Auxiliary equipment for various GHz measuring purposes

- Juli 25, 2025

Auxiliary equipment for various 10,0.....13,0 GHz measuring purposes - Output power max. 1mW

This is an UP and DOWN mixer, meaning it can downmix 10GHz signals to for example 1GHz and UPmix 1GHz to 11GHz. Thus, the IF port output and input are the same as the RF port input and output.

PLL oscillator from: DF9NP https://www.df9np.de

Mixer : Hittite https://www.analog.com/media/en/technical-documentation/data-sheets/hmc220.pdf

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2 Ports VNA KC901R

A very good measuring device for measurements up to almost 10 GHz. Despite the stated range

of 7 GHz , it actually works up to over 9.8 GHz with all its functions. In addition to the RF analyzer

and RF signal generator ( including an AF generator ) , measurements of S11 S22 S12 and S21 are also possible.

https://deepace.net/wp-content/uploads/2020/10/KC901S-User-Manual.pdf?srsltid=AfmBOopfR0QiIXCBj4jj6NpTAdl5YZx8c06JGzIepV1s62TTVFgxWGOj

https://deepace.net/product/measall-dual-ports-handheld-network-analyzer-kc901r

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Digital Ampere Meter for special current applications

...built with affordable DSN-VC288

Why did I build this ? As an example, I'll show you the problem I had...

Before the amplifier turn ON , i have to set the quiescent current, according to the data sheet 1400mA at Vdd 6 Volt.

1. remove R16 0 ohm

2. take a multimeter and in position 2A connect with plus

and minus

3. Then, with the operating voltage switched ON, the

quiescent current is adjusted using the ADJ trimmer.

Now there is another problem, none of the multimeters

can measure 2A max, they are either built for 200mA or 20A or 10 amps.

OK , then in 10 amp position !!!

Quiescent current set 1400mA , R16 soldered again 0 ohms , and put into operation. But that's not correct the quiescent current is almost 1500mA. Why ?

Did you know that an ammeter has a resistance of 0.1 ohms and that at higher currents the value is even higher with a cable.

As it was set, it was relatively OK but as soon as the 0 ohm resistor was put back in everything changed again.

Why ?

There is a shunt in the measuring device and it has a resistance ( otherwise it would not be possible to measure ) but there is also a resistance in both cables themselves , which is particularly bad when higher currents flow through unsuitable cables. When you purchase a multimeter, you'll receive a black and red test lead.

As a customer, you'll think both leads are suitable for all measurements with this multimeter (even for 20A).

The cables also look good, nice and thick, and give no cause for suspicion. The cables are also suitable for all measurements, including currents up to 200mA. Why only up to 200mA ? Well, that's because...

With a diameter of 3.7mm, the cables look nice and thick, but unfortunately the inner conductor is much thinner and unsuitable for 10A current ( needless to mention 20A ), but also not for 1.4 amps.

" Copper is expensive = manufacturer wants to save "

With 2m measuring cable length and 1.4 Amper current, voltage has dropped by almost 0.4V (instead of 6V only 5.6V)

This was the reason why I had two different quiescent current values with and without 0 ohm resistance. The voltage drop on the test cable was too high due to the resistance in the cable.

Since the connections in the multimeter are also not entirely suitable for 20A current, I decided to build my own Ampermeter with really thick connections and flexible cables with a 2mm inner conductor diameter.