FCC regulations

The metal cabinet on the Kaypro II reduces the radiated electrical energy to a low level. The radiated interference on the weak, low-frequency television stations (channels 2 and 5) in my area was negligible.

The unit I tested did, however, have some conductive radiation through the power lines. My wireless intercom became noisy when the unit was turned on and really set up a racket when i used the disk drives. A filter in the line cord cured most of the problem. I checked with Nonlinear Systems, which confirmed that my evaluation unit did not have an internal line-filter installed. The company was aware that such a filter was needed and planned to install one on future production machines.

(Infoworld, October 18, 1982)

Early Machine Issues (Not FCC compliant)

Some rural readers have noted that they can't run their Kaypros and their TVs at the same time. So, in recognition of marital bliss week-and to avoid putting old Kaypros out to pasture prematurely-I have a few suggestions.

The oldest (and noisiest) Kaypros have an AC cord that is permanently connected the back panel (not a plug and socket). These units don't have an AC line filter (the AC wires go directly to the on/off switch).

If you have one of these units, the first thing you need to do is purchase an AC line filter. You can get one that mounts on the inside of the cabinet, then you connect very short leads from the power cord to the filter. Or, even better, you can purchase a new cord and filter combination (the filter has a power socket built in).

Now, check the inside edge of your cabinet lid. There should be rectangles of shiny bare aluminum which match up with shiny bare rectangles on the main cabinet (they line up with the screw holes). These rectangles provide electrical contact between the cover and the main cabinet. If you don't have the rectangles, get a good file and make some shiny spots around the screw holes.

These two modifications should cure most of the problem. (You remembered to replace the lid, right?) If you are still having problems then you need to check out the radiation from the keyboard and printer cables.

Take an AM/PM pocket radio and place it near the Kaypro. Tune around on both bands noting any strong signals (might be raspy). Any signals generated by the Kaypro will disappear when you turn the power off.

Move the radio around the Kaypro and see where the signals are the loudest. If your cover is doing its job, the cabinet will be quiet and the signals will be loudest around the keyboard, the keyboard cable, and the printer or modem cable.

You can purchase shielded RS232 and parallel interface cables (or just get shielded multiconductor wire and add your own shielded connectors). Or you can keep the serial and parallel cables disconnected during prime time.

The keyboard is another matter. It's hard to do much with the Kaypro when the keyboard is unplugged and I haven't heard of any shielded phone cables that you could use for the keyboard.

However, you can try bypassing the the keyboard interface. Solder a .01 disc ceramic capacitor (25V or higher rating) between ground and pins 1, 2, and 4 on J3. J3 pin 3 is grounded and you can see the ground plane running to it on top of the circuit board. (Look for J3 stenciled on the top of the circuit board, right above where the keyboard plugs in.) The pin diagram and numbers are stenciled right behind the pins themselves.

Gently scrape the green solder mask from the ground plane (large copper area) so you'll have a space to solder the capacitor leads. Keep the capacitor leads very short.

When you get done with all this, you should have the quietest Kaypro on the block. If that isn't quiet enough then to heck with marital bliss.
(Micro Cornucopia, Dec 1983)

A note about Filter Caps

At this point it is worth talking about RFI or Radio Frequency Interference. The switch mode power supplies used in the Kaypro machines and in most modern computers produces a large amount of interference if it is not suppressed with filtering mechanisms.

All of the power supplies used by Kaypro have basic filtering capacitors (caps) installed from the supplier. Some of these are disk caps and some are film caps. The disk caps are not as good or safe as the film caps. The film caps from this era are usually made by the "RIFA" company. These caps when they are placed across the positive and negative lines can carry 120 or 240 volts through them. They were designed to last about 20 years. The thought was that in 20 years no one would want to use the computer anymore. When they age the outer shell tends to crack allowing the electrolyte inside to go from a liquid to a gas and escape from the capacitor.

