Speaker Prgoress.....Kind Of.....

Good gravy, it's Friday again?

Been pretty busy with several projects running concurrently. I'm still working on the Heathkit receiver, but I back-burnered it for a while to build these speaker "kits".

And finishing these up can now proceed apace as I *FINALLY* have all the various nuts, bolts, screws, and other misc stuff to wind up this project.

Selling these things as "kits" is dangerously close to false advertising. They're NOT "kits".

They're not even "SEMI kits".

These are a collection of parts packed in a box from which a functioning speaker can (hopefully) be assembled after you the builder  round up the rest of what should have been included in the box.

Le Sigh.....


Anyway.....


I power sanded the now glued-together-and-cured boxes to get them all squared up, and to make sure the front face was flat. There's going to be a bead of glue between the boxes and the front panel, and while that should be enough to seal the front panel, I still wanted them nice and square.

This is about as good as I can get them with my Flint Knives and Stone Axes.

And then after I sanded them, I blew them out, wiped them down, and dragged them back into the basement to put the foam inside. The box on the left used one piece of foam for the back panel where the speaker terminal plate mounts, while the box on the right used several pieces to cover that area. The left one has a round hole cut in the foam to clear the speaker terminals, while the right one didn't need to be cut because I pieced the foam together from some scraps while waiting for another sheet of foam to get here from Parts Express.

Then I built up the two cross-over networks on some perfboard I bought. I spaced the power resistors about 1/4" off the board with some little ceramic spacers I have for that purpose. The two resistors form a 12dB "L-Pad" (attenuator) for the tweeter, and while I doubt I'll ever run enough audio power into these to heat up the resistors, I always mount them spaced off the board because "Good Construction Practices".  I've seen some boards that were blackened and delaminated because of the heat the resistors gave off, but those were usually power supply type applications.

Here's a better shot of one of the networks. The 'white stuff' you see along the coils and capacitors is some "DAP" caulking compound used as "Staking Compound" to hold the parts securely to the perfboard. This should eliminate the parts vibrating against the board, which can make strange "buzzing" sounds emanate from the finished speaker. It also helps reduce any mechanical stress the soldered connections are subject to, helping to keep the soldered connections from fracturing. I used the DAP caulk because I couldn't find my supply of NON corrosive RTV silicone rubber. It's important NOT to use regular "Household Grade" RTV on something like this, as the regular "Bathtub Caulk" stuff releases Acetic Acid as it cures (the vinegar smell), and acid vapors are not something you want floating around in an electronics assembly.

And I even labeled the leads to the speakers and input.....

And since we're expecting temps in the high 50's/low 60's this weekend, I might get the first coat of the "Acry-Tech" rolled on.

Crazy Winds and a Yummy Dinner

It's been rather windy here the last two days. I knew it was coming, so I dropped the vertical antenna down, and sure enough, Saturday morning the wind was howling.

We've been seeing sustained 35+MPH with gusts to 60, which is way more than enough to turn my $300 BuddiPole antenna into $10 worth of scrap aluminum and brass, so down it comes.

The temperature's been 40's/50's during the day, and teens at night, so we're roughly normal during the day and a few degrees cooler at night.

But we're woefully light on rain and snow this year. Hopefully we'll make some of it up during the Spring snows and rains.

And for dinner tonight we went to one of my favorite little places in Old Town, the HuHot Mongolian Grill. It's 90%+ what my favorite Mongolian Grill type place is, and it's close, so win-win!

Had my typical mostly beef bowl with some "MeSo Garlic" sauce, a couple of spoons of "Burn Your Village Down" mild-hot sauce, and a spoon of "Kung Pow.....YOW!" sauce to spice it up a bit. HINT: Make sure ALL you get in the ladle is the red tinted oil. DO NOT get any of the little seeds in it or you might regret it!

Lots of water chestnuts, bean sprouts, some carrot, and green beans rounded it out, and made for quite a savory meal.

And it's 2130 here, and the wind is still howling.....

Battleship Iowa to be the Home of the National Museum of the Surface Navy

I'd heard this was in the works, but didn't want to say anything until it was official.

More information can be found at:
 
Surfacenavymuseum.org

From the press release:

We're Transitioning to the National Museum of the Surface Navy!

Battleship IOWA Museum announces expansion of its services and exhibition space to include the National Museum of the Surface Navy (NMSN). The mission of the museum is to raise awareness of the United States Navy Surface Fleet’s important role in international relations, free trade, humanitarian assistance and technological innovation.

