:26 PM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Tuned input
?

Henry specified better then -50dB on harmonics and better then -35dB on IMD3 for 3K Ultra and 8K Ultra

?

?

73

Peter, DJ7WW

?

?

?

-----Original-Nachricht-----

Betreff: Re: [ham-amplifiers] Tuned input

Datum: 2024-01-25T22:06:17+0100

Von: "Jim VE7RF" <jim.thom@...>

An: "[email protected]" <[email protected]>

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?

Eimac states -52dbc for IMD3? on the 3CX-3000A7.? It's one of the cleanest tubes in their catalog.? ?Eimac uses a standard 2 tone test....done at 2 mhz.? ? I can't verify their specs.?

?

But I can see the 8k being severely degraded with that mickey mouse un-un setup.??

?

Re: Tuned input

 

开云体育

Henry specified better then -50dB on harmonics and better then -35dB on IMD3 for 3K Ultra and 8K Ultra

?

?

73

Peter, DJ7WW

?

?

?

-----Original-Nachricht-----

Betreff: Re: [ham-amplifiers] Tuned input

Datum: 2024-01-25T22:06:17+0100

Von: "Jim VE7RF" <jim.thom@...>

An: "[email protected]" <[email protected]>

?

?

?

Eimac states -52dbc for IMD3? on the 3CX-3000A7.? It's one of the cleanest tubes in their catalog.? ?Eimac uses a standard 2 tone test....done at 2 mhz.? ? I can't verify their specs.?

?

But I can see the 8k being severely degraded with that mickey mouse un-un setup.??

?
Re: Tuned input

 

Eimac states -52dbc for IMD3? on the 3CX-3000A7.? It's one of the cleanest tubes in their catalog.? ?Eimac uses a standard 2 tone test....done at 2 mhz.? ? I can't verify their specs.?

?

But I can see the 8k being severely degraded with that mickey mouse un-un setup.??
Re: Tuned input

 

I'm talking strictly about HARMONIC? reduction......NOT IMD.?


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?
Re: Tuned input

 

开云体育

Jim.? HOW are you testing IMD?? ?You must be using some other meathod other than the standard ARRL IMD Two tone?????? ?There is no way you can make those figures with a two tone IMD test. I think you must be testing another way?? Carrier???

Please tell me your procedure and test setup so we can figure out why your figures are so far off from any other source.? Even the tube manuals and amp manuals show IMD very different.? We must be talking about two different tests.

C

From: [email protected] <[email protected]> on behalf of Jim VE7RF via groups.io <jim.thom@...>
Sent: Thursday, January 25, 2024 9:23 AM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Tuned input
?
On Wed, Jan 24, 2024 at 02:26 AM, W7WRX wrote:
I think Jim must be talking about something else.? No way in hell an ameritron AL 1200 or 1500 does 50 db down. The manual shows -34 BEST case on best band.??
?
I got my 2 tone setup now and ran the radio to verify.? I will two tone the 8k and see what it shows. I wanted this data before adding the input.? I was using a carrier prior and just looking at the spec an lightly coupled. No attenuator.??
?
In any case the tuned input board reduces the harmonics by at least 20DB and can be as much as 30.?
?
Now Jim, what the heck are you talking about brother?? How are you testing to get -50 out of an ameritron?? ?You certainly can't be talking about IMD????? Confused...
?
C

###? BEFORE I got booted from W8JI's FB amplifier group,? I had brought up the topic of harmonics.? I said that if I could get -30 db for 2nd harmonic, I'm happy.? None of my ants are resonant on their 2nd or all other even harmonics.? My 40m yagi does not resonate on it's 3rd harmonic.....due to the loading scheme used. (it resonates on 24 mhz....and will screw up a 12m yagi).?
JI stated his AL-1200 is -50 db on 40m.? ?On the 3 x big ameritron amps, they all use the identical PI / PI-L networks.? ?They use a PI-L on 160+80m.? On 40-10m it's just a simple PI.?

?

##? FCC spec is? -44 db for 2nd and all other harmonics...(for 1.5 kw. At 10 kw, it's then -50db)? ?Typ PI? / PI-L? networks have the 3rd harmonic 10 db lower than the 2nd harmonic....and the 4th harmonic is 10 db lower than the 3rd.?

