Ratiometer Antenna Network Analyzer

gevv · Tarih: 15.12.2006, 15:20 Mesaj konusu: **Ratiometer Antenna Network Analyzer**

Antenna Ratiometer or Handheld Network Analyzer
W1GHZ 3/2006

Errata and notes

Errata:
1. U6 was reversed on schematic. Input goes to +12V

2. U5 and U6 are 78L05 regulators.

3. Q1 is a 2N3904 or any generic NPN transistor

4. On the PC board, a few surface-mount pads were covered with green soldermask:
one end of C6 and C7, both ends of C34

5. A few missing items added to part list.

Notes:

1. Small IC packages like U1 and U2 should be soldered with a
temperature-controlled iron (700F) with a fine tip. If you don't
have one, use a Variac or lamp dimmer on a regular iron. One way
to solder the closely-spaced leads is to hit all the ones on one
side with a blob of solder, then remove the blob with solderwick,
which will leave just enough solder on the leads. Be quick,
don't overheat.

2. U6 powers the digital panel meter - the meter specified can be powered from
the same circuit that is being measured
(most cannot, and require a separate, floating battery)

However, the meter has a limited common mode range: both + and - inputs
must be within 2 volts of the negative power connection. U3 pin 7
provides a return that tracks with the zero voltage of the ratiometer, for both
the meter and U6. U6 then provides an output voltage for the meter positive power
connection that is 5 volts higher than the negative power connection, so the meter
is always powered by 5V, but the voltage to system ground moves.

if you were to use a more common digital panel meter, you would need to
power it separately with a battery. then U6 would not be needed. you
could also just use a separate digital multimeter.

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