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MAX2870 by ADF4350


Daniurkys Otero Reye 2020/12/05 00:11

Greetings, I have been analyzing the dynamic range of the nanovna v2
plus 4 and this exceeds the nanovna-f since it has two ADF4350s to
increase said range without the need to use harmonics, excellent
always works on the fundamental, but my humble opinion is, perhaps
MAX2870 could not be used by the ADF4350 and so enthusiasts,
experimenters of the 5Ghz band could experiment with the nanovna v2
plus 4

Kadir Mariño Abreu 2020/12/05 13:57

Greetings, Daniurkys although it can also be the MAX2871, which I do not know what is the difference between them, 70 and 71.

Kadir Mariño Abreu 2020/12/07 07:34

It would be great to be able to work with more than 4Ghz, mainly in the 5Ghz band, although it would be a bit difficult to build the SWR bridge at such a high frequency, if a bridge with minimal requirements is not achieved, at least one solution would be to program in the firmware up to a certain frequency where said bridge works acceptably, and the remainder of the bandwidth of the Max2870 / 71 would be used for the measurement of the different band filters, is my humble opinion.
Let's see if someone else can comment on this issue in more depth, in my opinion it would be great, I reiterate since for lovers of the 5Ghz band and Wi-Fi experimenters in that band, an instrument of this type would be very useful, thank you.

Jim Lux 2020/12/07 07:53

On 12/7/20 7:34 AM, Kadir Mariño Abreu wrote:
> It would be great to be able to work with more than 4Ghz, mainly in the
> 5Ghz band, although it would be a bit difficult to build the SWR bridge
> at such a high frequency, if a bridge with minimal requirements is not
> achieved, at least one solution would be to program in the firmware up
> to a certain frequency where said bridge works acceptably, and the
> remainder of the bandwidth of the Max2870 / 71 would be used for the
> measurement of the different band filters, is my humble opinion.
> Let's see if someone else can comment on this issue in more depth, in my
> opinion it would be great, I reiterate since for lovers of the 5Ghz band
> and Wi-Fi experimenters in that band, an instrument of this type would
> be very useful, thank you.
> _.


It's not the bridge that's the hard part - most modern VNAs just use a
resistor network of some sort. It's all the other pieces, oscillators,
amplifiers, and detectors.

The NanoVNA and NanoVNA2 both make clever use of very few inexpensive
components. The Maxim parts you mention solve only part of the problem.

If you don't need low frequencies, then one of the new parts like the
AD9361, which goes up to 6GHz, but only goes down to around 100 MHz
would work. You could probably use just that part and some sort of
microcontroller since it includes the PLLs, the mixers, the amplifiers,
and the ADCs. The problem is that those parts are pretty expensive -
$175 in Qty 1000.

I suspect that one could probably build a VNA using a couple of ADALM
PLUTO modules (which use the one channel version of the AD9361) if you
could sync them. But that's still no display or controller, and you've
already spent $200 (if you get the discounted student price).

To sell something for $100, the Bill of Materials cost needs to be less
than $20. That's quite a challenge.

Reinier Gerritsen 2020/12/07 18:03

I do think the bridge is the main problem, not the resistors but the
balun that converts the differential bridge voltage to a single ended
signal. Also the mixer may need to be replaced. It is specified to 3.8 GHz.

Reinier

Op 7-12-2020 om 16:53 schreef Jim Lux:

Kadir Mariño Abreu 2020/12/07 09:07

Greetings Jim Lux, you are absolutely right, the instrument would be a little more expensive not only because of the chip with a wider dynamic range but because of everything else that you mentioned that it would take, but it does not hurt that a version will be launched with a range of up to 6Ghz, although this was a little more expensive, because I think that the ADF43XX-X chip series (for example the ADF4355) have a range of more than 6Ghz, thank you very much for your comment.

amirb 2020/12/07 09:10

as Reinier pointed out, the bridge is indeed the main issue.
I would say even the design of the resistive bridge (not to mention the balun part as Reinier correctly points out) is problematic
when you want to get to 6GHz. Lots of parasitics must be carefully accounted for or you will be way off at the end...

the synthesizer and mixing parts are pretty easy and cheap. tons of choices out there, take your pick
and the layout design is not that difficult and it is even given out by the chip manufacturers
max2870 seems a good choice and not expensive at all. i haven;t dived into the details of specs though...

Kadir Mariño Abreu 2020/12/07 09:19

Reinier Gerritsen, if you're right, the mixer could be, for example, the M810 (IAM-81008 or IAM-81028). I don't know what you think?

OwO 2020/12/08 01:20

Actually the biggest problem is simply market size - the number of
people that really need 6GHz and isn't already well served by the
existing V2 options is small enough that you ought to sell it at pretty
high prices to begin to make back development costs.

It already exists - just a month ago Arinst released a new two port 6GHz
VNA (search "arinst VNA-PR1" on Aliexpress), and at the same price their
one port VNA used to sell at. Considering it has 70dB dynamic range at
6GHz I would say it's good value already.

