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Old April 20th 05, 01:09 PM
Chuck Harris
 
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Reggie wrote:
Chuck, come to find out that the frequency received is 17 khz down from
what the dial reads. Is this an alignment problem. If so do you know
where I can a copy of alignment procedures?


Hi Reggie,

There is a knob on the front panel called "Calibrate/Fine Tune". It is
connected to a 25T pot. It allows you to shift the received frequency
relative to the displayed frequency by something more than 50KHz.

The correct proceedure is to set the KHz dial to zero, and turn the AGC
switch to "CAL", Detector mode to "0", and BFO tune to "0". Then you
adjust "Calibrate/Fine Tune" for a zero beat.

Doing an instrument calibration on a 6217 is a very daunting task. I have
done many, and once was quite good at it. It requires (and by that I really
mean requires): RF signal generator (HP606), AF signal generator (HP200AB),
VTVM (HP410C), frequency counter, noise generator (Marconi TF1106), wave
analyzer (HP302A), or better still a spectrum analyzer, Oscilloscope, DVM,
RF voltmeter (Boonton 91H), Sweep Generator (1-7MHz, with accurate markers),
Logrithmic amplifier (Jerrold 500, 1-7 MHz, or HP7562A).

And further, you need a host of adapter cables for the little microdot(IIRC)
connectors that are everywhere in the unit. Depending on the model you have,
the back panel will either have BNC (preferred), or SMC connectors all over
it.

To make matters worse, all of the tuning slugs have square holes, and they
are extremely fragile. If you don't use the correct tool, they fracture
and freeze inside the coil forms.

On the bright side, there are only a few failures that commonly happen to
6217's, and they don't require calibration. The first is the germanium transistors
in the front end are easy to blow, and impossible to find. NTE used to
have some NOS transistors that worked fairly well, and the second is a 1/4 watt
resistor that protects the VFO burns out when the capacitors get charged up
for the first time after a long period of disuse. The resistor is under one
of the little metal plates on the bottom of the receiver, near the VFO's. The
symptom is noise, but no tuning. And the third problem is the filter caps
in the powersupply. Like all 1960's caps, they are getting leaky by now.

-Chuck