It works! For the past two years, between trips overseas, and one move, I have been slowly eliminating the Radio Frequency Interference caused by the Hybrid engine in my '04 Toyota Prius.

It has been a tremendous journey of reading, investigating, self-education and trial and error construction/assembly of shielding components, filters, ferrites, mobile antennas, mounts, wiring, power supplies and  vehicle construction. I think I went through over 100 yards of 3M 1181 copper foil tape and at least 50 ferrites  in the process!

As of today, my Prius HF and VHF mobile installation is working, operating effectively, and giving great reports on 20 meters. 20 is my favorite band and I was thrilled to hear and work stations throughout North America this evening. What a huge thrill!

I would like to thank Alan, K0BG for all his patience answering my numerous questions and providing guidance, hints and pointers, and to everyone else in this forum who commented at one time or another.

Some "neat" things I discovered while out on a test drive tonight.

1. People stop and stare at the antenna. I struck up a conversation with one stranger who thought it looked cool and at least one person took a photo of my car with the roof mounted HiQ.

2. I can hear all kinds of noise and signals as I drive through the city, and some vehicles are "downright noisy" on HF - I can hear them as they drive by!

3. A drive in the countryside with the HF radio on is 'fun'. The city noise drops away and signals "pop out" at S9.

4. I've learned to watch out for low hanging trees. they make the antenna go "Twang".

5. A new and fascinating dimension of our hobby has enthralled me. I was even thinking about a mobile amp on the way home :-))

There is much that I need to do, including posting some of the numerous photos  of the modifications I undertook, along with write ups and explanations so that others can benefit, and I will do that over the next few months.

73

John
VE3XKD

Hi

I am using a Breedlove mount on the roof of my Toyota Prius. The roof sheet metal is quite thin and a large antenna will cause the metal to buckle. In my case I made a custom aluminum backing plate that fits between the steel ribs that support the roof metal.  This plate should be curved to conform to the curvature of the roof or you may permanently dent the roof when yout tighten up the Breedlove mount if there is a gap between the aluminum backing plate and the roof caused by any curvature in the roof.

Taking the headliner off was easy! A dozen plastic clips and four screws and the roof liner can be easily pulled down.

Hi

Does anyone know the type/ratings of miniature bulb used to indicate band of operation in the Henry 2k Ultra desktop amplifier? This is the limited production small desktop size 2 kw amp that uses a pair of 8873s and has the remoted power supply.The manual doesn't say what the ratings of the band switch bulbs are and they are quite small and fit into a special compartment/space near the front panel.

I have a 2k Ultra that has one burned bulb that I would like to replace.

Cheers

John

Hi

It is best to contact me off-line as there is much to discuss and I have not had time to put any of the numerous photographs, etc, on a web page yet.

A word of warning, it is one tough job! It is a work in progress. You will need a large amount of 3M 1181 copper foil tape and at least 30 ferrite beads of different sizes PLUS I openned the DC-DC inverter and add in extra ferrites and filter capacitors in order to reduce the nose to acceptable levels.

Bonding is a major issue, and there are several critical things requiring bonding.

I am almost ready to make the permanent mount for the antenna, still waiting on a connector from Mouser as  the absolute best place to mount the antenna is on the roof.

For an antenna I am going to mount the Hi Q 3.5 short using a Breedlove mount and an NMO for a Larson VHf-UHF.

Cheers

John

jpavelich 'at' rogers.com

Just wanted to let everyone who drives an '04-'08 Prius  know that after several years of off and on efforts trying to reduce the S9 plus Noise comming form the Prius' Inverter system and engine, I finally have it licked. It is not easy, but it is possible. In fact yesterday I worked Italy on 20 using only 10 watts from my Prius usng a temporarily installed IC 703 with a roof mounted Hustler. More updates and photos will be provided as I finish my radio and antenna installation (Icom 7000 and roof-mounted  3- 1/2 short HiQ) in the next week.

73

John
VE3XKD

Hi

I would be interested in knowing how long a whip the smaller screwdrivers like the Sidekick and the little Tarheeel II can safely support.

Hi

I received a used, and somewhat abused AL-811 for repair. The owner said it 'kept blowing fuses'. I bought it from him as an 'interesting project' to work on. I wanted to test the power transformer in the power supply on the bench before powering it up. Does anyone have any ideas how I could go about safely testing the Power transformer? I assume that unsoldering and checking the primary and secondary windings for resistance and/or open before I apply power is a good idea? How many ohms resistance should a typical Linear amp transformer exhibit?

Does anyone have any thoughts/ideas of other things I might try?

Regards

John

Tim

Reducing the EMI/RFI noise from the Prius involves understanding the sources of noise, and eliminating them one by one.

First I identified the 'power-on' noise - that noise which occurs as a result of powering on the vehicle electronics, primarily the DC-DC converter.

The next noise identified source comes from the firing of the COP ignition system - see Alan's web pages for hints on reducing that. This noise will only be heard when the engine fires, so you don't hear it when the vehicle is powered on, but the engine not running

The next noise source identified comes from the regenerativre braking system. You actually have to be driving around, listening to HF to hear this noise. It appears to be easily solved (according to others - read the archives) by bonding the brake hubs to the chassis.

The final noise source comes from the electric engine.I have not yet worked on that one.

