5. Other required parts


From Spektrotek

LC31 Link coupler

The link coupler is tuned to your plasma tube and transfers the energy from the PA3 amplifier to the electrodes on the plasma tube. 

For PT tube: LC31S, $ 85
For ST tube, LC31P, $ 85
For BAT tube, LC31TCBA, $ 85

It is required to cool the LC31 coupler with a fan on power levels of 100 watts or more. Which means a fan is recommended for ST plasma tube for more than 75 volts, and required for the BAT tube, regardless of voltage setting. 

EW Tube electrodes

The EW tube electrodes are clamped loosely on the tube, close to each end of the plasma tube. The electrodes are prewired and it is not recommended to extend the wire length. The wire limits how far the LC31 coupler can be placed from the tube electrodes. 

For PT tube: E1W, $ 28
For ST tube, E2W, $ 33
For BAT tube, E4W, $ 38

RG-213 cable

You need a 24 foot/7.35 metre RG-213 cable between the PA3 and the LC31 link coupler. This is minimum length and part of the tuning, do not shorten or substitute for other cable. 

It is recommended that the cable is a little longer, as it can be a bit tricky to remove the insulation on the ends. It will leave you some extra in case you need to do it twice. Longer than 24 foot/7.35 metres is a lot better than too short. 

Also, if you are using plugs and sockets instead of plugging straight into the PA3, youll likely need a little extra as well. See this page

RG-213 cable can be ordered from Spektrotek or from Farnell/Newark (part #: 2425425).

Other parts from Spektrotek

If you’re anything like me, you’ll probably make a mistake somewhere in the process. Having these spare parts means you can get back on track quicker if you make a mistake and a overheated component is the result.

These items can be sourced from Spektrotek, from local supplier or Farnell/Newark.

Spare STW20NK50Z:  $6.25 per unit from Spektrotek (Newark/Farnell)

Spare IRF730 $2.50 per unit from Spektrotek (Newark/Farnell)

From other suppliers

Metal casing

A metal enclosure will provide shielding for the PA3 controller, and protection from electric shock for the operator/user. 

Any metal enclosure will do, but one with plenty room for both the controller and the 19 volt power supply is recommended. Also there will be a lot of cables in there, so too big is better than too small. A cabinet from a discarded desktop computer will do great, which you should find in any junk pile or second hand shop.

Here is one from Cooler Master, price: $49. There are plenty new and used enclosures on eBay

The PA3 controller has a hole in each corner to attach metal spacers for mounting in the enclosure. This connects the PA3 grounding to the enclosure itself and is required. 

You decide if you want to attach all wires directly into the PA3, or if you want to use sockets and plugs. The latter is more sturdy and looks better, but it is not required.

4x Metal spacers

Metal spacers to mount the PA3 to the enclosure. The metal will connect the PA3 grounding to the enclosure, which is required. You’ll need four. Should be available from computer electronics store, Amazon, eBay. DX.com has a 50-pack for 5.99, but beware of long shipping times.

PA3 power supply

The PA3/SPA4 needs 19 volts power to run and to power the fan on the heat sink. Any old laptop adapter at 19 volts should do. 

The small plug (laptop plug) will be cut off, so don’t worry about the size. The wires are either attached to the terminal block on the PA3, or you will solder a new plug on the cable and a corresponding socket on the metal enclosure for easy connection/disconnection.

Price: $5 - $15, available anywhere, here is one from eBay

Note: This power supply is to power the PA3 itself, not the plasma tube. The power supply from step 4 earlier is to power the plasma tube. 

6x Ferrites

Ferrites are clip-on magnets to prevent interference pickup in cables.

You’ll need two for the USB cable for your frequency generator, two for the cable connecting the generator to the PA3 and it does not hurt to put two on the power cable from the large power supply (from step 4) to the PA3 as well. Six in total.

If your USB cable for your frequency generator already has ferrites on it, you should not need to add two more. 

These from Farnell/Newark will do. Farnell/Newark part # 03H8829. They may be found cheap on eBay or dx.com as well.

Cooling fan for LC31 coupler

It is required to use a fan to cool the LC31 coupler on power levels of 100 watts or more. This means a fan is recommended for ST plasma tube for more than 75 volts, and required for the BAT tube, regardless of voltage setting.

This fan from Cooler Master is quiet, cheap and moves a lot of air. 

This fan needs 12 volts power. For example this power supply from eBay. You may want to use floor protector pads or a foam pad to minimize vibration and sound. 

Plasma tube stand

This is maybe the part that needs most contemplation and work on your side. 

