PS without amp sampling

kknickelson
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PS without amp sampling

Postby kknickelson » Sun Aug 15, 2021 9:57 pm

I don't have the coupler to sample my signal out of amp.
Been using PS and I know my signal looks good on my pan adapter during TX.
Without PS signal not looking good.
Would like to hear your thoughts on this.

Thanks,
Kevin
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K1LSB
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Re: PS without amp sampling

Postby K1LSB » Sun Aug 15, 2021 10:23 pm

Same here. I read on one of these fora that the Apache Labs design team assumed that most folks would run PS nearly all the time anyway, which I do myself, and in that case it doesn't really matter how dirty things look without PS because PS tidies up the signal much cleaner than any other signal on the air.

Mark
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kc2rgw
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Re: PS without amp sampling

Postby kc2rgw » Mon Aug 16, 2021 12:38 am

I run it all the time, one amp works well with the coupler output, one does not. With the one that doesn’t work well, I simply run PS on the local loop back. Over the air there is no distinguishable difference. It is the cleanest signal you will see on the bands.

If it bothers you when it hunts around, just do a ‘one shot’

Go to frequency

Tune antenna

Go to dummy load

Bring up the Linearity dialog and hit the PS-A button to enable it.

Set your max drive level from the Anan

Hit two-tone in the linearity dialog, when PS-A finishes adjustment, hit the single shot button on the linearity dialog

Hit two-tone to stop sending it

You are all set for that band and any drive level the same or lower than you just set up for.

If you switch bands or increase drive level, just do the one-shot again.

This sounds worse than it all is once you do it a few times. It’s just my tuneup routine when I switch bands.
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w-u-2-o
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Re: PS without amp sampling

Postby w-u-2-o » Mon Aug 16, 2021 2:00 am

Unfortunately, if you are running with a configuration where you are only linearizing the ANAN hardware and not the amp, the DUP display is somewhat misrepresentative, and your over-the-air signal, while improved by the amount the PureSignal can linearize the ANAN hardware, is still nowhere near as good as it looks on DUP.

Remember that DUP shows what RX1 is receiving when your are transmitting. Without an external coupler appropriately configured and selected for both processing by PureSignal and display by the DUP (full duplex receive) function, you are only seeing what is coming out of the ANAN hardware on the DUP display. PureSignal, and RX1, are both using the internal coupler. Linearization only happens to that point, and DUP is displaying that, and of course it looks fabulous because PureSignal does a great job. But whatever non-linearity remains in the amp, and it can be quite a bit, is still going out over the air, and is not visualized on the DUP display in that configuration.

If you have an external amplifier it is highly recommended you equip with a coupler of some sort.
kknickelson
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Re: PS without amp sampling

Postby kknickelson » Mon Aug 16, 2021 12:48 pm

Thanks for the replies.
Scott do you have any recommendations for couplers?
I normally run about 600 to 700 watts.

Kevin
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w-u-2-o
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Re: PS without amp sampling

Postby w-u-2-o » Mon Aug 16, 2021 1:19 pm

The Xtronic couplers are, by far, the best value and best performing choice for amateur radio. Unfortunately they seem to be unobtanium right now.

People have successfully used the the couplers that come with the Telepost LP-100 and LP-500 power meters.

The best "pro" level, high power HF couplers come from Werlatone and MCLI. I've used both in my work but they will cost you a mint!

There are a lot of plans for home-built couplers. Just google "high power HF coupler". However they can be hard to get right if you don't have some lab equipment to test them. That said, NanoVNA test units (official site, but there are a zillion of them on Amazon) are dirt cheap and fun to use!

I would steer you away from the "samplers" sold by Clean RF. They are fine for their intended purpose, which is to drive an oscilloscope display, but they are dangerous to use for PureSignal because their output can easily exceed the +13dBm input power limit of the ANAN hardware.

Be sure to read this thread: viewtopic.php?f=20&t=2384
DO2ZA Erwin
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Re: PS without amp sampling

Postby DO2ZA Erwin » Mon Aug 16, 2021 3:24 pm

Hi All,

also this homebrew Sampler work very fine

https://sites.google.com/view/vk1hw/hom ... rf-sampler

Greetings Erwin
Anan 7000DLE MK2 black, P.2 v2.1.18, WIN 10, 10.0.18362 (1903), i7-7700 @3.60 Ghz, 2x Monitor 24"@144 Hz and 1x 32" Monitor @120 FPS for Thetis
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Re: PS without amp sampling

Postby K1LSB » Mon Aug 16, 2021 4:05 pm

Kevin,

I built my own pure resistive non-directional sampler (I have no need for a directional sampler) from a handful of 2-watt 12k-ohm carbon composition resistors and a Hammond 1590C enclosure box. Total resistance at the tap is 18k-ohms. Not sure what that equates to in terms of dB attenuation but it works fine for any power level between 25 watts and 1 KW (all my AL80B can deliver). I decided to go with a pure resistive arrangement to avoid any capacitive or inductive reactance influence to the PureSignal algorithm.

