Clifton Laboratories 7236 Clifton Road  Clifton VA 20124 tel: (703) 830 0368 fax: (703) 830 0711

E-mail: Jack.Smith@cliftonlaboratories.com
 

I built a one-off 125 KHz low pass filter today, and thought it would be of general interest, so I added a web page describing the filter, its construction and measured  results. You can view the page at 125 KHz LP Filter

I've completed a manual and web page for the Z1500A Common Mode choke. The page is available by clicking here.

The Z1500A common mode choke is not a kit; I do not intend to provide parts. However, the manual is detailed to permit you to build a choke and includes parts sources and approximate pricing.

These chokes are not inexpensive; a pair will cost at least $75 in parts alone. But they are the best chokes I've seen and are usable from 20 KHz to 30 MHz. This requires a multiple core strategy which increases the cost over a simple ham band only common mode choke.

In a discussion with Ron, K8AQC, the subject turned to "soldering iron" and "soldering copper." Ron retired from Michigan Bell Telephone and what we know as a "soldering iron" is a "soldering copper" in Bell System terminology.

In searching Popular Science Magazine on-line, it seems that both "soldering iron" and "soldering copper" were used at least as far back as 1916, but by 1940 or so, "soldering copper" was replaced with "soldering iron."

Of course, modern soldering irons use copper tips (usually iron plated now) and the old direct heat devices were made from a pound or more chunk of solid copper. In that sense, "soldering copper" is a more accurate descriptor. But, from what I can tell, and certainly what I recall from my first exposure to the subject around 1960, soldering iron has replaced "soldering copper" in common use.

Last week, I built three Z10022A high pass filters (passes 1800 KHz and above) for customers. I took advantage of the unusual circumstance of having three filters on hand to see how closely they tracked.

The plots below show the three filters - I was pleasantly surprised to see that the the filters are, for all practical purposes, identical. (Vertical axis is 1 dB/division on both plots.)

I can't promise all filters match this closely, but at least in this instance where I built all three filters in one sitting, the agreement is amazing.
 

The last two months have been very busy, and it's also been income tax preparation time here in the US.

The photograph below shows some—not all—of the paper required for income tax preparation here at Clifton Laboratories. Receipts for every resistor, screw, lockwasher, etc. that goes into my kits. Ditto for every post office shipment and stamp purchased, etc. Records on what parts to into what kits, and details on prototype kits and experimental projects that made it into new kits, or were abandoned or will make it into new kits in 2011.

My wife, who is neither an accountant nor an engineer, organizes the receipts and then computes how many resistors, screws, nuts, etc. go into each kit and how much each cost from these receipts. I help with identifying parts and maintaining spread sheets with cross references and part numbers and component breakdowns for each kit, but she uses paper and pencil for the parts receipt to kit reconciliation. It's about two months work for her. If I had to hire an accountant to do this, I would be out of business. Mind you, I still use a tax accountant to prepare the tax return and depreciation schedules, etc. The combined state and federal tax returns run about an inch thick when completed with all the supporting schedules.