##? All those german amps use a simple PI network, and he rates em at -50 db for 2nd harmonic.?

?

##? Nowhere in any eng books I have, not on Rauch's tuned input writeup does it mention that the PI tuned input on a GG amp will improve the harmonic suppression on the kw OUTPUT end.? That's the job of the KW PI / PI-L output network.??

## The amplifier does not amplify harmonics, it generates them.??

##? But you are saying the PI tuned input does improve harmonic suppression from measurements. If that's the case, you are onto something significant.? ?And the higher the Q for the tuned input, the harmonics would / should be even more
suppressed...(and IMD should improve even more).?

?

## Even though the PI network is a LP filter...it will still have an upper? + lower freq limit, where the input SWR rises.? I can see this easily on both the tuned input....and also the KW output.? IF Q is kept constant, every time I move up in band, the 2:1 SWR BW doubles.? (160-80-40-20-10m).? (15 m is between 20+10m).? That's also how I find out if I suffer from the dreaded...'suck out'? problem.? That typ occurs when a NON shorting bandswitch is used....and the tank coil covers 160m.? It also happens if? a roller coil is used for 160-10m.? What happens with suck out is..... everything is fine on 160-30m. On 20-10m, the 2:1 SWR BW is extremely? narrow, and tuning is screwball.?

?

##? On these manually tuned, tuned inputs, we can get away with a higher Q, since both caps are adjustable from the front panel...non issue.?

IE: here is what I use for the 3x3 / 3x6? ?50 ohm cathode Z.? ?I use a total network Q of? 4? ( and a input Q of 2..and an output Q of 2).? Input + output Q = total network Q.? ?When matching 50 ohms to 50 ohms, ( or 75 ohms to 75 ohms), input and output Q are the same..and both cap values are the same.? On the kw output side, when matching the say 2000 ohm plate load Z to the 50 ohm ant,? Total network Q is 12, and the input Q is 10..and output Q is 2.

?

160-1840 khz
C1 = 3460 pf
L = 3.46 uh
C2 = 3460 pf

?

80m - 3750 khz
C1 = 1698 pf
L = 1.7 uh
C2 = 1698 pf

?

40m? - 7150 khz
C1 =? 890 pf
L =? ?.89 uh?
C2 = 890 pf

?

30m - 10.125 mhz?
C1 =? 629 pf
L =? .63 uh
C2 = 629 pf

?

20M - 14.175 mhz
C1 = 449 pf
L =? .45 uh?
C2 = 449 pf

17m -? 18.118 mhz
C1 = 352 pf
L - .35 uh
C2 = 352 pf?

?

15m - 21.225 mhz
C1 = 300 pf
L = .3 uh
C2 = 300 pf

?

12m -? 24.94 mhz?
C1 = 255 pf
L = .26 uh
C2 = 255 pf

?

10m - 28.500 mhz
C1 = 223 pf
L =? .22 uh
C2 = 223 pf?

All tube C (grid to cathode) must be subtracted from the C2 values.?

?

As u can see from the above calcs we used, we are using a helluva lot more C1 + C2..and less coil? for each band. You would never use this (except warc bands) on any amp with bandswitched / relay switched fixed tuned inputs.? The 2:1 SWR BW would not be wide enough to cover the entire band in most cases.? On a manually tuned, tuned input, non issue.? ?IE: the kw output side will be tweaked? when qsy'ing..and the mating tuned input can also be tweaked at the same time.?

?

Jim? ?VE7RF?

?

?

?

?
Re: Tuned input

 

On Wed, Jan 24, 2024 at 02:26 AM, W7WRX wrote:
I think Jim must be talking about something else.? No way in hell an ameritron AL 1200 or 1500 does 50 db down. The manual shows -34 BEST case on best band.??
?
I got my 2 tone setup now and ran the radio to verify.? I will two tone the 8k and see what it shows. I wanted this data before adding the input.? I was using a carrier prior and just looking at the spec an lightly coupled. No attenuator.??
?
In any case the tuned input board reduces the harmonics by at least 20DB and can be as much as 30.?
?
Now Jim, what the heck are you talking about brother?? How are you testing to get -50 out of an ameritron?? ?You certainly can't be talking about IMD????? Confused...
?
C

###? BEFORE I got booted from W8JI's FB amplifier group,? I had brought up the topic of harmonics.? I said that if I could get -30 db for 2nd harmonic, I'm happy.? None of my ants are resonant on their 2nd or all other even harmonics.? My 40m yagi does not resonate on it's 3rd harmonic.....due to the loading scheme used. (it resonates on 24 mhz....and will screw up a 12m yagi).?
JI stated his AL-1200 is -50 db on 40m.? ?On the 3 x big ameritron amps, they all use the identical PI / PI-L networks.? ?They use a PI-L on 160+80m.? On 40-10m it's just a simple PI.?

