SHL 7008 23cm Power block

[ZL2WHO]

Hi all.
A few years back I purchased this UHF power block https://www.ebay.com/itm/1pc-MOTOLORA-S ... XQLs5RpVxG at around $12nz it was worth the gamble.
A spare hour in the workshop saw me mounting it up and throwing some drive at it from this thing … https://zl2bkc.com/projects/zlpll/
I set test frequencies at 850, 900, 1000, 1100, 1200 and 1300 Mhz. Mr Google found next to nothing but ham in the EU showed that it was a 28v device with an output of about 2.5 watts.

Powering up saw 2.5 watts at 900 and 1G but only 300mW at 1.3G. Not to be out done I grabbed a screwdriver and carefully removed the plastic lid.
Between the two RF devices there is a stripline with a 6p? smd cap to ground located about the middle. I removed the cap and remounted it closer to the output device and to my astonishment I saw 2watts on the bird into 50 ohms with my 5w 1000Mhz slug.

To feed the 1st stage I fitted a 100ohm resistor from the output supply pin (28v) to the driver suppy pin which measured about 18 volts. Feeding this pin with a LM317 between 14 and 18v gives good stable power control from 0 to 2.5 watts.
This is an easy and cheap way to get some good level drive power should you want to start playing with 925 or 1296.

Now to put it into a waterproof box and go stick it on a hill somewhere...

73
Mark
ZL2WHO

[PA0P]

Hello,

The SHL7008 is equivalent to the MHL9236...
You can even reach better success with the MHL9838 and SHL7009 modules. Still available for around $10 on eBAY.
These give you at least 7 Watts of output at 1296MHz.
Just remove the C between the two transistors and add a 1to 2 PF C (preferrable ATC) in the output line close to the output pin.

Another option are the MHW1815 and MHW1915 modules which are also still available for just over 10 dollars.
Modification details can be found on the internet. It takes a bit more work with removing and altering some SMD C's, but you will be awarded with 18 Watts of very linear output. Works great as driver for higher power PA, e.g. 2xMRF286, RF output can be adjusted with supply voltage.

Good luck,

Cor PA0P