This causes the famous "blue smoke" of the machine to be released when the RIFA cap blows itself apart. While removal of the broken cap will allow the machine to run again it can be problematic and reduce the signals/bandwidth of TV, Radio, wireless devices, and Wifi.

They can be replaced with brand new RIFA caps or hard outer plastic filter caps of the type removed (X2 or Y2) except as noted on my Power Supplies webpage. Both should be replaced in another 20 years.

Mr Carlson's Lab did a very good video showing an example of needing filter capacitors on switch mode power supplies like the ones used in the Kaypro machines. You can find it here.

Case mounted RFI filters

The metal case of the Kaypro works great at keeping the RFI signals from coming out but there is one key weak point. The power cord coming out acts like an antenna. To combat this an RFI plug is used. It has additional filter caps built in which minimizes both incoming and outgoing RFI. The first two versions of the Kaypro II did not have a filter plug.

	The cord comes directly through the case. No plug filter.
	The cord comes through a plate in an opening designed for a filter plug but there is no filter plug.
	Finally we have a filter plug.

If you still have interference with other devices after replacing the Filter Caps on the power supply the filter plug is the next item to replace.

FCC Compliance

In America the FCC requires compliance of equipment used in some Commercial and all Residential areas. FCC compliance certification is the responsibility of the manufacturer. The FCC makes the manufacture perform the tests and submits the results to the FCC.

The initial Kaypro II did not have FCC compliance. In the September NewsGram to dealers Kaypro states, "Pursuant to FCC rules each computer must carry the enclosed sticker. Please attach them to any computer shipped to you before September."

I believe the sticker that they are referring to is this one.

I would suspect that in September they began putting them on in the factory.

The FCC ID registry shows that R Johnson is the contact at Kaypro for all of the FCC IDs. It is likely that this is Roland Johnson.

FCC IDs Issued to Kaypro

ID	Product	Date Issued
CUL7XL81-003	Kaypro II (81-003)	Dec 13, 1983
CUL7XL81-004	Kaypro 4 (81-004)	Jan 4, 1984
CUL7XL81-015	K4 (81-015)	June 28, 1984
CUL7XLKP2	All K2, K2X, New 2, and Kaypro 1	July 18, 1984
CUL7XLROBIE	Robie	July 18, 1984
CUL7XLKP4	K4?	Aug 1, 1984
CUL7XLK286	286?	July 2, 1985
CUL7XLK10	Kaypro 10	July 7, 1985
CUL7XLK16	Kaypro 16	Jan 13, 1986
CUL7XLKMD	?	March 19, 1986
CUL7XL2562	?	June 23, 1986
CUL7XL3298	?	June 23, 1986
CUL7XL3805	?	June 23, 1986
CUL7XL3918	?	June 23, 1986
CUL7XL4310	?	June 23, 1986
CUL7XL4344	?	June 23, 1986
CUL7XL4690	?	June 23, 1986
CUL7XL4703	?	June 23, 1986
CUL7XLK386	386?	Sep 2, 1987
CUL7XLK2000PLUS	Kaypro_2000+	Sep 25, 1987
CUL7XLEXT5.25	External 5 1/4 Drive?	Oct 8, 1987
CUL7XL286	286?	Oct 19, 1987
CUL7XLK286I	286i?	Dec 18, 1987
CUL7XLKP1A	Kaypro Micro 1	Apr 18, 1988
CUL7XL286-16	286 (81-068)	Jul 25, 1988
CUL7XL286I-16	286i 16?	Jul 26, 1988
CUL7XLKC2	KC2	Oct 24, 1989
CUL7XLKC1	Kaypro KC1	Dec 13, 1989
CUL7XLKPHF	?	Dec 13, 1989

They would get FCC compliance and the II, 2, 2X, and 4 would bear these stickers.

I have not seen an FCC sticker on a Kaypro 10 or 2000.

I have not been able to find on the FCC website the ID CUL7XLPC10. These appear on some Kaypro PCs.