John,
The most common cause of 20 meter failure on the K1 is the 22 MHz
crystal on the filter board is not active enough to provide a sufficient
LO for the Pre-Mixer.
It is possible that the 15 meter crystal (29 MHz) is not sufficiently
active too, but I don't have enough information to draw a firm conclusion.
To confirm that the crystal(s) are the problem, put the RF Probe on the
filter board P1 pin 4. If the RF voltage is less than 70 mV, there is
not enough energy to adequately drive the mixer.
If you do have sufficient RF at P1 pin 4, then you attention should
focus on the tuning of the Pre-Mixer bandpass filter for 15 and 20
meters. Remember that you must tune 15 meters before tuning 20 meters.
73,
Don W3FPR
On 10/24/2013 10:35 PM, John Reed, W8DE wrote:
My K1-4 was working well when I first built it. Now I'm having some problems
on 20m and maybe also 15m. Here is what it is doing:
40m and 30m: receives well and transmits 7 watts as calculated with voltage
measurements on the DL1 dummy load.
20m : no reception and no signal heard from the XG2 signal generator; no
voltage measurable on the DL1 dummy load indicating no power out
15m: no reception (I don't have a signal generator to test on 15m); no
voltage measurable on output, but I can receive a signal from the K1 on my
general coverage receiver.
What I've done so far:
1. checked that the filter board crystals are oscillating by putting my
general coverage receiver antenna near the crystals and tuned to the crystal
frequency
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