[DSP-10] 5V at D1-A1

[kd7ts]

Hi Matt

There are two T/R diode // attenuator chains from U107

1> Qa-Qd --> R137-R140 --> D107,D108 --> D2 --> L25

2> Qe-Qh --> R141-R144 --> D109,D110 --> D1 --> L7

The other diode of each pair (D1 & D2) is driven by +10T to
route the transmit signal.

If we look at the table of outputs VS GAIN, we see that for
100, Qd and Qh are held high, corresponding to the lowest
resistance values. Further inspection of the table shows Qd
held high until we step to 76. At 82, we hold Qe high and
step through Qd-Qa.

At no time are there more or less than 2 outputs held high.

U107 is the current source for the PIN diodes (D1 & D2), and
the different resistor values (R137 - R144) set the
available current.

The voltage table suggests there is no current flowing in
the path to D1.

2> Qe-Qh --> R141-R144 --> D109,D110 --> D1 --> L7

It would likely be L7 not connected on one end or the other,
or maybe it's open.

It still is not clear to me whether or not you are getting
the program to load properly, or at all.

Hope this helps, and let us know what you find.

Mike KD7TS