New V-Tech Spectrum Analyzer

V-Tec PS-2 1Ghz Analyzer 

New addition to the bench.  Bought it used for a good price and hope it will be useful for future projects.  Specifically filter design for both transmitters and receivers.

Crystal Test Jig

Crystal Test Jig

Made up a test jig for testing the crystal.  It uses a 1k and 220 ohm resistor at each end and then two caps 10pf and 28pf so you can measure the fs1, fs2, fs3 and fp frequencies of the crystal and put them in the calculator athttp://www.giangrandi.ch/electronics/crystalfilters/xtaltest.html 

This will give the motional parameters of 

Cs  = crystal series capacitance

Ls =   crystal series inductance

Cp =  crystal parallel capacitance 

This values can then be used to empirically design a filter using the AADE filter design program at 

http://www.aade.com/download.htm

Using the simple Sig Gen I am not yet confident of the values enough to build a filter but after three attempts I think that I am seeing enough correlation to begin to at least play with the values in the filter design program.

I have reread the basic few paragraphs in SSDRA (Solid State design for the radio amateur) and EMRFD (Experimental Methods in RF design) and am continuing to learn.  

It will be possible to make a good filter out of the crystals that I have obtained but it may not be close enough to the stock Center Freq of the original Drake filter to work with the other filter.  Using a single carrier oscillator between the two filters to give both LSB and USB the filters need to have center frequencies about 3kHz apart.

Heathkit IG-102 RF Signal Generator

While troubleshooting the TR-4 filters I thought it would be useful to see if this old Signal Generator still worked.  This is one of the pieces from Bill's old heathkit test gear.  I took the cover off to dust it off and check it out.  I sparyed some DeoxITD5 on the pots and switches.  The bandswitch felt 'locked' so I took the knob off and turned it with a wrench and it loosened right up so it was powered up and seemed to work once all the swithes and pots were 'exercised' a bit.

Heathkit IG-102 

Top showing 12AT7 and 6AN6 both original tubes marked Mullard and Heath

Bottom showing variable cap and coils

I looked at the output on my scope and it looked 'OK' to use for a lot of test and repair purposes.  I hooked up the two Drake TR-4 filters and could see the one that worked passed a signal about 3-4 DB down from the input signal when the generator was tuned to the filter frequency and the 'bad' filter would not pass a signal at all.  With the frequency counter and the scope one could plot the response if the filter was terminated 'properly' .