Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
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page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Below spec power output issue with VCO &
MMIC Amp Posted: Wed Apr 05, 2006 10:33 am
Joined: Wed Apr 05, 2006 10:32 am
I have built a 2-3GHz VCO and a MMIC based amplifier (both from
Minicircuits) for it separately on FR4 material with SMA connectors.
The VCO operates fine except that the specified output power should
be about 10dBm but I cannot get it to put out more than 0 or 1dBm. I
am using an HP8570 spectrum analyzer to make my measurements. The MMIC
based amplifier which is supposed to have a gain of atleast 10dB and
can put out a maximum power of greater than 13dBm also only increases
the VCO output by 1dBm, so the total output power I get from the VCO
and MMIC amplifier is not more than 3dBm. I have tried everything and
I am following the manufacturers design & datasheets and there doesn't
seem to be anything wrong I am doing. I spoke to Minicircuits and they
said they have not heard of this problem before and advised me to buy
a new VCO and MMIC amplifier unit and try again. Can anyone help shed
some light on this please? I am really stuck here!
Post subject: Posted: Wed
Apr 05, 2006 12:32 pm
Joined: Mon Jun
27, 2005 2:02 pm
To me it sounds like you have a matching problem between the VCO
and the MMIC.
I suggest that you will test each of them separately.
You already mentioned that the VCO doesn't output the required power.
Few questions that comes to my mind:
1. Have you placed
coupling capacitors between the VCO output and the MMIC input?
2. In the final circuit (With the VCO and MMIC cascaded) have you
used a pad between them?
Post subject: Posted: Thu
Apr 06, 2006 11:47 am
Joined: Wed Apr 05,
2006 10:32 am
Thanks for your reply IR. The problem
was with my SPectrum Analyzer or the way I was reading it. I tested
my VCO & Amp with another analyzer I had access to and the circuits
were performing as per spec! Thanks for your help anyway!