?

##? FCC spec is? -44 db for 2nd and all other harmonics...(for 1.5 kw. At 10 kw, it's then -50db)? ?Typ PI? / PI-L? networks have the 3rd harmonic 10 db lower than the 2nd harmonic....and the 4th harmonic is 10 db lower than the 3rd.?

##? All those german amps use a simple PI network, and he rates em at -50 db for 2nd harmonic.?

?

##? Nowhere in any eng books I have, not on Rauch's tuned input writeup does it mention that the PI tuned input on a GG amp will improve the harmonic suppression on the kw OUTPUT end.? That's the job of the KW PI / PI-L output network.??

## The amplifier does not amplify harmonics, it generates them.??

##? But you are saying the PI tuned input does improve harmonic suppression from measurements. If that's the case, you are onto something significant.? ?And the higher the Q for the tuned input, the harmonics would / should be even more
suppressed...(and IMD should improve even more).?

?

## Even though the PI network is a LP filter...it will still have an upper? + lower freq limit, where the input SWR rises.? I can see this easily on both the tuned input....and also the KW output.? IF Q is kept constant, every time I move up in band, the 2:1 SWR BW doubles.? (160-80-40-20-10m).? (15 m is between 20+10m).? That's also how I find out if I suffer from the dreaded...'suck out'? problem.? That typ occurs when a NON shorting bandswitch is used....and the tank coil covers 160m.? It also happens if? a roller coil is used for 160-10m.? What happens with suck out is..... everything is fine on 160-30m. On 20-10m, the 2:1 SWR BW is extremely? narrow, and tuning is screwball.?

?

##? On these manually tuned, tuned inputs, we can get away with a higher Q, since both caps are adjustable from the front panel...non issue.?

IE: here is what I use for the 3x3 / 3x6? ?50 ohm cathode Z.? ?I use a total network Q of? 4? ( and a input Q of 2..and an output Q of 2).? Input + output Q = total network Q.? ?When matching 50 ohms to 50 ohms, ( or 75 ohms to 75 ohms), input and output Q are the same..and both cap values are the same.? On the kw output side, when matching the say 2000 ohm plate load Z to the 50 ohm ant,? Total network Q is 12, and the input Q is 10..and output Q is 2.

?

160-1840 khz
C1 = 3460 pf
L = 3.46 uh
C2 = 3460 pf

?

80m - 3750 khz
C1 = 1698 pf
L = 1.7 uh
C2 = 1698 pf

?

40m? - 7150 khz
C1 =? 890 pf
L =? ?.89 uh?
C2 = 890 pf

?

30m - 10.125 mhz?
C1 =? 629 pf
L =? .63 uh
C2 = 629 pf

?

20M - 14.175 mhz
C1 = 449 pf
L =? .45 uh?
C2 = 449 pf

17m -? 18.118 mhz
C1 = 352 pf
L - .35 uh
C2 = 352 pf?

?

15m - 21.225 mhz
C1 = 300 pf
L = .3 uh
C2 = 300 pf

?

12m -? 24.94 mhz?
C1 = 255 pf
L = .26 uh
C2 = 255 pf

?

10m - 28.500 mhz
C1 = 223 pf
L =? .22 uh
C2 = 223 pf?

All tube C (grid to cathode) must be subtracted from the C2 values.?

?

As u can see from the above calcs we used, we are using a helluva lot more C1 + C2..and less coil? for each band. You would never use this (except warc bands) on any amp with bandswitched / relay switched fixed tuned inputs.? The 2:1 SWR BW would not be wide enough to cover the entire band in most cases.? On a manually tuned, tuned input, non issue.? ?IE: the kw output side will be tweaked? when qsy'ing..and the mating tuned input can also be tweaked at the same time.?

?

Jim? ?VE7RF?

?

?

?