Reinier Gerritsen 2020/12/07 18:37

The Arinst VNA-PR1 is not a full 2 port VNA. Just like all Nano
variants, port 2 is just a receiver port. Too bad...
Reinier

Op 7-12-2020 om 18:20 schreef OwO:

Kadir Mariño Abreu 2020/12/07 10:16

Not bad at all (Portable 2-Port Vector Network Analyzer Reflectometer Arinst VNA-PR1 1-6200 MHz With Touchscreen) https://www.aliexpress.com/item/1005001738222447.html
but I like the way of construction and performance of the V2 PLUS 4 more, that is why I asked if a version could be made by changing the ADF4350 for the MAX2870 / 71 or another with the same similarity, and also using the combination together with the Si5351 to cover from 50Khz onwards.
It is true that everything depends on several or many factors but it never hurts to give a suggestion, thank you very much to all. 73 CM3KMA.

amirb 2020/12/07 10:21

On Mon, Dec 7, 2020 at 12:37 PM, Reinier Gerritsen wrote:

>
> The Arinst VNA-PR1 is not a full 2 port VNA. Just like all Nano
> variants, port 2 is just a receiver port. Too bad...
> Reinier
>
> Op 7-12-2020 om 18:20 schreef OwO:
>
>> Actually the biggest problem is simply market size - the number of
>> people that really need 6GHz and isn't already well served by the
>> existing V2 options is small enough that you ought to sell it at
>> pretty high prices to begin to make back development costs.
>>
>> It already exists - just a month ago Arinst released a new two port
>> 6GHz VNA (search "arinst VNA-PR1" on Aliexpress), and at the same
>> price their one port VNA used to sell at. Considering it has 70dB
>> dynamic range at 6GHz I would say it's good value already.
>
>

that's not really a handicap. you can just swap the device backward for s22 and s12
old HP VNAs were the same
one issue I notice is that the resolution above 100MHz is only 10KHz
now I dont quite know what they mean by that although it says it has 1000 sweep points
so how are these two numbers related?

Carlos Cabezas 2020/12/07 19:43

VNA-PR1
https://kroks.ru/upload/shop_1/2/1/1/item_2114/shop_property_file_2114_21220.jpg

STM32H473
Si5351
2x MAX2871E
3x ADL5801
IF at 455kHz, 3 simultaneous ADC. RL bridge directly connected to balanced
mixer with no balun.

El lun., 7 dic. 2020 19:16, Kadir Mariño Abreu <cm3kma@gmail.com> escribió:

Siegfried Jackstien 2020/12/07 18:59

not bad that unit ... but you can buy 8 to 10 v2 for the same price

dg9bfc sigi

Am 07.12.2020 um 18:43 schrieb Carlos Cabezas:

Kadir Mariño Abreu 2020/12/07 11:17

It is a bit expensive compared to the v2 plus, and I did not think that this chip combination was already implemented between the Si5351 and the MAX2871.

Kadir Mariño Abreu 2020/12/07 11:22

They have left me speechless hahaha, thanks to the colleague of the information of the internal image of the VNA-PR1

Carlos Cabezas 2020/12/07 20:38

Block diagram: https://i.postimg.cc/VNWtfSJc/VNA-PR1-Block-diagram.png



El lun., 7 dic. 2020 19:43, Carlos Cabezas <eb4fbz@gmail.com> escribió:

Alberto I2PHD 2020/12/07 22:49

On 2020-12-07 20:38, Carlos Cabezas wrote:
> Block diagram: https://i.postimg.cc/VNWtfSJc/VNA-PR1-Block-diagram.png
>

From that block diagram :



:-):-):-)

--
/*73 Alberto I2PHD*
<<< http://www.weaksignals.com >>>/

Kadir Mariño Abreu 2020/12/07 15:07

Here is the ARINST VNA-PR1 manual

http://www.arinst.net/files/2114-ARINST-VNA-PR1/User-manual-ARINST-VNA-PR1-1-6200_ENG.pdf

Siegfried Jackstien 2020/12/08 07:45

and behing the 3 pga towards the adc the mixer stages are missing ... i am sure the stm32 can not direct sample at 6ghz hi hi
greetz sigi dg9bfc

Kadir Mariño Abreu 2020/12/09 08:10

Greetings Siegfried Jackstien in this link the mixer stages, the ADC and the use of the MAX2871 which is an ultra wideband phase lock loop (PLL) are further detailed, achieving a complete portable VNA of 2 ports at 6 GHz.

http://www.yl3akb.lv/content/vna_v2/vna_v2.php

Kadir Mariño Abreu 2020/12/09 10:40

If the 6Ghz could be done decently for around $ 150 to $ 200 you could even go as high as a $ 250 range, that would be great, not like the Arinst VNA-PR1 1-6200 MHz With Touchscreen which has good features, but is a bit pricey since it's over $ 500. I'm sure 5.8Ghz is where it will spark much more interest from a much wider audience, rather than just radio amateurs. I'll personally be on the lookout to see if launches a version with a capacity of more than 5.8Ghz. Greetings to all 73

Leif M 2020/12/11 08:43

arinst VNA-PR1 costs around 400-500€£$

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