Friday, February 1, 2019

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.....


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.


  1. Labeled? You're REALLY doing it right! :-D Nice job!!!

  2. Thanks, it's getting there.

    Some people would say I have entirely too much time on my hands.....

  3. Replies
    1. Thanks, Ed.

      I find if I don't do things like this on a regular basis, my dexterity and brain turn to mush. Kinda like the whole first magazine if I haven't been to the range in a while!

  4. Great progress!

    If I could impose on you a bit for some advice?

    I'm a general class ham, do a bit of electronics repair as a hobby, and I'm building out my radio lab so I can work on older shortwave and ham gear... (no tubes)

    I bought a bunch of test equipment at an auction,and have to sell most to pay for what I keep. The question is what to keep...

    For communication test set, my choices are IFR 1200 Super S, or one of three HP 8920A sets. Selling the IFR 1200 would probably pay for everything else, and then selling two of the HPs would be gravy.

    For spectrum analyzer, I have an Hameg HM5006. The new stuff includes an HP8594E which I can keep, or sell, or sell the Hameg.

    I've also had an older HP Spectrum Analyzer with an 8555A RF section and 8552B opt H17 IF section for a while, but it is big and a LOT more 'manual'.

    Do you have any thoughts on what I should keep and what I should sell? I'd like to end up with one SA, and one comm test set, (including a signal generator in one of the boxes) unless there is a reason to have more...

    (I've got a nice 4 channel O-scope already, a Tektronix 2246)

    I appreciate any advice from you or any other commenter.



    1. If you want real, live, genuine "Lab Quality Gear", it's awfully hard to go wrong with HP.

      I just bought an 8594E right before Christmas, along with an 8657B generator. These were to replace an older Systron-Donner generator which got slightly damaged moving here, and an old Tektronix 492 Spectrum Analyzer.

      The IFR is extraordinarily useful for doing VHF/UHF FM radio work, and I've spent many hours using one. If there's any chance *at all* you'll be doing *any* FM radio or packet radio/APRS, then hang on to it.

      I'd keep the 8594 and sell the Hameg. The Hameg looks to be geared more towards a "Commercial 2-Way Radio" shop, but it does have a tracking generator, making it useful for doing swept alignments on filters, diplexers, and duplexers for repeater work.

      I see the HP 8920 has a signal generator that starts at 30MHz, not much good for HF work.

      I'd have to say keep the IFR and the 8594 and sell the rest.

  5. Thanks Dr Jim, I thought I recognized the 8594. It sounded very familiar. I've got some other gear I picked up from a university lab, sweep and pulse generators, and some filters, too. I've been stacking gear ahead of learning to use it. It worked for me with my radios, so I'm continuing with that strategy.

    For the learning part, I've been watching TRXBench on youtube. He's a german guy who repairs a lot of radios and covers both the troubleshooting and theory. He's got a nice bench. Mr Carlson's Lab is another great channel. He's more into tube stuff and is V E R Y thorough in his process and explanations. VVVEEERRRYYY thorough.

    I appreciate the feedback. The IFR sells for double what the others do so I suspected it was the most desirable. It's also the easiest to sell and would cover my entire purchase price for the lot, so I'll have to consider that too.

    I'll let you know how it goes.

    And thanks again for the advice :-)


    1. Glad to help. You have to keep in mind what frequency ranges you'll need to cover for what you want to do. I had a different Tek spectrum analyzer, but it "only" went to 4GHz, while the one I kept went all the way to 18.5GHz.

      The other one had direct keypad input vs spinning several knobs, and was much easier to use, but as it "only" went to 4GHz, I got blinded by a capability I'll never use and sold the actual better of the two!

  6. I'm PRETTY sure I won't be doing any microwave exploration :-) I mostly just listen to our local big repeater on UHF because it is conferenced to the World Wide Friendship net, and the Alaska Morning Net, and then connected to the winsystem most afternoons. Always something going on there.