The NMSN will be located on the second deck of the legendary warship, also known as the “Battleship of the Presidents” signaling the four commanders-in-chief who have graced her teak decks. Fundraising for the $19 million expansion is underway and envisioned as a community-based and future-oriented facility to be harbored at the Port of Los Angeles, the nation’s busiest. The mission of the museum is to raise awareness of the United States Navy Surface Fleet’s important role in international relations, free trade, humanitarian assistance and technological innovation.

The work will be done in three phases and will be completed in 2030. The 15,000 square foot refurbishment will begin with a proposed move to the anchor location at the newly redeveloped San Pedro Public Market on the LA Waterfront. A veterans’ park and large outdoor amphitheater will be built adjacent to the ship for exhibitions, military services and days of remembrance such as Veterans’ Day and Memorial Day. Nearly 15,000 square feet of exhibit space will be added by removing unneeded berths. An additional 20,000 square feet of below deck exhibit is planned as well as a building ashore that will provide an additional 20,000 to 50,000 square feet to showcase on-going and transient exhibits, theater, classrooms and lecture halls. Chairman of the Board, Rear Admiral Mike Shatynski US Navy (Ret) states, “Battleship IOWA Museum’s location at ‘America’s Port’ serves as a daily reminder of the Surface Navy’s role in the protection of the world’s sea lanes since 90% of world trade and 99% of internet traffic is by sea.”

“Battleship IOWA serves as a great reminder of the extraordinary things man can do for man.” says Battleship IOWA Museum’s President & CEO, Jonathan Williams. “I passionately believe in providing a conduit between the Navy and the civilian communities to build public awareness throughout the world.” Additional program and exhibit plans include highlighting the past and future roles of the Surface Navy, Next Generation Science Standards educational programming, and a Veterans Center to provide services and curricula which lead to a successful transition for military service members.


UPDATE****** There's a nice video here explaining it better.

SpaceX Scaling Down In California......?

Interesting article over at the California Political Review.  Seems Mr. Musk will be building the Rocket Formerly Known As "BFR" at his existing site in Texas.

He canceled a lease with the Port of Los Angeles for a 19 acre parcel where he was going to build the rocket. And they've also laid off 10% of their workforce "to become a leaner company".

The article is loaded with links to other sources, and is pretty interesting.

Go RTWT

Bits 'O This and That

Got the little speaker boxes glued together. Now I have to sand them, coat them with some 'bed liner' type stuff, put the foam in them, wire up the crossovers, yadda, yadda, yadda....

Probably would have been a whole lot easier to just get ready-made speakers, but I've never built a speaker before and thought it might be interesting.


And I bought new magnifying lamp for the workbench. This one has a bigger lens, 4 brightness levels, and 4 presets for color temperature selection. The other lamp is now clamped on the bench where the speaker and Commodore projects are currently residing. I'm trying to find a replacement fluorescent tube for it, as it's a good little lamp, but the tube is fading.

 

And I finally got around to gluing the busted coil back together for the Multiplex Board on the  Heathkit AR-15. Took a bit to figure out how to "fixture" it together so it would be stable while the glue dried. I ran a length of #18 tinned copper "Bus Wire" through the form and the tuning slug, and then clamped it in one of my little thingamabob holders. Worked like a champ, and after the glue on the one side had dried I can flip it 180* and glue the other side. Then I have to tin and solder the #40 wire from the winding back on to the correct lug. I'm just lucky this was a coil, and not a transformer with multiple windings, like an I.F. Transformer.

Speaker "Kits" Arrived Today

And calling these things "kits" is being overly generous.

Calling them "semi-kits" would be more accurate, but even that's a stretch.



Nope, this is a collection of parts, packed in a box, and shipped out.

And why, pray tell, are power tools and hole saws on the bench with right out-of-the-box speaker "kits"?

 
Why because they didn't give you any way to connect the assembled speaker to the stereo! I suppose I could have drilled a small hole, and run a few feet of wire out, but what then? No, you need an Interface Connector to handle that function. Since the output connectors on most real stereos are some form of a "5-Way" Binding Post that accepts banana plugs, having matching connectors on the speaker is the way to go. So, drill a 2" hole with the hole saw, and mount these nice little "5-Way" Binding Posts plates in the new holes.

Screws not included, of course.

After drilling, just press-fit in the hole.

 

Might as well do both at once while I have the tools out.....

