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June 2009 Archives


28 June 2009

The Z100 CW tuning aid kit is no longer available. The last kit has been sold and there will not be another run.


26 June 2009

I've added a sample of the optional performance report to the Z10040 Norton Amplifier page, along with comments from an amplifier builder.


22 June 2009

I've been remiss in not adding to this page. I'm still working on the antenna multicoupler, and have decided to change the design considerably. The result will be a better product.

Every few months, I visit the local Michaels arts and crafts store to see what's new that might be usable in my shop. I find the beadwork section to be the most fruitful for odds and ends usable in the shop and today was no exception.

In addition to picking up a couple of inexpensive plastic storage boxes (made by Darice, about 10 inches x 8 inches, with 17 compartments) I found another Darice storage box perfect for attenuators.

I had kept my attenuators in a small wooden box to which I added partitions and felt padding (all from Michaels) but have more attenuators than fit into the box. While wandering through the beadwork section today, I found a small storage box, also made by Darice, perfect for attenuator storage.

As the photos below show, it's nearly a perfect fit for N attenuators and two BNC attenuators fit into each compartment. Since the lid attaches with a real mechanical hinge, not a plastic flap, it should hold up reasonably well. It stacks flat with similar boxes.

These boxes come in blue and red, with the red version having a slightly different partition design--one full width partition, and a corresponding reduction in the length of the five compartments. I think the red version would be a tight fit for attenuators, but I didn't measure it.

Both the blue and red boxes are $2.00 each.

14 June 2009

I've updated the Z10040B Norton amplifier manual to reflect changes to the design and construction instructions to improve stability. The changes apply only to the "B" version amplifier and existing purchasers of "B" equipment have been informed of the changes. The Norton amplifier page is here, and the manual may be viewed by clicking here. (It's a 4 MB PDF file.)

I've also received questions about the status of my active antenna kit. It's still in the works, but I plan to first finish the 4-output and 8-output antenna multicoupler / distribution amplifier first. I've bounced back and forth between two alternative designs for the multicoupler, and after making more measurements this weekend, I am closer to deciding which track to follow.

I'm hesitant to provide promised dates, as things always take longer than I think they will, but I hope to get back to the active antenna project in early July. So far, reports on the one active antenna in daily use are very promising.


09 June 2009

I recently purchased an HP 8970A noise figure meter and AIL 7615 noise source and had a chance today to measure the noise figure of the Z10040B Norton Amplifier. I've added a plot of measured noise figure for one Z10040B amplifier and have established the noise figure performance specifiction as 3.5 dB 10-30 MHz, with less than 3 dB being typical. The one "B" amplifier I measured is not much over 2 dB but I'm  reluctant to say all Z10040's will be as good until I have data on more units.

Details at my Norton Amplifier page.

I've also updated the Z10040B Norton Amplifier manual, available by clicking here.

07 June 2009

I've replaced the Z10040A Norton Amplifier kit (and assembled Z10040A) with a revised version, the Z10040B. Details at my Norton Amplifier page.

The main changes to the "B" version are:

  • Balanced or unbalanced input based on connector pins used
  • All resistors are now 1% metal film instead of 5% carbon film
  • Two color magnet wire (red and green) are supplied for the bifilar windings of T1 and T3
  • Small changes to silk screening to improve legibility
  • Improved the pad spacing for shielded inductors L1-L4

The performance specifications  remain unchanged between the A and B versions, save for a new specification, common mode rejection, that applies to balanced input only.

The Z10040B is the same price as the "A" version. "A" kits are no longer available.


04 June 2009

Before the vector network analyzer, dinosaurs ruled the world and real men used bridges or slotted lines for VHF and UHF impedance measurements. Or so it seems.

I've added a new page with a look at how VHF and UHF impedance was measured in the 1950's, using an HP 803A impedance bridge, an HP417A VHF/UHF receiver and an HP608C signal generator. (Thanks to Mike, W4XN, for completing this trio by giving me an HP608C signal generator a couple weeks ago.)

After using the equipment for a few hours today, I'm grateful that the state-of-the-art has moved on. However, the 1950's equipment is still capable of  reasonable accuracy, albeit slow to acquire. The page may be viewed by clicking here.


03 June 2009

In response to a question posted at the Softrock reflector concerning what should  be used to coat a wound toroid inductor to retain the wires in place, I suggested either General Cement's Q-Dope or a home made version. That sparked a dozen or so messages with alternative suggestions and questions.

I've added a page showing how to make your own Q-Dope and comparing the electrical performance of homebrew Q-Dope to commercial Q-Dope and two alternative retaining compounds.

To view the page, click on the following link: Coil Coating Compounds


01 June 2009

I recently purchased a few hundred 10 ohm resistors in both 5% carbon film and 1% metal film style and measured the resistance of 25 parts from each lot. I've added a new graph and associated discussion to my page Carbon Composition Resistors.


01 June 2009

As usual, I've moved the May 2009 updates to an archive page that you may reach by clicking here or via the link table at the top of the page.