The plasma tube must be mounted to something. There is, unfortunately, no stands or holders made to order. Yet. Make one yourself, or modify an IKEA shelf or some other piece of cheap furniture. 

For inspiration, see Spektrotek’s page of customer assembled systems

IKEA TROFAST tube holder

Pros: Easy to assemble and customize. Reasonably cheap. The size and weight means no accidental knocking over the tube. Could have looked worse.

Cons: Large and clunky, takes a lot of space. May look ridiculously oversized when used for a smaller tube than the BAT.

Price: $39

For our BAT tube, I used a TROFAST children’s toy shelf frame from Ikea.  I cut a hole in the two shelves and put the tube between the shelves. A little duct tape on the edge of the shelves (top and bottom, the grey line) makes it tighter and prevents the shelves from moving without applying force.

The link coupler is hanging from the frame with plastic strips, allowing air flow all around. Maybe the coupler and fan should have been mounted below instead. But any heat rising from the tube is blown away by the powerful fan, so I decided to keep it this way. It is approx. 10 cm/3.8 inches distance between the fan and the LC31 coupler. 

In this setup, the wires from the tube electrodes to the LC31 coupler allows approx. 15 centimetres/6 inches distance between tube and LC31 coupler.

The fan is mounted with floor protective padding between the fan and the frame, to minimise vibration and sound. There is hardly any sound from the fan. Fan power is supplied by a leftover 19v laptop adapter with a voltage regulator circuit for 12 volt output. Sockets have been mounted for easy connection/disconnection for both fan power and RG-213 cable.

Wrapped the frame with plastic wrap, left a few holes for air circulation, but not large enough for a nosy cat or clumsy hands. This has proven to work satisfactory. Plexiglass is a more permanent and elegant solution than the wrap, but cling film is fast, cheap and easy to remove if required. 


TROFAST shelves (one pack)

A length of high voltage wire

To connect the power supply output to the PA3 HV input (high voltage input). The wire must be rated to handle the max voltage your tube will be using (my tube can be operated at 180 volts so I used cable rated for 220 volt). 

Length depends on your setup. I used 20 cm of lamp wire from a cable I had spare. Only 2 conductors are required (no grounding connection).

Optional items

Coax connectors for RG-213

If you need to connect and disconnect the RG-213 cable, for example if you are moving the location of the equipment, sockets and connectors for the RG-213 cable are strongly recommended. Another advantage of using a socket is that the shielding of the RG-213 will be connected to the PA3 enclosure, thereby reducing interference. 

NOTE: Operating the PA3/SPA4 with HV input on, without the tube and link coupler connected, will overheat the STW mosfet. If adding plugs and sockets to the RG-213 cable, remember to check that everything is connected in both ends before powering up.

NOTE: You’ll need RF connectors with the right characteristics. Do not substitute with other connectors. 

You’ll need one socket for the PA3 end and one for the plasma tube end. 

Farnell/Newark part# 2396232 (link)

You’ll need two coaxial plugs for RG-213, one for each end of the long cable.

Farnell/Newark part # 1463089 (link)

Consider increasing your order of RG-213 by a foot. This foot is used to connect the PA3 with the socket, shown in the picture below. Depending on your enclosure, the length of the cable used will differ. For mine it was pretty short. The RG-213 is unflexible and hard to work with, so I had a few attempts until I managed to get the cable the right length.

It is better to have a little longer cable between the PA3 and the link coupler, than a little shorter cable.

Coax connector for frequency generator

Coaxial connector for frequency generator input connection. This is NOT for the RG-213 cable, but the signal cable from the frequency generator. You need one. 

Newark/Farnell part # 1169699 (link)

To connect the PA3 to the coax plug (frequency generator input) I used 10 cm of RG-58 cable. You may use RG-213, but it is overkill and the RG-213 is not easy to work with. The cheapest way to get some cable is probably to buy a standard RG-58 coax cable with plugs, and cut off the plugs. 

Cable shoes & connectors for YK-AD2003 power supply

If you are using the YK-AD2003 power supply, cable shoes on the power cable from the power supply to the PA3 will secure the wires better than just fastening them. The screw terminals are approx. 5mm. 

To connect HV input from the power supply to the PA3, I used Bulgin PX0646 Farnell 313970 and Bulgin PX0429, Farnell part# 313993

© Henrik Lorange 2015
Disclaimer: I do not receive any commission, kickbacks or any favors from vendors or sellers of these parts or systems. All information is provided as-is. build this at your own risk. rife tech might not work for your condition. do your own research first. No medical claims are made for this system whatsoever.