Those 2,7GHz LDMOSes in the Telrad amps are surely performing way better that the 2,17GHz LDMOSes.
73s
Those 2,7GHz LDMOSes in the Telrad amps are surely performing way better that the 2,17GHz LDMOSes.
73s
i have not spended much time on this wire just bended it in a radius that is looks nice.
The PA works with the expected parameters for a modified UMTS pa orginally designed for 2,17GHz.
With 28VDD the current is about 4,4A @ ca. 30W that gives a efficiency of abt. 24% and that's what i expected.
The IDQ was set to 200mA per MRF at first but after the "on air" test the signal stays also at 100mA clean.
EDIT 14.04.20: just discovered that the IDq on the final MRF should be set at 200mA to improve the audio on low transmit power (ca. 250mW)
73s
back in those days only a few hams had a real use for UMTS PAs, so they were really cheap available.
Even that i already had 4 PAs at that time i couldn't resist to buy another one.
Nowadays the prices are a little bit different
73s
Just needed another "small" PA for a fellow OM to reach QO100 with a little bit stronger Signal than with the BU500 alone.
Remembered the Nokia PA i bought abt. 2 years ago on a ham fleamarket (15€).
Cut out the "small" amp (MRF21030 driving a MRF21045) from the PCB, snowflaked and put it in a old PC PSU case together with the BU500 and a fan.
Works good to about 30W pout, clean signal.
73s DB8TF
Keine Sorge, ist ein großer Lüfter dran und die PA ist ja mit bis zu 35dBm im Datenblatt angegeben.
Die Stromaufnahme ist etwa 1A bei voller Leistung. Sollte der interne Schaltregler packen.
Die 500mW waren doch hauptsächlich dem zu schwachen Bandpaß am Ausgang geschuldet.
73s DB8TF
It worked perfect
Never thought that a missing cap on the IF input causes a to high LO level at the output.
Now i can't measure the LO with my old Advantest SA when i generate a 2W signal on 2,4GHz.
This old BU500 is now "up to date"
Next (and final?) step is changing the internal TCXO to a 0,2ppm Murata TCXO.
73s and thanks!
OK, ich probiere und berichte
Danke! 73
Danke für den Tipp, aber das Hauptproblem ist die 1,968GHz LO welche am Ausgang rauskommt, sogar OHNE Signal am Eingang. Und zwar nur ca. 25db schwächer als das Hauptsignal.
Im Schaltplan sehe ich keine Änderungen zwischen den Versionen die eine Reduzierung des LO Pegels am Ausgang bewirken könnten.
Ich vermute das könnte an einer Änderung an den Parametern des RFFC2072 ICs liegen.
Gibt es die Möglichkeit die Parameter von einem "neuen" BU500 ohne dieses LO Problem 1:1 auf einen "alten" zu kopieren?
Ich werde trotzdem probieren einen Kondensator dort einzulöten, evtl. hilf das ja wirklich auch gegen das LO Problem
73s DB8TF
Hi Darko, i modified my "old" BU500, removed the weak output bandpass an added a attenuator on the input like on the 100mWpin version.
Works well now but i have still one question:
What was changed on the "new" version to get the LO attenuation higher?
73s DB8TF
Install a "virtual audio cable" and use its output as your input.
https://www.vb-audio.com/Cable/
73s DB8TF
Wrong polarization?
Just used the free time and nice weather to test if i can reach the QRPP receiver in PY with very small equipment.
Using my old BU500 (@ 450mW) and a 4-turn helical roughly aimed to QO100 gives -13/-11dB SNR... much to strong!
Then i used a old WiFi omnidirectional antenna > -16dB …. still to strong to participate…
Next time i try with a dummyload
BTW: no problem with the TX frequency drift of the BU500 in direct sunlight
73s DB8TF
thank you
Maybe some AF filter settings are different between RX/MMSSTV.
Ok, but i can tell you that MMSSTV could not decode the PY Station.
Found the saved Picture.
Was mode SC2-120 and MMSTV (at least here) won't decode it.
73s
Hello OMs!
As the forum search returned no hits for "RX-SSTV" i post a link to this SSTV decoder here.
It has some more SSTV modes than the "old" MMSSTV even that it uses parts of the original MMSSTV.
I encountered some PY stations a few days ago on SSTV not decodable with MMSSTV.
With RX-SSTV the Images could be received.
Link: http://users.belgacom.net/hamradio/rxsstv.htm
73s DB8TF
Display MoreHallo Florian
Ah OK. I don't saw the relation between "Dirk Fischer Elektronik" and "DF Elektronik". I bought it last year in Friedrichshafen. I know of an HB9-OM who also bought his there.
Edit: An DL-OM with which I had a QSO also has one. Dirk Fischer selled 3 pieces of his up-converter in minimum.
I see, you closed your survey.
I have enabled the option to change your choice if you want.
The survey is running 7 days and then we see what the final result looks like.
73s DB8TF