 
The pre-made hole in the back panel of the speaker is for the "Tuned Port", a deliberately sized "air leak" in the box that lowers it's Resonant Frequency, which increases the lower (Bass) frequencies the speaker can reproduce.

 

Mocking them up sans glue.....

 
And here they are with the side panels and stiffening baffle glued in and lightly clamped.

I'm not a cabinet maker, and never pretended to be one, so I have to say these 3/4" thick, MDF, "CNC Cut" pieces fit together beautifully! After a 24-hour glue curing time, I'll fit the two remaining pieces, and glue them in. The front doesn't get glued on until the very last, and I'm thinking of maybe screwing it on with a thin gasket in there.

The enclosures get lined with acoustic foam to subdue high frequencies inside the box (makes the treble less "harsh"), and the cross-over assemblies have to be built.

No circuit board provided, of course.

Then the speakers get screwed into the front panel with the screws that were not included with the "kit", and the two speakers get wired to the cross-over network, and the input to the cross-over network gets wired to the nifty little Interface Connector I installed on the back, guess who supplies the wire, and the front gets mounted (somehow), and they should be ready to play.

Rather than leave these naked MDF, I'm going to coat them with something like bed liner that Parts Express sells. It's water-based, so the odor won't drive you out while it's curing, and it's extremely durable. I'll sand them out before I do it, and come up with some way to make the front removable.

Oh, and I've had to order about $50 in additional parts (so far) to build my "kit" speakers.

Vintage (Ancient?) Home Computing

Had to clear off the "workbench" on the other side of the room I use for my downstairs workshop so I can build the speaker kits when they get here.

After the bench was cleaned off, it looked a bit too empty, and I had these boxes stacked under it, and I really wanted to see if this stuff still worked, and.........

An hour later (had to find all the cables) I had my Commodore 128 set up and running "VR85", a satellite tracking program.

Three of the four disk drives I have appear to have developed problems. Two of them act like the AC power socket is intermittent, and one of them has a problem with release lever not working. Sigh......more stuff to fix....

Anyway, now that the C=128 itself appears to work OK, and the monitor is clear and sharp, the plans for this computer include getting it on Packet Radio with my "A&A Engineering" DigiCom64 modem (right) and DigiCom64 program cartridge (left).

This is the gear I used when I used to contact the Hams on the MIR Space Station. I had just gotten back into Amateur Radio a year before, and had moved in to a really cool bachelor apartment in a large two-story commercial building. The landlady let me put up antennas, and I was off and running! Didn't have much disposable income, so I had to get pretty creative in assembling a station. I had an old, beat-up Alinco DR-590 that I pieced together from several junkers, and an Antenna Specialists 2 Meter vertical that somebody gave me that needed to be disassembled, cleaned, and reassembled to get all the corrosion off it. I used the radio on simplex and repeaters for voice work, and by unplugging the microphone, and plugging in some adapter cables to connect it to the modem, I used the same radio with the Commodore on Packet.

This is a "spare" modem in the picture as I can't locate my original one, but the cartridge is the same one I used on packet back in the middle 1990's, before cheap Internet came along and pretty much killed off Amateur Packet Radio.

Since the Commodore can't multitask (i.e. run more than one program at a time) I had to run the tracking program to see what satellites would be visible, and when, and print out the pass predictions, then load the DigiCom64 Packet Radio software and make ready the radio for digital operation. It worked a treat, and what looks ancient, archaic, and obsolete today was actually not that many years out of the "state-of-the-art" category at the time.

And it was CHEAP! I got the C=128, two disk drives, and the monitor for $40 from a friend. The tracking program was $15, the packet modem was $65, the radio and antenna were FREE, and I had about another $75 in cable (most of that cost was new feedline for the antenna), connectors, and misc stuff.

For less than $200 I had a complete "2 Meter/440" station that I could use on voice, packet, and track satellites with. Pretty sweet at the time.

And 'ya just gotta love those 8-bit graphics!

CNN Kills Pro-Wall Story From San Diego

This came in the morning email from a friend.

CNN Defends Decision to Spike Local Media Pro-Border Wall Interview: 'This Is a Non-Story'

 

And they wonder why their ratings are in the toilet.....

Speaker Choices.....

