I obviously am not astute in the field of RF circuits as I come from adigital background. I am unable to get advertised output from a RFwideband amp advertised as for the FM broadcast band. The amp isfrom Denmark and uses a single BLW76 transistor. I have isolated thelow power circuit control with no improvement in power. I pulledresister R3 and lifted D1 to isolate the circuit. DC power inputmeasures 23.5 Volts. RF power input measures 7.5 W at 92.5 MHz FM.RF output measures 18W. The output signal is clear and crisp. TheBLW76 never gets very warm beyond room temp. I am using a ME82dummy load combo wattmeter - 52 ohm impedance (military). I onlyhave DVM and Oscope and of course assorted logic probes. Theadjustable caps were adjusted for max output on the wattmeter, inputpair to outpair and repeated until no further gain could be eeked outon the wattmeter. The schematic looks like standard RF Amp stuff,and it matches the hardware. The schematic is located at: black-out marks were on the schematic when I got it)Is the BLW76 faulty? One of the trimmer caps has been replaced on theoutput side. It is a mica compression type not matching the otherround trimmer caps.Thanks in advance for any guidance.Barry

Are all the trimmers midway through their adjustment range? Make sure you don't have any fully meshed or fully unmeshed.What's the DC supply current?

RF Wideband AMP Broken?

Apr 17, 2007 24 Replies

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Phil Allison 19 years ago

** The term "to beg the question" has an important meaning that is now lost because of continual misuse in the media and elsewhere.

Likely not one person in 50 could say with any accuracy what " to beg the question " really means.

........ Phil

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Joel Kolstad 19 years ago

Oh yeah? I'd got an HP 8648A signal generator here which is more than happy to produce FM at base frequencies anywhere between 100kHz and 1GHz. Output is some decent fraction of a watt -- *far* more than enough to violate FCC part

15 regulations with any decent antenna connected to its output.

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Joel Kolstad 19 years ago

Hey, what do you call the GNURadio USRP

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It's just a pair of PCinterfaced DACs and ADCs after all. I guess they were completely off-base in suggesting it could somehow be used as "a radio." You'd better write them a message quick...

Note that there's software for it to make it an oscilloscope, signal generator, FM transmitter, HDTV receiver... surely we ought to ban such devices ASAP!

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Phil Allison 19 years ago

"Joel Kolstad"

** Piss off - you autistic bloody FOOL.

........ Phil

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Joel Kolstad 19 years ago

Telling someone off when you've lost a debate is not considered good form, you know. :-)

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