?
Re: LK 5xx Variable Cap Plates with pix attached

 

THE MFJ VARIABLE USED ON THE AL80B IS A SUITABLE REPLACEMENT WITH SIMILAR SPECIFICATIONS FOR THE SB-220, LK500 and others.?




On Wednesday, January 24, 2024, 2:44 PM, Tom Hellem <tom.hellem@...> wrote:

Vac variable sounding better all the time.
How about something like this?



The link shows 3 kv but the catalog lists it at 5 kv

K0SN

On Wed, Jan 24, 2024 at 12:31?PM Rich k0zx <k0zx.co@...> wrote:
Here is what Ameritron has replaced that part number with today (attached):
Re: LK 5xx Variable Cap Plates with pix attached

 

开云体育

The catalog is wrong. I used to have a few of those: very cute lil things and the voltage rating printed on the cap was just 3 kV (but that was in the days before I built hi-potters and actually tested the caps). There is no stop to prevent the screw from coming out of the cap and the "nose cone" from falling off. I bought em for use with 250Rs and 300As running on 2500V. Those are certainly not worth $300, IMOH, maybe $150.

If you didn't burn more than one or two of the plates too much, you can always clean up your existing one and reuse it. It'll be a few less pF capacitance; but except on the bottom of 160/80, you'll never notice that on the other bands. If you aren't, right now, right at minimum on 10 or 15 and just can't tolerate any extra capacitance at all, just install a 5 or 10 or 15 pF doorknob in parallel to get the total capacitance back up for the bottom of the lower bands. You probably need it, anyway, down there.

Steve, K0XP


On 1/24/2024 11:44 AM, Tom Hellem wrote:
Vac variable sounding better all the time.
How about something like this?



The link shows 3 kv but the catalog lists it at 5 kv

K0SN

On Wed, Jan 24, 2024 at 12:31?PM Rich k0zx <k0zx.co@...> wrote:
Here is what Ameritron has replaced that part number with today (attached):
--
NO on ARRL Bylaw 46!!! See my QRZ.com page at

Re: LK 5xx Variable Cap Plates with pix attached

 

开云体育

And that is an old used capacitor of unknown quality and status of vacuum.

?

73

Peter

?

?

?

-----Original-Nachricht-----

Betreff: Re: [ham-amplifiers] LK 5xx Variable Cap Plates with pix attached

Datum: 2024-01-24T21:38:57+0100

Von: "mike repinski via groups.io" <mikflathead@...>

An: "[email protected]" <[email protected]>

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Nothing personal to the party fixing this but you know the saying "hams are cheap"
?
On Wednesday, January 24, 2024 at 02:44:37 PM EST, Tom Hellem <tom.hellem@...> wrote:
?
?
Vac variable sounding better all the time.
How about something like this?
?
?
The link shows 3 kv but the catalog lists it at 5 kv
?
K0SN

On Wed, Jan 24, 2024 at 12:31?PM Rich k0zx <k0zx.co@...> wrote:
Here is what Ameritron has replaced that part number with today (attached):

?

?

?
Re: LK 5xx Variable Cap Plates with pix attached

 

Nothing personal to the party fixing this but you know the saying "hams are cheap"

On Wednesday, January 24, 2024 at 02:44:37 PM EST, Tom Hellem <tom.hellem@...> wrote:


Vac variable sounding better all the time.
How about something like this?



The link shows 3 kv but the catalog lists it at 5 kv

K0SN

On Wed, Jan 24, 2024 at 12:31?PM Rich k0zx <k0zx.co@...> wrote:
Here is what Ameritron has replaced that part number with today (attached):
Re: LK 5xx Variable Cap Plates with pix attached

 

Vac variable sounding better all the time.
How about something like this?



The link shows 3 kv but the catalog lists it at 5 kv

K0SN

On Wed, Jan 24, 2024 at 12:31?PM Rich k0zx <k0zx.co@...> wrote:
Here is what Ameritron has replaced that part number with today (attached):
Re: LK 5xx Variable Cap Plates with pix attached

 

开云体育

No difference on plate spacing for that cap vrs the old part number . Spacing and plate count identical to a sb220

Same Max capacitance value as yours?

Making this harder then you need to?



