I worked an EME VK station in very heavy rain

 

During October , when we had very heavy rain ,I could see a VK station on the Moon.net logger , the moon was just rising in the East just above the terrain .

after chatting i said i would see if we could receive him , it was very heavy rain at the time . I did not

expect anything .  what a surprise he was very strong even though we had heavy rain at the time , that's a surprise , we worked no problems and even got a good signal report in VK land at-13

                         Here is the chat on the logger .

                                                            and the actual qso in JT65B

 I worked my first USA station on EME.

 

 What a signal ! , this is him calling CQ a few weeks later . 

one of the biggest signals on 70cm eme , compaired to DL7APV and HB9Q.

 

                   here you can see the signals ,  decoded and the signal levels.

                   in the recording above the signals reached -9db !.

this is a screenshot of the actual qso in jt65B

 I purchased a 2 meter pallet from OK1DFC Zdenek, 

it's a 1KW LDMOS on a pallet , so I initially fitted it to a large heat sink for testing .

This module is capable of a KW on 2 meters, i tested it with just below 2 watts input to take it to full power . Since I've fitted it into the main amp and purchased a low pass filter , this way was share the PSU, meters etc rather than another cased unit .

still having problems with the main Meanwell psu tripping , it a pain and would trip mid QSO, still no idea why its doing this , i resorted to building another backup PSU using ex server power supplies , connecting te in series to give 50vols at 44 amps.

normally we cant connect the power units together as the negative rail on these is connected to the ground of the case of the unit , this would give a short on the other power units and it would not work.

I found a simple mode was to take out the PCB , the one corner screw grounded the negative rail to earth  so i isolated this , , earth now is just that , not connected to the Negative rail.

I run the amp off this and made some qso, even this amp trips when PTT is pressed , so something is pissing them off as they are quite sensitive . They do reset  , unlike the Meanwell main PSU that i can not use , for a £500 psu its not good.

this is them running the Amp.

Building this power supply was a good learning curve , each unit cost only £12 on ebay , but you take your chances as sometimes you get duff units , i got 8 of them and two proved duff. Against the cost of the meanwell unit its a no brainer .

We have to modify each unit to isolate the earth from the Negative rail on each power supply which is very easy to do, since we are connectiong them in seires we cant have the negative rails connected to the case of each unit .

 Finding the FT847 is drifting , got a kit to make it more stable .

 , it's a heater unit that fits on the crystal.

 

moved the LPF filter in the amp to the top for easy access after it was blowing caps

the FT847 is a bloody good LNA killer I've killer two LNA's , whats happening it puts out a hi power pulse on PTT , the then get to the output side of the LNA as ists switched in to receive, then it blows the saw filter.

Solution is two fold ,i could fit the inhibit mod on the atu. but best of all is to use separate TX and RX lines , there is easy access to the rx input inside the FT847 , so got it coming out on a n SMA connector to the LNA,   Now the RF path goes to the Amp only , on receive the LNA is switched in . I've  added a sequencer from VHF Design as the W6PQL sequencer give problems, it just enables the bias on TX and manages the temperature of the LDMOS devices now, it inhibits tx of the Heatsink get to warm.

luckily my FT847 had a SDR module , but no good for VHF, its HF only.

 New amp in service . In early June 2020

 New amp I Built put into service.

but before we did i managed to work two big guns  with the antenna array and 30 watts for the FT847

very first EME qso in JT65B was with DL7APV

followed by HB9Q as No2 with the new array

I got a screen shot of their signals

 
 DL7APV calling CQ

HB9Q and DL7APV about the same on RX

Build a Ldmos 70cm power amp capable of 1kw on 70cm.

I contacted another ham who had in the UK a W6PQL amp kit that he did not build , so i saved quite a bit getting this and the shipping as the kit came from the USA originally.

Never built one of these before , but i can build most things .

here is the amp during construction.

the dual LDMOS flow solderd to the copper pallet , we had an RF arc during testing ,

the white coax got to hot and desoldered itself producing a powerfull RF arc, extra cooling overt the top of the amp and tuning the amp propery cured the problem.

measuring the matching on hte feed to the amp

Low pass filters, i decided to add anothe band to the amp as there was prenty of room in the case and a large heatsink.

the sequencer

showing the mast head unit with the relays and LNA

front panel

the main 70cm pallet before fitting in the case.

some flash overs on the LPF filters on the 2 meter band , had to move the board top side and give cooling .

you can see the black area where the capacitor let go 

some other issue with the PSU , it trips on times with te RED led coming on the 50v then shuts down , this is a puzzle as it does it even if i remove the PSU from the case and power it stand alone !.

 

normal green

error tripped.