My strategy to reduce the noise was: Identification, then containment (shielding) and finally filtering, where possible. During the identification phase, myself, and others, reported lots of noise on the 12VDC system. This system has it's origins from the DC-DC converter. At first I tried shielding wires and the 12v battery, but there were far too many 12v wires to shield. I bought a used DC-DC converter- to act as a model to take apart, and upon examination, realized that the 12v section needed more effective shielding. I intend to open up the converter in my car, add in some ferrite beads inside the DC-DC converter, as well as add in a few bypass capacitors. This should reduce the noise. Be warned, this is not an easy job! You need to take out the DC-DC converter, drain the coolant in the center unit (the converter has three sections: top, middle and bottom), open it up, add in the filtering, and seal it back up. The seams of each unit require proper bonding. I used a lot of 3m 1181, but discovered that the foul winter weather here in Canada (and undoubtedly the road salt)has actually corroded much of the tape I installed. The next time (sometime this summer) I will put on the tape, then coat it with conductive paint in an effort to keep the copper foil intact.

Cheers

Hi

Here is a link to a homebrew mount idea for the Prius which makes use of the strong mounting bolts that hold the bracket for the rear hatch supporting struts: http://wa8lmf.net/mobile/prius/index.htm

I think that this is likely your best bet for an inexpensve, but strong mobile mount for the tri-band VHF/UHF array.

I have extensively tested the Prius for RFI noise. There should be no noise beyond about 20 Mhz, and with decent bonding/grounding, noise at 14Mhz can be reduced to about S2.

For those interested, a very good site describing the Prius DC-DC inverter technology is here: http://www.techno-fandom.org/~hobbit/cars/ginv/index.html

From my research to date, the DC-DC inverter needs to be opened up and additional shielding/bypassing needs to be done inside the inverter - unfortunately due to time commitments and constant work that takes me overseas to the conflict in Afghanistan, I have not had time to dwelve any further though I am hoping to get to it this summer.

If anyone has attempted to open and shield the DC-DC inverter - or, in particular has tried to bypass the 12VDC system at the Inverter or elsewhere, I would love to hear about it.

73, John, VE3XKD

Hi

The problem with the Prius is that the DC-DC converter generates tremendous RF noise that interferes with mobile HF radio.  I have extensively shielded the converter, all cables going to and from it, bonded it to chassis ground, etc. Rnfortunately the noise radiates along all of the wires, and eventually leaks out. I was hoping that opening up the DC-DC converter and adding in some correct values of bypass capacitors or ferrites would reduce the noise at source sufficiently.

Cheers

John

Hi

The best description I have been able to find, along with partial schematic diagrams, of the DC-DC inverter/converter, is at the following URL:

http://www.osti.gov/bridge/servlets/purl/890029-WIfqPO/890029.PDF

From the pictures, it appears as if some form of bypassing or snap-on ferrites could be added inside the DC-DC converter box.

Cheers

John

Hi

Right now I am trying to tame the charging circuit for the NiMh battery pack in the Prius. The battery lines comming from the DC-DC inverter radiate huge amounts of rfi. I've tried shielding the entire cable system, added ferrites, etc, but nothing cures the noise as well as I'd like. Though I've gone from 10 to 20  over Nine noise levels, the noise is still S6 on 40 and I'd really like to get it down to something like S2 thus I thought to experiment with better bypassing inside the DC-DC inverter. This means buying a spare (used) inverter box and opening it up, trying different bypass techniques and then swapping the box in and out of the vehicle.

73

John

Hi

I can't use coaxial caps as the Hybrid Synergy drive requires to pass large amounts of current and there is no room to install co-axial capacitors. I therefore can only use bypass capacators. I need to install 16 bypass capacitors. If I need to attenuate 3.6 MHz and 7 MHz noise, what value and type of capacitor is recommended?

73

John

VE3XKD

Hi All

Some of you are aware that I have been tackling HF noise issues in a Toyota Prius Hybrid for the last year or so. I am about to obtain a used but serviceable Prius High Voltage DC-DC converter (Toyota calls it a Synergy Drive) and investigate filtering out the tremendous HF noise levels that it radiates. This is the source of the most annoying  noise that radiates from the Prius. If I can filter out the noise using bypass capacators inside the box I might be able to reduce the noise at source, rather than trying to shield it after it exits and radiates throughout the wiring harness of the Prius. Believe me when I say it radiates like mad on ALL wiring harnesses. I have wrapped many of the  wiring harnesses in copper foil, bonded and grounded and still the noise on 40 and 80 is bad.  I have heard from an experienced RFI engineer that I need to bypass each  DC HV line in the converter with  0.1Ufd paralleled by a 0.01Ufd Capacator in order to filter/reduce HF noise spikes carried by the HV DC lines. The noise from the DC-DC converter starts at 2 Mhz, and has a general peak from 3.5 to 13 MHz then drops off. I was wondering if anyone has any experience with such solutions. Are HV (2 KV) disk ceramic capacators suitable? The Converter runs at about 6oo volts. Any and all comments appreciated!

73

John

VE3XKD

I found out that my Windshield wipers were radiating like mad. I opened up the compartment by taking off the wiper blades (three bolts) and then the plastic covering and then bonded everything to ground and shielded the power/control line with 3M 1181 and it reduced my noise level by 2 S Units.

With the Prius there is so much noise that you really need to make a probe and have a portable radio to go probing for noise sources. I have used extensive amounts (over 70 feet) of 3M 1181 tape and at least 20 split beads

So far my efforts have resulted in S5 noise on 20 and S6/S7 on 40/80. Not perfect - but getting better than a stock Prius.

73