Amp guy llc
Amprepairguy.com
YouTube Amp repair guy
203-892-4119

On Jan 24, 2024, at 2:31 PM, Rich k0zx <k0zx.co@...> wrote:

?Here is what Ameritron has replaced that part number with today (attached):
<varcap.JPG>
Re: LK 5xx Variable Cap Plates with pix attached

 

Here is what Ameritron has replaced that part number with today (attached):

varcap.JPG

Re: LK 5xx Variable Cap Plates with pix attached

 

开云体育

You are in correct?

Here is the spec for the cap used on the plate side for the al80b and al572?

It HAS a voltage rating of 3.5 kv

Again here is the Ameritron part number?

image1.png

image0.jpeg

Amp guy llc
Amprepairguy.com
YouTube Amp repair guy
203-892-4119

On Jan 24, 2024, at 2:05 PM, Rich k0zx <k0zx.co@...> wrote:

?Spoke with rob, found in catalog, but unfortunately this cap is significantly lower voltage rating than the 3.5kv needed in these amp supply boxes. Also plate count different, so it most likely closer plates and so lower voltage rating. Perfect for the AL-xxxs but looks like not prime time for this radio. Rebuilding if I can get the plates is ok here, no mods needed if find. But tnx for the leads
rich

Re: LK 5xx Variable Cap Plates with pix attached

 

Spoke with rob, found in catalog, but unfortunately this cap is significantly lower voltage rating than the 3.5kv needed in these amp supply boxes. Also plate count different, so it most likely closer plates and so lower voltage rating. Perfect for the AL-xxxs but looks like not prime time for this radio. Rebuilding if I can get the plates is ok here, no mods needed if find. But tnx for the leads
rich
Re: LK 5xx Variable Cap Plates with pix attached

 

ok, Jim, tnx for that...he just gave me some contact info too so hopefully that's the ticket
rich
Re: Tuned input

 

开云体育

Cool thanks , that will come in handy some day



Amp guy llc
Amprepairguy.com
YouTube Amp repair guy
203-892-4119

On Jan 23, 2024, at 11:13 PM, W7WRX <clark@...> wrote:

?
Not paul.

Attached is the page in service manual.? They want you to Preset both coils.

They revised the values of the tune and load door knobs per band.? It's very different from early and mid models.?

They also changed the solenoids/relays for those door knobs.? Mine has the later thicker plate devices. They look mint.

The amp will be used for DXing at pretty low power.? The big advantage for me is the 16 presets.? I can simply turn a knob, make a contact and jump bands.? Don't care if it makes slot of power.? Would blow up my mosley anyways.?

The fact that this thing has a horrible input match just annoyed me so I will fix that and it should be good to go.



C



On Jan 23, 2024 7:48 PM, "Amp Guy Llc via groups.io" <kb1sel@...> wrote:
But you said the coil alignment procedure is in the manual , I must have missed it. Do you know the page number.?

Once the pa is working , I strongly suggest selling. Take the money and run

You talking about Paul ?

Some guys change the cap values to shift the resonance point on the l1 and l2 coils, after they have put a pit in the coil or the shaft the wheel rides on. So the wheel ends up in a different spot on shaft and coil.?

The c1 fixed ceramic doorknob caps love to arc to the chassis and to the shorting flappers in the middle which are at ground potential. Turns into a real mess. The microy material is fun to obtain and then have machined.?



Amp guy llc
Amprepairguy.com
YouTube Amp repair guy
203-892-4119

On Jan 23, 2024, at 8:26 PM, W7WRX <clark@...> wrote:

?
Mine is the latest version.? I am friends eith the engineer that revised the tank and door knobs to gain efficiency on 8k.? We face timed and had the covers off his amp and mine and compared them.??

I think Jim must be talking about something else.? No way in hell an ameritron AL 1200 or 1500 does 50 db down. The manual shows -34 BEST case on best band.??

I got my 2 tone setup now and ran the radio to verify.? I will two tone the 8k and see what it shows. I wanted this data before adding the input.? I was using a carrier prior and just looking at the spec an lightly coupled. No attenuator.??

In any case the tuned input board reduces the harmonics by at least 20DB and can be as much as 30.?

Now Jim, what the heck are you talking about brother?? How are you testing to get -50 out of an ameritron?? ?You certainly can't be talking about IMD????? Confused...

