## hpr2688 :: Explaining the controls on my Amateur HF Radio Part 5

 
The controls covered are

AF / RF gain

(1A) AF, Audio frequency gain control (Volume)
Turns the volume up and down
(1B) RF, Radiofrequency gain control (From the Kenwood manual)
RF GAIN is controlled by changing the AGC (Auto Gain Control) threshold voltage. Adjusting the RF GAIN so that the S-meter reading increases to a point just lower than speech peaks. This also reduces noise during reception. For normal operation, this control should be turned fully clockwise for maximum sensitivity.

CW VBT (From the Kenwood manual)

Carrier Wave Variable Bandwidth Tuning Control
This control is very similar to the SSB Slope tuning controls. However, with the CW VBT control, both sides of the IF passband are narrowed at the same time.

SSB Slope Tune (High pass low pass audio filter)

High pass filter
https://en.wikipedia.org/wiki/High-pass_filter
Low-pass filter
https://en.wikipedia.org/wiki/Low-pass_filter


I mention that the radio uses phase locked loop technologies.
Below is an article in Wikipedia about PLL (Phase locked loop)
https://en.wikipedia.org/wiki/Phase-locked_loop
I mention that the radio doesn’t use valves.
Below is an article in Wikipedia about valves (Vacuum tubes)
https://en.wikipedia.org/wiki/Vacuum_tube
Dry joint
I mention that the radio developed a dry joint
Below is an article in Wikipedia about soldering that covers dry joints
https://en.wikipedia.org/wiki/Soldering#Dry_joint

