Skip to main content

Chinese connectors N-SMA , 23 January tropo

Last microwave meeting Heelweg, 


I wanted to test my 23cm LNA  MMC SKY67151
https://vhfdesign.com/lna/lna-23cm-sky67151.html
Like picture below but N connector version .
The older type below has a bandpass 100MHz / -3db  exellent results low noise
high gain no self oscillation no more 4G interference.
The newer type has 20MHz bandpass a HAM friend wanted my old to use it for 23 ATV
And i got a new in return
Needed   N-SMA adapters since my tiny XVTR box at the dish uses SMA type relay
The pre-amp / XVTR is direct at the dish.
I got 2 "Chinese" N-SMA with it
The measure crew at the noise figure stand told me right away you can throw this N-SMA in the bin...
But please measure first and judge then..
It was found that the suspect adapter is not bad at all
 adding about only 0.1dB to the noise figure.
That is a normal insertion loss for a connector.
A brand adapter Amphenol  offered 10€ used but gave no less noise then the suspect.
Then another brand type was found Telegärtner, new the seller accepted 2€
That one was just marginal better.
The noise figure found  little over 0.4dB
Already tested a lot of this LNA's by those men but non reached the 0.3dB n/f .
Some one told me  his LNA was measured 0.3 but at an other measuring setup.
Could be this measurement was conservative... like my own power measurement.
Anyway the cheep eBay connector was as good as Amphenol in this setup.

The newer LNA was tested last week during a period of good tropo  23 January
heard 1296.890 OK0EB
1296.970 OK0EKL  also 24 Jan.  and 1296.827 SR6LHZ  1W  beacon on excellent high locations
no human OK SP heard
Also new active strong beacon is 1296.875 ON0VHF
some DL beacons very loud  1296950.8 DB0GW s9
and a new heard 1296.880 DB0MOT JN40ff
Tropo was selective only S-E QTF

After the week with good tropo the weather changed to normal showers and more wind.
Still i can hear DB0GW weak  a sort of receive Benchmark for me.
It seems beter then or at least the same as before with the first LNA.
But now it seems we change to more winter weather type and 23cm can be put down again.





Labels:

Comments

Post a Comment

Archive

Show more

Popular posts from this blog

2011-01-22 DIAMOND 2m 70cm 1m30 Colinear inside

Having relative poor signals on the local 70cm / 2m channels using this X50 Diamond collinear 70/2  1m antenna at a height of 25m. I needed to investigate what could be wrong. Measuring the cable only 3W is left for the antenna of the 10W 435MHz output from a IC451E The cable is 30m type H100 Z50 10mm outside diameter it is semi air-spaced but has an impossible 4mm² solid CU inner conductor not much air left. I preferred the H43 Z75 cable having lower loss and mechanical better ratio in conductor size. My antenna uses SO239 connector UHF type semi air spaced isolator.  3W should be enough for a comfortable noise free FM signal. But only 27km away at PA0A the signal is weak too weak something must be wrong? I made a simple reference dipole of 2x17cm CU wire. With this dipole the signals where totally worse. So the Diamond does work? I got curious to look inside. Maybe moisture penetration degraded the antenna. This  antenna is rainwater close in its n...
8 comments
Read more

SPF5189z Low noise preamp 23cm

 14-4-2018 updated Above the low noise  preamp 50 - 4GHz    ebay  6€ Tested  2 small porto antennas 1 Baofeng UV antenna left   2nd best signal on PI2NOS 2 eBay DIAMONDSRH805S  wide band 144/432/1200  it works for its size as expected 3 piece of wire :   best signal in the setup... Unit under test at workbench. It was stable  50mA  at 5V   few days,  but sudden the current went up to 100mA And i could  no longer adjust it with the negative bias Voltage. The - Voltage went to zero and the SPF input port became low Z. This SPF5189z was broken  no oscillations, no input overload just it broke while i was receiving the PI2NOS 430.125 using a small antenna at the workbench. The specs of  SPF5189z  say it has an internal circuit  regulating the bias current. Replaced . again   with an other of the 5 spare SPF i have. The new one again could be adjuste...
11 comments
Read more

BIJZEN mast en ontwerp fouten.

In 2013 heb ik een Bijzen aluminium mast 3 x7m  opgehaald  bij iemand die hem niet mocht plaatsen Gemeente Oss  dat zegt misschien al genoeg.. Pas in 2018 heb ik hem geplaatst had ik veel eerder moeten doen. Mooie mast, mijn xyl vond hem zelfs mooi. Hij is licht, de 3 delen wegen  235kg  het vaste deel 102kg dus het te lieren gedeelte weegt   slechts 133kg + ca 50kg rotor + antennes etc.  De elektrische lier is wel erg zwaar 30kg misschien wel maar die zit onder    Antenne  3ele Steppir  19kG  +  G2500DXC rotor: 3.6kg  + rotorbuis 12 kg  +  kabels 10kg  + 5/7 ele 6m beam. ongeveer 50kg Je moet niet te dichtbij  kijken, dan valt op dat het Aluminium lastwerk heel slordig is gedaan, scherpe bramen aan de lassen waar kabels door kunnen worden beschadigd of haken Er is zeer ! weinig ruimte voor de rotor een YAESU G2500DX past net maar dan ook net  met beetje buigen van  kruisverband. Het...
3 comments
Read more