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I meant the? ultra SA? (4" screen)? and not the nanovna.?

Steve is correct though, my method of? feeding power into a dipole....then picking off the signal with a tiny ant...fed into the small SA, could easily result in some questionable results.? ?IE: dipole has a sky high swr on it's even harmonics...and resonant on it's odd harmonics.... and also have some gain on it's odd harmonics.
Tiny ant? on the SA? will have non uniform response over the freq range in question.?

It was just a cheap and easy way to get a general idea of harmonic suppression.??

What you could do though, is change the scale on the small SA, so the fundamental is higher on the screen....and / or? get the tiny ant closer to the coax...or simply use a bare wire from tiny SA to coax, then wrap around the coax.??

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The original....'tiny SA'? with it's 2.1" screen is incapable of measuring IMD.? The bigger 'ultra SA' ( 4" screen) is capable of measuring IMD..... at least out to IMD7.?

For accurate measurements,? 2 x? xcvrs used, each with a dead cxr....and XXX khz apart in freq.... feeding a combiner. Then into the amp.? ?That or a 2 tone fed into a class A yaesu.? ?Or a 2 tone fed into an ANAN 7000/8000 with it's pure signal on? (xcvr only).?

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What else that works really? good is to feed? white noise / pink noise into the? above xcvr's.? ?

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My problem with the standard 2 tone setup is..... by altering the tone spacing, you can easily skew the results....esp IMD3.?

Next problem with the 2 tone is..... it's all steady state...and nothing is dynamic.? IE: B+, bias, fil V, screen V etc, etc, doesn't budge.?

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From a ..'systems' point of view, just talk on SSB, with xcvr feeding the amp...... and monitor the off air signal with the SA.? If other's can hear your IMD, you will be able to see it on the SA.?

It still astounds me, when? switching from Class? AB to Class A on my yaesu..... while listening off freq on a 2nd? identical yaesu.? Apples and oranges.?

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Jim? ?VE7RF

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Steve You assumed I am an idiot.? Its best to refrain from posts like this unless you know the person.?

You also skipped over the part where I said I dont agree with this and attenuator should be used. Just forgot?? Didnt read it??

The amp is into a Bird dummy load.? There is no antenna hooked up. Thats weird you would assume that.? Who on earth would take measures on an antenna?? Weird.

This is the method Jim uses and I wanted to try it.? ?

The plots DO NOT show anything near -35 DB. You must be blind. The plots show the harmonics are in the noise and not measurable. WITH or WITHOUT the 10,000 watt Key down.

I already posted IMD tests using the ARRL method with my Bench Spec An. I guess again, you just decided to skip over that or ignore that??

Its really best to READ the entire thread before posting like this. You ended up making yourself look bad in public my Friend.


C

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Scott....That's alotta amps! Good option...will likely go in that direction if don't find the plates since nothing simpler than that, 15 minutes and done.
rich

No offense to anyone but I have literally repaired over 1000 Ameritron amplifiers , and built over 100. So I’d say I have decent amount of experience. Which I’m confident to say Jim Thomson will agree on.

I also own a hipotronics hi pot tester which is a real deal piece of equipment . It can be seen in my videos on YouTube

The capacitor I suggested hi pots to 3kv

This is a simple repair , don’t drive yourself crazy

Scott

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No, sorry.

Steve, K0XP

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It's more than a few plates.....rebuilding so simple, so cheap, so still looking for the plates as first choice. You wouldn't know of a source? Tnx for the info tho Steve

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It's more than a few plates.....rebuilding so simple, so cheap, so still looking for the plates as first choice. You wouldn't know of a source? Tnx for the info tho Steve

ok, tnx Louis
rich

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Several points:

a) You cannot make reliable, repeated, calibrated harmonic measurements, especially over a broad spectrum such as to attempt the measurement of high-order products, using a whip antenna on a spectrum analyzer or other receiver; nor by loading a source (transmitter or amplifier) into a "real" antenna. Both the whip antenna, and the real antenna, will act as bandpass filters and attenuate, or even increase, the apparent level of emissions not within their resonant region, especially at low frequencies.

b) The photos showing the tinySA responses showed as little as 25 dB dynamic range on the last photo, and only around 35 dB or so on the first two photos. That means any radiated harmonics, in the last photo, only had to be a little more than 25 dB down and you would not be able to tell they existed; or in the first two photos, the harmonics only had to be down a bit more than 35 dB, and you wouldn't be able to tell they were actually there.

c) The proper way to perform harmonic measurements is to use either a calibrated high power attenuator or a calibrated coaxial sampler into a calibrated dummy load, to obtain a broadband sample of the transmitted signal. The result can then be displayed on either a calibrated receiver or a calibrated spectrum analyzer. All interconnecting cables also have to be calibrated since their loss varies with frequency. For maximum dynamic range on most spectrum analyzers at a reasonable sweeping speed (which is directly dependant upon the analyzer's resolution bandwidth, or RBW) for the frequency range you want, the level of this sampled signal should be no more than -10 dBm, or 100 MICROwatts. Thus, in the cases shown, the signal would have to be attenuated from 10 kW, which is +70 dBm, all the way down to -10 dBm; or, in other words, by AT LEAST 80 dB, in order not to overdrive the spectrum analyzer and cause it to generate internal harmonic distortion products.

Performing accurate IMD measurements is a whole different ball game.

Steve, K0XP

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On Jan 25, 2024 7:01 PM, "W7WRX via groups.io" <clark@...> wrote:

Attached are plots of my 4cx10000D amp.? This is a 10k bird slug with a real bird meter in left side.??

This amp shows no harmonics above noise even at 10000 key down.? ?It's Grounded screen.? Tuned input.? 7500 blus. 1500 screen.

Tomorrow I will test the henry. My back hurts from working all day andnits not hooked up.

C

On Jan 25, 2024 6:56 PM, "W7WRX via groups.io" <clark@...> wrote:

Attached is the performance report for my IC7800 direct from ICOM.? It went back recently for service and they run a new report to confirm its standards.? ?Also are plots using a tiny SA spectrum Analyzer. 200w key down.? You can't see or find any pips or harmonics.? If I use my older yaesu it shows 5 pips across screen.??

The nano vna is a horrible reciever and spec an and should never be used for this measurement. I have expensive spec an but it's in the lab so I grabbed this tinySA.

I will test the amps this way and post results.??

I think the sa should be coupled with an Attenuator for real measurements but this is the way Jim said he does it so out of boredom I tried it.?

C

On Jan 25, 2024 6:48 PM, "Peter Voelpel via groups.io" <dj7ww@...> wrote:

Yes, CW carrier at full power into a dummyload.

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73

Peter, DJ7WW

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

Betreff: Re: [ham-amplifiers] Tuned input

Datum: 2024-01-26T01:12:45+0100

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

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

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Peter with a CW carrier?? Full power?? 1kw?? ? Clearly not two tone.

C

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From: [email protected] <[email protected]> on behalf of Peter Voelpel via groups.io <dj7ww@...>
Sent: Thursday, January 25, 2024 4:35 PM
To: [email protected] <[email protected]>
Subject: Re: [ham-amplifiers] Tuned input

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With a spectrum analyser via an attenuator.

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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]>

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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

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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

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

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Yes, CW carrier at full power into a dummyload.

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73

Peter, DJ7WW

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

Betreff: Re: [ham-amplifiers] Tuned input

Datum: 2024-01-26T01:12:45+0100

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

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

?

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?

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With a spectrum analyser via an attenuator.

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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]>

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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.?