Thread: FT480R repair
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Old August 9th 07, 07:12 PM posted to uk.radio.amateur,rec.radio.amateur.equipment
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First recorded activity by RadioBanter: Jun 2006
Posts: 147
Default FT480R repair

In article , "Anonymous" wrote:

"You" wrote in message
...
In article , "Anonymous" wrote:
No reason the PLL frequency should change between TX and RX
as I'm only using it on FM simplex.

Just goes to show that YOU really don't understand the technology
that your dealing with...... Maybe a few courses in Modern
Radio Design, would help you understand how the PLL System
works in an FT480R.....


Which bits of it do you say that I don't understand?

Loop stability in control systems, perhaps? Lead/Lag
compensation? Triple loop PLLs to give 10Hz steps but
without the final loop stepping in 10Hz?

What exactly?



It is the part where the PLL Frequency doesn't change because you
at using FM Simplex. There are many reasons for the PLL to change
between Tx and Rx, even with the radio in FM Simplex mode.

1. The receiver may have an IF Frequency of 10.7 Mhz which would
require the PLL to be offset from the Receive Frequncy by the
IF Frequency,
2. The Transmitter exciter may use a different Offset Frequency
than the Receiver IF Frequency, and most Transmitters don't
modulate the Tx Output Frequency directly, but modulate an
IF Frequency that is, either "mixed" to the Tx Frequency, or
"multiplied" to the Tx Frequency.

Just to name a few. Now Sir please, expound your brilliance on why
you made such a Stupid Comment in the Original Post, as sited
above...........