[Elecraft] XG1: low level output

[Rafael García]

Hi Gary and all,

Just only to share my troubleshooting with the XG1. I think I am the only
one in the world with such a problem. No one has reported a failure after
build their units. (Gary, I had not a spare crystal so I tried this and
worked).

Symptom: Low RF output on both 50 and 1uV position. Weak signal.

Troubleshooting.-

Amazing. After finished my XG1 unit, went quickly to test s-meter response
on my K2. Surprise! Almost barely heard a signal on 7.040MHz in 50uV
position; none on 1uV... Oscillator is producing  a small RF level, not
enough to produce an  indication into s-meter. Checked the BNC M-M adapter,
replaced with a coax cable. Same problem. Got my poor FT-817 (PA kaputt with
no reason but in good receiving condition), and took the same low signal.
Definitevely there is a problem.

Then, I proceeded to check all the resistors junctions with an DMM. They all
were in range as expected per manual. Checked the BNC conector, attenuator
network and back to C4; ok.
Checked battery voltage; ok.
Checked protection circuit, and finally removed (D1, D2); ok.

I sent an email to Gary at Elecraft requesting for help. Several mails
exchanged with him and none of them resolved the problem. As per his
instructions, I checked all voltages at Q1 and, with the help of a scope,
checked the RF signal at Q1's base and emitter leads: DC voltages were right
on but RF signal was almost non existent: it should be very close to 300mV
p-p at Q1 base. I thought I was close to the origin of the problem.
Replaced Q1 with a new one. Problem persist.
I sent a new message to Gary with my decision to leave the project out: such
a simple circuit is  turning me *mad*. I built a K2 a year ago and no
problem to getting in the air with such a complex kit... Gary told me that I
should replace the quartz with any in the range of 3...10MHz, only for test
purpose but too frustrated to continue... Left the circuit apart.

Solution.-
Today, I decided to do one more test: desolder the quartz and resolder again
upside down: problem SOLVED! I got an RF signal at Q1 base as expected.
Read a similar problem somewhere recently and that is.

Conclusion.-
First time ever I see a "polarized crystal". It is sure there will be a good
explanation but I am unable to understand it.

For your interest, I placed the quartz with the label faced esasyly reading
first. Now, the label is faced to the PCB (my English is bad; don't know how
to describe better...)

Regards.

--
Rafael, EA4RJ
Madrid