With the rebuild of the Heathkit proceeding apace, I'll need to get some real speakers for it. I have some "P.A. Type" speakers (carpet covered, 8" woofer and a dome tweeter) that I could use, and some Radio Shack/Realistic/RCA "Optimus" mini-bookshelf speakers, but the P.A. speakers aren't really for music (no top or bottom end; all tailored for voice), and I could easily turn the little Optimus speakers into smoking ruins with the Heathkit. Since the amplifier section of this receiver is known for being less than 100% stable with 4 Ohm speakers of current design, and 16 Ohm speakers aren't very common, that leaves me with 8 Ohms as the 'load impedance of choice'.

The amp section is rated at 75 Watts-per-channel with the "Institute for High Fidelity measurement method", and that translates to about 55 Watts RMS, which is much closer to "Real World" than the IHF method. Some of the methods used to measure the power output of an audio amplifier are quite....uh....."creative", and were devised to inflate the RMS power measurement for advertising purposes. I used to chuckle when I read some of the results, as they were grossly higher than what the thing would actually put out.

So, I need some 8-Ohm speakers, rated for around 100 Watts. You can easily spend $2k per speaker, something I'd never do unless that rich Uncle I don't know about kicks and leaves me a few semis full of cash.

So after receiving a $25 discount code from Parts Express, I pulled the trigger and ordered two "Hitmaker MT" speaker kits, along with some bits (like binding posts to connect them!) needed to finish the kits.

They should be here in a week or so, and I'll report on them when they get here.

And since it's going to be raining/sleeting/snowing on Friday, I put the BuddiPole vertical back up. The winds have died down for the present, so it's safe to get it back up in the air.

Heathkit AR-15 Progress

Been chugging along on the Capacitor Replacement Train here for the last week, and as of tonight, all fifty-four of the printed circuit board mounted electrolytic capacitors have been replaced.

These boards are (from left-to-right) the Multiplex Board, which handles the special process of reconstructing separate left and right channels out of  what's broadcast, then two identical Power Amplifier Driver Boards, which take the selected audio stream and amplify it enough to drive the four power transistors mounted on the heat sinks. Above those two boards is the Power Supply Board. This board provides mounting space for the main power rectifiers, as well as the circuitry for several other regulated supplies.

The circuit board with all the control shafts jutting into free space at the top of the picture is the Control/Preamplifier Board, which selects the input you want (Phono, Tuner, Tape, Aux), processes the audio for Bass, Treble, Balance, and Volume, and then sends it to the Power Amplifier Driver Boards.

In the picture below you can see how all the pots (potentiometer) the shafts are connected to are soldered onto the Control/Preamplifier Board. I wound up having to take this thing a lot further apart than I wanted to, but it was the only way to get enough access to the Control/Preamplifier Board. At least it gives me a chance to clean both sides of the dial glass!

This is the "top" of the component side of that board, as seen looking towards where the front panel normally is, with the old caps in place.

And this is the "bottom" of the component side with the new caps installed.

Besides replacing the caps, I cleaned all seventeen controls, the Input Select rotary switch, three slide switches, and seven rocker switches. Some of the controls I could only get at from the top, and the rest I could only get from the bottom, so cleaning them was a multi-day affair, depending on what side of the chassis I was working on.

On the Tuner Board, I replaced all the electrolytic caps, and cleaned and lubed the bearings in the tuning capacitors. The two rectangular grey boxes are 10.7MHz crystal filters. These give this receiver razor-sharp tuning, even in crowded Metro areas with 50kW stations all over the place.

And I disassembled the heatsinks, cleaned them to get all the old silicone grease off, and them reassembled them with new thermal pads instead of using mica washers and grease. That's a new 3-wire grounded AC cord temporarily strapped to the chassis.

After doing these heinous things to this old war horse of a receiver, I rounded up the usual suspects to interrogate them.

As expected, they knew nothing....Off to the landfill with them! I've seen used parts like this for sale on eBay. Seems people are looking to reproduce "Vintage Tone", and as all the Audiofools know, you need Vintage Parts to get Vintage Tone! Seriously.......

Now I'm In Work coming up with some mounting bracket to use with the replacement power supply filter. The OEM cap was 8,000uF @ 90VDC, and even though the new one is 10,000uF @ 100VDC, it's considerably small in diameter; 2" vs 3".

So even though she's a stripped-down hulk right now, work is progressing, and I'm looking forward to doing the alignment on it with my new test gear.

Have fun, be safe, and Carry On!

Windy!

Been running right around 35~40MPH sustained, with (predicted) gusts to 65~70MPH.

Be careful out there, especially if you're out on the highways.