New 10GHz Modules Are In. One Tested.

A little while ago I found some 10GHz modules at an Italian seller on Ebay:

- high gain amplifier, 47dB gain, claimed 26dBm out, covering 4 - 10GHz

- a 10GHz passive mixer module

- a tuneable filter, w/cavities

- a TX up-converter module claimed power output 22dBm

All are announced to be tested, but I should test them all.

Some of those need work, some not:

The high gain amplifier is complete with a single supply and SMA connector, so no mod needed

The IF port connector of the mixer needs to be changed into the SMA type, so I can make decent measurements on it with my test equipment.

The tuneable filter should be re-tuned to 10368MHz

The TX up-converter needs a b it more, but I got started with testing it. It is built with modules mounted on a "sandwich" of 2 PCBs.

First of all. The converter uses a dielectric resonator oscillator, so unmodified it is only useful for wideband applications Specifications:

-70MHz IF

- 10240MHZ output

- DRO tuneable from 10.2 - 10.8GHz, so frequencies above 10270MHz all the way up to the 10500MHz band edge should be possible to generate.

- The mixer output is filtered through a 4 or 5-cavity filter. I suspect it will be tuneable in the whole specified frequency range After the filter there are 2 amplifier blocks:

a) what looks like a single stage amplifier in aluminium casing, probably milled. Likely gain about 10dB.

b) the next amplifier module was opened (Taking the lid off, and contains 2 stages, likely gain: 15-20dB

c)  the specified output of the unit is 22dBm (about 150mW)

- the unit needs both +12V and -12V

Knowing that GaAsFETs need to have the negative gate bias before applying the drain voltage, for "proper use" I will need to make a DC voltage sequencer in order to protect the amplifier(s)

Test equipment:

Recently I purchased two attenuators capable of working on 10GHz, with 10dB attenuation and a 10W rating each. With this I can test/measure up to 1W output without destroying the thermistor mount for my old HP432 bolometer. Since the claimed output is 22dBm/about 150mW this should be no problem for testing the up-converter.

For the initial test the 70MHz exciter is my signal generator, capable of an output level of +5dBm, just what the mixer needs, so the test set-up is:

1) signal generator

2) the up converter module supplied with +12V and -12V, using two 3-cell battery cases with each 3x 18650 cells

3) the two 10dB attenuators daisy-chained

4) the HP432 bolometer with a probe capable of measuring on 10GHz

Here are the initial test results:

Entering +5dBm (70MHz) at the mixer gives 200mW (23dBm) output, so the power specification holds, within the estimated accuracy of my test equipment. changing the IF frequency from the signal generator shows about 1dB higher output at 60 and 80MHz, and about 3dB less around 55 and 85MHz, indicating a filter bandwidth of about 30MHz. Not bad if a higher IF is used.

When changing the IF power level the linearity below 150mW looks good, so with a different local oscillator (synthesizer) there should be no problems running SSB/CW through this up-converter. This is definitely encouraging. A relatively simple 200mW WBFM transmitter using this module with a WBFM modulated oscillator on 70 - 80MHz and using a satellite LNB as down converter should provide a decent basis for wide band experiments with a bit more power than the low cost HB100 module.

This first lab test is a success, More experimentation with this module is in order, but that is foe a bit later. The first of those new tests would be a different LO, and a re-tuned filter, so the module can be used at 10360 or nearby. More to come later.