C

On Jan 23, 2024 4:02 PM, "Amp Guy Llc via groups.io" <kb1sel@...> wrote:
On what page of the manual does the book show alignment of the inductors . Ted Henry nor anyone worse I talked to at Henry radio had any clue, ?10 plus years ago . Also had no records of revisions ?they had done.?

I was rebuilding / fixing for re sale?

Ka1cde pat , was nice enough to let me come up to see his , to copy . As his was one of the last ones made , and was the most current version with all updates.?

Amp guy llc
Amprepairguy.com
YouTube Amp repair guy
203-892-4119

On Jan 23, 2024, at 12:21 PM, W7WRX <clark@...> wrote:

?
The board has a pass-through trace if no relays are selected.? RF in and OUT.? As you select a single relay, it pulls the contacts off the jump trace and places the inductor in series.? The caps go to ground. Simple.

I was just testing the board into the amp. I understand that it will be different once installed and that Unun mess is removed.

I read online that you should use the .01 coupling cap when making your bench settings.?

I tried this and found no difference on any band.? ?There is a page online where a man shows how the coupling cap effects it with graphs. I think he had something else going on.?

Its very hard to believe the -50 figure.? That seems out of the range of reality.? ?I have measured dozens and dozens of amps here and most are -29 to -32 DB range using a radio that is -45? The only two amps that are better are my 4cx10000D, which is showing -60DB down as good as the rig and my Collins 30S1 which shows in the -45 range.?

Remember, I was NOT using a Two-tone generator for my tests that I posted for the 8K. I was simply using a RTTY carrier with the Spec An loosely coupled.? ?

I was just trying to see if the board was in fact working on all bands and trying to see how much its going to lower harmonics as I tuned each band.

I also wanted to see if the inductors would heat with a 100W RTTY carrier through them. They dont.? They run cool and imagine how much air will be on the board near the tube socket.

Once I install the board, I can run a two-tone proper test and see how the overall amp performs.? It's dirty now. Real dirty.??

One thing I will circle back on is the adjustment of the LOAD side inductor in the 8k ultra.? ?Peter got me thinking.

The book shows how to align the big roller and the load side roller.? I was told by a man that worked for Henry on the 8k to adjust the load coil for max output.??

To do this you tune the amp on 20 meters,? Derail the chain and manually adjust the Load inductor for max output.? I did this with a tuning pulser and found 1000w!!! more output.? ?

I am now thinking of resetting it and testing the harmonics again to see if this throws off the network.??

Unfortunately, I was in the hospital over new year's and they found a herniated disk in my back, A growth on one disk and a problem in with my SI on left side.? I have been in massive pain and started physical therapy.? I don't think it's a good idea that I pull that RF deck right now. I am going to have to wait a bit and get a friend over here to help me yank it!?

C


From: [email protected] <[email protected]> on behalf of Jim VE7RF via groups.io <jim.thom@...>
Sent: Tuesday, January 23, 2024 7:25 AM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Tuned input
?

Clark, does the tuned input board have some sort of bypass mode ??? ? It would require one extra relay to pull that off.?
With relays wired correctly, only one relay is ever energized....(for whatever band it's on).? ?With no relays energized, the xcvr should see a wide open.? ?

?

If the output of the tuned input board is feeding that back to back un-un mess, that could easily screw things up.? You might want to at least temp bypass the 3 x un-uns and the relay that switches the back to back un-uns to the single un-un. Then retweak the Arco's.? If all is well, then remove the mess of un-uns + their relay.? Then feed the output of the tuned inputs....to the cathode..via the oem henry 4 x paralleled? .01uf coupling caps.?
A .01 uf coupling cap should not affect the tuning.? .01uf = 10,000 pf? =? 8.84 ohms of XL @ 1.8 mhz? = dick, non issue.? ?4 x .01uf caps in parallel = 40,000 pf =? 2.21 ohms of XC @ 1.8 mhz? = less than dick.?

Typ kw PI network on the output side is down 50 db for 2nd harmonic suppression.....and even more with a PI-L.? With the un-un mess bypassed / removed, you will probably see a big improvement.?

In the high gloss? Eimac catalog, they state IMD3 for the 3CX-3000A7? is -53dbc (-59db pep)...and that's at 5 kw pep out, using their 2 tone test.? ? It's one of the cleanest tubes in the entire catalog.?


Jim? ?VE7RF

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