Just Sharing This S Band Down Converter in Useful waterproof box

[s-band]

Even if you don't want to use the S-band innards, the box is ideal for LNAs etc see
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I got one from here: MMDS Aerial Down Converter Antenna Downconverter Amateur Ham Surveilance Chorus
but in the US they are only ~£3 each in 8 off ($lots for shipping to UK). Aliexpress has listings for many versions covering other frequency ranges.

The down converter did what it was supposed to ~2.5dB NF but the phase noise is not wonderful. It is specified 2.5-2.7G but is usable down to 2.4G. It is very easy to change the antenna for a 1" flange socket (I used SMA but N or TNC could also be waterproof). There is a gasket sealing around the antenna/connector flange.

It would also be easy to change the LO a bit by changing the crystal. I haven't tried but it should be possible to modify the LNA to 1.5GHz. The mixer & filters don't lend themselves to moving far.

 

[Vipersan]

Well ..looks interesting and at £10 inc postage ..so bagged one ..using your second link ..SB..

Just hope I bought the right item ...
I'll be watching for your reports on testing and modding it ..

What other frequency ranges are available on Ali ?
I use Ali all the time ..so happy to buy from them ..
rgds
VS
;)

 

[s-band]

... it should be possible to modify the LNA to 1.5GHz.....

The front end peaks around 2.0-2.2GHz (ideal for S band downlinks, non-TV) with a deep notch at 1.5GHz. No reason why it shouldn't be modded but it will take more effort. I think that the front end is an NE4210S01 (a good GaAsFET) and the second stage is a BFG520 bipolar.

What other frequency ranges are available on Ali ?
I use Ali all the time ..so happy to buy from them ..

Search for "MMDS" on Aliexpress

 

[Vipersan]

Blaady hell ...that was quick ..
Only ordered it Thursday afternoon ...and it arrived about 30 minutes ago ..
Popped the lid ...and took a peek inside ..
certainly looks the biz ...
well made and a bit bigger than I imagined ..
Lots of look in there and a nice gasket sealed box ...
I presume the thing on the end is an S band Dipole ?
Looks to be in 3 stages ..
Font End / LNA /mixer ...filter ...and another amplifier ..possibly...with DC supply 8v regulator close by ? ..though I have yet to see a Crystal ..
Maybe on the underside of the pcb ..
Ill remove the other side and take a look..
rgds

 

[Vipersan]

Yep ..as suspected the crystal is on the other side ...and a chip
74HC4046 ...CMOS logic ?
So looks like they use a crystal osc ...and logic gates for the oscillator .../frequecy multiplier ...

This is on a seperate pcb on the underside..
There is also an 8 pin chip
Ident 1507
No idea what this is as yet ?
possibly a PIC ...
S-B ...have you worked out what it is yet ?
rgds
VS

 

[s-band]

I presume the thing on the end is an S band Dipole ?
Looks to be in 3 stages ..
Font End / LNA /mixer ...filter ...and another amplifier ..possibly...with DC supply 8v regulator close by ? ..though I have yet to see a Crystal ..

Dipole encased in plastic with balun. You get a reflector to put on the front. It is designed to fit a mesh dish/grid such that the mounting holes are close to the dish grid.

Line up: NE4210S01 (a good GaAsFET) and the second stage is a BFG520 bipolar, filter (2400-2700 and a bit lumpy), single balanced mixer, LPF, one or 2 IF amp stages (can't remember)

74HC4046 ...CMOS logic ?
So looks like they use a crystal osc ...and logic gates for the oscillator .../frequecy multiplier ...

This is on a seperate pcb on the underside..
There is also an 8 pin chip
Ident 1507

4046 is the phase detector
1507 is a UPB1507GV pre-scalar set to /256
Xtal osc & VCO are bipolars

 

[s-band]

I ordered another from Aliexpress specifying 1998MHz LO, 2.1-2.3GHz & high gain (34dB ). It arrived in 10 Days. It was dirty & smelly (bitumen or something like it). Inside it was similar to the Ebay one except it had been hand bodged to tune it down and looked quite messy. The antenna was bent but I don't need that part. The front end is an ne3503m04 instead of the NE4210S01. I wasn't expecting much but it works well. Gain is OK and NF is better than 1.5dB (not a very accurate measurement done). It covers about 2080-2350MHz with reasonably flat response. The LO is ~20-30kHz high depending on temperature. Theres a bit of a notch at 2400MHz but it still works up to about 2500MHz although I didn't check NF up there. The image rejection to ~1900MHz is only about 20dB so it could suffer if there were a nearby cell but it is about 30dB by 1750MHz. On the analyser, 2.1G cellular is loud and the usual mess 2.4-2.48GHz was present.

I made a 2ish turn LHC helical to give RHC on the 1.5PF dish. It's attached to the C band scalar so probably a bit too close to the dish face for best focus. The easiest signals to identify were Meteosat at 9.6E, 3.6E, 0.4E & 3.2W. I think I found a CW beacon for TDRS at 12W. I thought I found some of the Skynet beacons at various positions but could not convince myself that they were not terrestrial signals. There are a few signals that I couldn't identify including the one around 9W shown in the plot below. The other plot is MSG 2, 9.6E.

Not bad for $24 delivered + a piece of bent wire.

 

[Vipersan]

..I shall be putting one on my shopping list soon ..
Certainly looks interesting SB