Here's a link to several pics I took of that project. Disregard the variable pots in the enclosure (those were installed for development purposes and are no longer part of any circuitry), and you can probably also disregard the smaller resistors in the circuit as they make a negligible difference in the 18k-ohm value of the total resistance.

https://drive.google.com/drive/folders/ ... sp=sharing

Basically it's three pairs of parallel 12k resistors (each pair being 6k equivalent) connected in series, so the total series resistance is 18K (3 times 6k). I determined empirically that 18k served my purposes well, and left plenty of attenuation headroom still available in Thetis to run full legal power if desired (if I recall correctly my PureSignal auto-attenuate level in Thetis is 18dB at a transmit power level of 1KW using that sampler).

Another 7000DLE MKII user in the area asked me to build him a box just like mine and he's plenty happy with his. Here's a pic of his installed in his shack, he's running at least a KW:

capture.jpg
capture.jpg (234.68 KiB) Viewed 7072 times

Mark
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KA5KKT
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Re: PS without amp sampling

Postby KA5KKT » Mon Aug 16, 2021 7:39 pm

If an amplifier has an RCA PS connection is that an idication that it has the appropriate feedback ciruitry built in and thus no need for a directional coupler?
K1LSB
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Re: PS without amp sampling

Postby K1LSB » Mon Aug 16, 2021 7:55 pm

Yes.
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w-u-2-o
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Re: PS without amp sampling

Postby w-u-2-o » Mon Aug 16, 2021 9:39 pm

KA5KKT wrote:If an amplifier has an RCA PS connection is that an idication that it has the appropriate feedback ciruitry built in and thus no need for a directional coupler?

Maybe. Which amp are you thinking of?
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KA5KKT
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Re: PS without amp sampling

Postby KA5KKT » Tue Aug 17, 2021 2:34 am

w-u-2-o wrote:
KA5KKT wrote:If an amplifier has an RCA PS connection is that an idication that it has the appropriate feedback ciruitry built in and thus no need for a directional coupler?

Maybe. Which amp are you thinking of?


SPE Exoert 1.5K
Last edited by KA5KKT on Tue Aug 17, 2021 2:37 am, edited 1 time in total.
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KA5KKT
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Re: PS without amp sampling

Postby KA5KKT » Tue Aug 17, 2021 2:36 am

w-u-2-o wrote:
KA5KKT wrote:If an amplifier has an RCA PS connection is that an idication that it has the appropriate feedback ciruitry built in and thus no need for a directional coupler?

Maybe. Which amp are you thinking of?


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oe3ide
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Re: PS without amp sampling

Postby oe3ide » Tue Aug 17, 2021 9:38 am

The Expert 1.5k (stock) does not have the feedback output. Also we would expect SMA instead of RCA.
RCA is normaly used for keying and ALC.

73 Ernst
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Re: PS without amp sampling

Postby K1LSB » Tue Aug 17, 2021 9:47 am

Per the SPE Expert website, the 1.5KFA does have a "Predistortion -60dB output sample port."

https://expertlinears.com/1-5kfa

Mark
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oe3ide
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Re: PS without amp sampling

Postby oe3ide » Tue Aug 17, 2021 9:54 am

K1LSB wrote:Per the SPE Expert website, the 1.5KFA does have a "Predistortion -60dB output sample port."

https://expertlinears.com/1-5kfa

Mark


You're right. No info about that on the company's website (spetlc) ... only mentioned in the user-manual.

73 Ernst
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w-u-2-o
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Re: PS without amp sampling

Postby w-u-2-o » Tue Aug 17, 2021 11:39 am

The first generation 1.5K-FA did not have the coupled output. The second gen. units do. Be mindful of this if you seek to buy a used one.

There is better info at the main SPE Italian web site:

http://www.spetlc.com/en/products/expert-15k-fa-uk.html

Even their photos are old and don't show the output. But the manual shows an SMA connector.

It is unfortunate that SPE chose to use a -60dB coupling factor. While this will work fine at full power, if power is reduced below 700W PureSignal performance may begin to degrade for lack of feedback signal level. A -50dB output is better for a 1500W amp and provides the option to pad it down if desired. However, how many people run their amp at less than half power? ;)
W4WMT
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Re: PS without amp sampling

Postby W4WMT » Thu Aug 19, 2021 9:40 am

Hi All,

Just for the record, you also have this option from a couple of retired Tektronix engineers:

https://preciserf.com/shop/ddc545-dual- ... l-coupler/

It's a hundred bucks more than the popular one from Xtronic, but it's readily available and is built really well.

73, Bryan W4WMT
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w-u-2-o
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Re: PS without amp sampling

Postby w-u-2-o » Thu Aug 19, 2021 11:00 am

Good link, Bryan.

Looking at that same preciseRF website, you could use this instead for a lot less money:

https://preciserf.com/shop/hfs-1-5/

But you will need to add a 1W rated, 20dB attenuator on the output. Those are plenty cheap on eBay.

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