z series-capacitive coupling-direct connection - reason1st

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Exploring SEC Z Series, Capacitive Coupling & Direct Connection Reason1st - December 29, 2011

1.

Image 1 shows the setup used for the spectrum analyzer screen captures that follow. This setup was an attempt to

replicate Ariochs setup. There is a capacitive coupling via a single ended connection from the signal generator to an

aluminum block positioned next to a standard SEC 18-1 exciter board. The LEDs were brightest when the Al block was

positioned within 1 cm of the board at the end of the L3 coil as pictured. A red test lead connects the L3 coil to a second

Al block and a green test lead connects that Al block to an AV plug driving two white LEDs which are connected together

with a European terminal strip. A second L3 coil is connected to the AV plug input. A black test lead connected to one

of the diodes cathode serves as a counterpoise, so do the two red test leads connected to the other diodes anode.

2.

Image 2 shows the spectrum when the Wavetek 164 SG was turned off with the markers left on from the Image 3 that

follows. The FM radio band can be seen around Marker 7. The SA has high sensitivity at these settings allowing the use

of the thinner more flexible RG-174 coaxial cable which has a higher attenuation but is more easily positioned when

probing around to explore and document the signals. Note that the Al block dimensions are 1.75x1.625x0.75 3.2 oz.


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3.

Image 3 shows a Z Series with SG set to 5vpp at the Marker 1 frequency with all of the original components installed on

the SEC 18-1 board and no connection to the power rails. All SA screens were captured with the 2 white LEDs tuned for

maximum brightness. The SG had to be initially set to 5vpp to light the 2 LEDs, it was later decreased to 3.5vpp when

spectrum energy levels were increased with changes to the setup. Note that this initial Z Series is a multiple of 1.094.

The 50 ohm RG-174 cable was connected to the USB-SA44B and the stripped back stranded center conductor at the

other end was solder tinned. The tip of center conductor was placed on the inside edge of the SEC 18-1 L3 coil load end.

4.

Image 4 shows the spectrum after the transistors emitter was disconnected from the socket, only the transistor base

and collector were left connected. The emitter was disconnected to analyze what affect it would have on the spectrum

and to try to determine the exciters mode of operation, the transistor was later removed for the same reason. Before

disconnecting the emitter the SEC 18-1 D3 LED would only light if the AV plug was disconnected but adjusting the C1

tuning capacitor did not affect the brightness of this LED. Note that after making this one change, the SG frequency had

to be readjusted to obtain maximum brightness from the 2 white LEDs. This shifted the Z Series by 0.547 MHz (1.094/2),

the SG output level was left at 5vpp. Disconnecting the emitter apparently changed the impedance which caused the srf

of the L3 coil to change resulting in a new optimal oscillation frequency.


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5.

Image 5 shows the spectrum after the transistor was removed from the SEC 18-1 exciter board. The SG frequency hadto be adjusted again to obtain maximum brightness from the 2 white LEDs. This shifted the Z Series by 0.547 MHz

(1.094/2) back to the original series, the SG output level was left at 5vpp. Note that the energy levels are higher and the

spectrum is wider.

6.

Image 6 shows the spectrum after the SG output level is changed to 3.5vpp, no other changes were made. This was to

set up a reference output level for comparison to the following SA screen captures which include additional changes to

the original setup at these higher energy levels. Note that in all SA screen captures, Marker 1 is the SG frequency and

only the SA center frequency and span are adjusted for better viewing purposes. The title at the top documents the

setup and the results with a very brief summary.


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7.

Image 7 shows the spectrum with the L3 coil disconnected from the SEC 18-1 exciter board, no other changes were

made and the L3 coil remained mounted to the board with all setup components left in the same position. When the SG

was readjusted for maximum brightness of the 2 white LEDs there was a significant increase in the Z Series frequencies

and they were again a multiple of 0.547 (1.094/2). There was also a significant increase in the spectrum energy levels

and the spectrum was much wider.

8.

Image 8 shows the same spectrum with a wider span setting and some markers reassigned. No changes were made to

the setup, this was only to provide a wider view of the spectrum. Before the L3 coil was disconnected from the SEC 18-1

exciter board the Z Series was not displaying beyond 150 MHz. So in addition to the C1 tuning capacitor not having any

effect on the D3 LED or the spectrum, a spectrum of less than 150 MHz may also be an indication that the SEC exciter

was not operating with this particular setup.


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9.

Image 9 shows the spectrum when the Al block capacitive coupling was removed and the SG was directly connected to

the L3 coil, no other changes were made. This screen capture was to document a reference for comparison to the

following SA screen capture before readjusting the SG frequency. Note that the spectrum energy levels have

significantly dropped and the 2 white LEDs turned off because the srf of the L3 coil had significantly changed due to the

direct connection of the SG to the L3 coil.

10.

Image 10 shows the spectrum after the SG frequency was readjusted to obtain maximum brightness from the 2 white

LEDs with the SG directly connected via a single ended test lead. Note the very significant decrease in the Z Series

frequencies which again fell on a multiple of 1.094. How common are these occurrences? Also note the very significant

reduction of the spectrum bandwidth, with the SG directly connected to the L3 coil the entire Z Series spectrum is now

compressed below the FM radio band. There is no significant change to the energy levels, so why is the spectrum

bandwidth reduced? Is it the lower primary frequency, direct connection, combination of both or other factors?

Prior to this experimentation, the srf of the Coil 4 used with this setup was precisely tuned to 22.015 MHz using the

capacitive coupled SA method and the SEC 18-1 exciter was tested for proper operation with 3 VDC battery power.

z series-capacitive coupling-direct connection - reason1st

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