Antenna thread

[Llew]

A use for a spare SUP-2400 I had lying around (using a Hughes 18.2-18.8 now).

With its internal tin box eviscerated, an LNA4ALL just fits inside to make a compact assembly ready to fit onto my antenna.

A 10uH coil has been fitted to the LNA to enable it to be powered via the cable from the dongle, although at this stage the voltage will be injected from a Bias-T, further up where the cable comes in to the spare room upstairs before going down to the PC in the living room. A dongle will be modded for this soon.

 

[Vipersan]

Excellent job Llew ..very impressive..

..actually thinking of repurposing my spare SUP ...but for a different purpose ..
As a downcoverter for 1.5ghz..


Annoyingly there already exists a suitable downconvertor ....designed for use with Outernet ...
but can you buy it ?
search as I might I can't buy one..

Testing a Prototype of the Outernet L-Band Downconverter - rtl-sdr.com

 

[Llew]

Yes, they might as well have a use, rather than lying around gathering dust.

The circuit board is very well bonded to the can - I had to use a flame gun to unsolder the many places it's attached. Much fun was had watching the components drop off the board as they succumbed to the heat

 

[Vipersan]

Whilst I have you online Llew ..
I also ordered a while back the new modded RTL dongle ..

Is yours one of these ?


Claims ..
TCXO ..1ppm
Data sample point on pcb ..
Prototype built in Bias Tee
Metal cased ...for screening and cooling ..

SMA end mounted RF input connector replaces MCX ...
updated V2 RTL chip

ordered from China ..so will hopefully be in transit ..atm..
and cost little more than the original

I know you can get them in the UK now ..but at £24 each ...as opposed to £13.50 delivered from China ..
I'll wait and save a tenner..

 

[Llew]

No, mine's just a vanilla NooElec R820T2, nothing fancy. Where did you order the new modded one from VS?

 

[Vipersan]

No, mine's just a vanilla NooElec R820T2, nothing fancy. Where did you order the new modded onec from VS?

I'll nip home and copy the link for you mate ..
be about 5 minutes ..

 

[Vipersan]

Here ya go ...
Buy RTL-SDR Dongles (RTL2832U) - rtl-sdr.com

 

[Llew]

Thanks for taking time out to post that. Good site that, seem to remember seeing that page before, but must have lost track. I'll put in an order, cheers.

 

[Vipersan]

So ..another flash of perspiration today ..
I have in my posession a 20db LNA which required an external supply voltage between 3 and 6v ...
Not an LNA4ALL ....though this too would fit though the smas might need moving & resoldering to allow it to fit ..
The LNA however has had a 10uH inductor added to allow 'phantom' power over coax ..
I want however to weatherproof and RFI proof this 20db LNA ...
Then it hit me whilst I was working today ..
A small section of 28mm copper pipe ...which I already had ...and a quick visit to the plumb centre to pick up a couple of stop ends ...
real cheap at 99p each ...
et voila ..
I now have a suitable 'container'
(see pics)
the stop ends will be drilled to allow the sma connectors to poke through ..and a couple of nuts to secure the whole assembly ...
this when completer could be glued ...or soldered ...both of which will make later access difficult ...so will wrap a piece of self amalgamating tape round it ..
This will be my ABSB pre-amp ...so will mount outside ..thus the need for shielding ..
rgds
VS

You know I like to name things ..so this will be known as the 'Suppository LNA'

 

[Vipersan]

All Done ..
Neat innit ..
;)

 

[Llew]

Very neat VS, bombproof. +1 for the name ;)

My LNA4ALL is now at the antenna head, getting >100 flying machines now.

Had some hiccups providing phantom DC at the correct current level to the device. I needed to lower the current limiting resistor to 47R from 100R in my Bias-T design, as it was only providing 40mA at 4.5v to the LNA4ALL over the extended coax. It's now 6V at 60mA. I really need a decent power adapter for the Bias-T, instead of the usual rubbishy unregulated ones I seem to have dozens of.

 

[Vipersan]

Very neat VS, bombproof. +1 for the name ;)

My LNA4ALL is now at the antenna head, getting >100 flying machines now.

Had some hiccups providing phantom DC at the correct current level to the device. I needed to lower the current limiting resistor to 47R from 100R in my Bias-T design, as it was only providing 40mA at 4.5v to the LNA4ALL over the extended coax. It's now 6V at 60mA. I really need a decent power adapter for the Bias-T, instead of the usual rubbishy unregulated ones I seem to have dozens of.


View attachment 94267

Hopefully your new RTL dongle with built in Bias T / Phantom coaxial supply will sort this out also..
rgds
VS

 

[Llew]

Yes, that's worth waiting for, so I'll hang fire instead of adding filtering, smoothing to the adaptor O/P.

 

[Vipersan]

Today I thought I'd have a crack at making a quarter wave dipole centre frequency around 129 mhz for Airport coms etc ..
So ..a combination of plastic plumbing and 15mm copper pipe with capped ends ...and a homebrew balun on the support bar ..
Pics are below ..
not tested as yet ..but I am hopeful..
The tricky bit was reducing the 22 plastic overflow T to carry the 15mm copper elements ...
This was done with my old friend liquid plastic

rgds
VS

 

[Vipersan]

Still not tested yet ...but have sorted the PL529 connector issue which will make this detachable ...
I have no doubt that the upvc upright will not be strong enough ..so may well use 22 mm copper for the mast ...
but ..you get the idea..
Very pleased with my design ..
Fingers crossed it responds well at the chosen frequencies..
rgds
VS

 

[Vipersan]

Tested and working very well on my Uniden UBC9000XLT bearcat scanner ...
will try it on SDR later ..

 

[Vipersan]

Finally the weather relented ..and so was able to get my dipole up ..
pix below..
rgds
VS


better keep an eye out for pikeys with ladders ..
Its mostly copper ..
lol

 

[Vipersan]

Finally the weather relented ..and so was able to get my dipole up ..
pix below..
rgds
VS
View attachment 95708 View attachment 95709

better keep an eye out for pikeys with ladders ..
Its mostly copper ..
lol

Wot no viagra jokes ????

 

[Vipersan]

Despite the lack of brightness today ...and feeling well below par ..I got a new project started ..
A new Tripod for Christina ...
This time with M6 bolt fixings at the ends ...and once again made from 15mm copper pipe ...
Also constructed an aluminium letter box frame to carry 3 lnbs ..
one at focus ..and 2 other offset a couple of degrees ..
This is as far as I've got today ..
more to do ...
;)
rgds
VS

 

[Vipersan]

Dont you just love playing out in the sun ..
It never gets old ..even in yer late 50s ...
Time to relax for an hour now ..having taken the day off work ...and got 2 tripod brackets made and fitted ..

Using M6 ball joints plus ally strip and rivets..