Russ Hines <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Hi Lars:
Thanks for the info, I'll check that out. I've never had the occasion
to measure the level at EXT ANT while in transmit. I'll guess the
reason you get 0dBm is because of leakage through the series UM9401 PIN
diodes. In transmit, they're biased off, but there's I think 1/2 volt
or something on the anodes. The transverters I'm currently looking at
require anywhere from 100mW (20dBm) to a few watts of IF input, so I
would also need to build another amp to boost this.
Let me add a note for others. The RCA connectors for EXT ANT and EXT RX
may be jumpered inside the cabinet on your TR7 (a later modification, I
think, added a gas arrestor for static protection to the EXT RX
connector). The jumper must be removed for the external switching
scheme to work. Do not remove the gas arrestor, it goes from the center
pin of EXT RX to chassis ground.
Thanks again, Lars.
73,
Russ
WB8ZCC
Lars E. Pettersson wrote:
On 06/05/2005 09:26 PM, Dick Harms PA2DW wrote:
The only disadvantage is that the TR7 does not have a
low level RF output on the TX side that disables the PA.
It does!
You have 0dBm of power available at "EXT ANT". If you ground pin 8 on
the accessory plug, you disable the PA.
<snip>
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Here is a version using only the Drake TR7
<snip>
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