    I do some shortwave DX listening, and if the bands seem open, then I'll spin around the ham bands too, just listening. My office/workroom/shack is right next to my 9yo daughter's room, so talking all night isn't really doable. I am a bit limited by my R8 vertical antenna too. Still, I enjoy hearing what's out there.


  7. I'd have to keep the IFR. There's been several times I came *this close* to buying one, but held off because I was able to borrow a 1200 S from a friend.

    They're made to test transmitters and receivers from 100kHz to 1GHz, and as the basis of your test bench would be an excellent place to start.

    You should try digital modes. You can get solid copy on stuff you can't even really hear!

  8. Funny you should say that, I got an old TNC running last year but never got a pc set up or connected it to a radio. I've got a couple in fact, so I can set up an HF rig and a UHF/VHF. Having read thru all the recent QST magazine articles on digital, and the "getting started in digital" book, I'm this close to actually connecting wires.

    I have an FT-847 that was my primary HF rig, that the mic PTT doesn't work. The switch on the radio does though. I got another FT-847 at an estate sale, essentially new in box. SO I finally got the new one set up, and it's my main rig now, with the other one earmarked for digital modes. I understand that using a single radio means switching a bunch of stuff, like mic levels, etc, so this should make it easier. I was able to afford the newer 847 by selling a couple of the other radios from that sale.

    With a couple of small kids, this hobby has to be self financing. Well, all my hobbies have to be. I don't think I have any new gear except the Baofang that started it all, and the FT-60 I upgraded to...

    There are so many facets to the hobby, and I've got so little time, that the few projects I can do tend to get stretched out over a long period of time.

    I found that by having the shortwave and the other radios sitting right next to me all day long, I do turn them on and actually listen about every other day. I know a few guys who don't get their radios on every other month, mainly because they can't leave them set up. At least I can do that much :-)



    1. I probably should have said "Sound Card Modes" rather than "Digital Modes". All the newest bright shiny objects in the "digital" realm use some form of interface to the sound card in a PC, or you use a separate box like a SignaLink or RigBlaster which is basically a USB 'sound card' in a box with some isolation transformers to break any ground loops.

      FT-8 is the current darling, preceded by PSK31, and of course their Great Grand Father, Packet Radio.

      Lots of fun, very versatile, and excellent for weak-signal (or crappy antenna) work.

      I have an FT-847, too, but all I use it for is satellite work. I have an INRAD 2.1kHz crystal filter in the receive path, and a Yaesu/Collins mechanical filter in the transmit path. It's been on 6 Meters a few times, but I don't think I've ever had it on HF.

  9. " I don't think I've ever had it on HF."

    Hah! I don't even have mine connected to any antennas except HF :-) I have a Ringo for VHF waiting for a nice day and a short project list. I've even got a spot picked out and a coax run. To get it completely hooked up, I'd need 3 more antennas than the one I'm running and the house is already looking a bit antenna farm-ish.

    To be fair, I've also got an FT-8900 quad band mobile on my desk, on a dual band UHF/VHF antenna and I use that for local repeater work. The big boy really isn't needed for the upper bands.

    Eventually, I hope to do some airplane and meteor bounce, and satellite. I've got a dual band 'arrow' handheld antenna, and I've watched the youtubes of people completing contacts with their little BaoFengs and that antenna for satellite work.

    Motorized antennas and the big radio are probably out of the question for a long time.

    I've got a decent discone for the scanner, the 1/4 wave dual band for the 8900, and the R8 on the back corner of the house. I've got the Ringo, and a 30cm eggbeater ready to install, when I find time. The eggbeater will feed the SDR dongle. I hope to D/L weather maps and satellite imagery with that, just 'cuz.

    I've got another 144 antenna that I'd like to get up to use with APRS, and a marine whip, for monitoring the port and gulf.

    Like I said, so many projects, so many facets... a lifetime's worth for sure.


    1. Well, I've always had "better" radios for HF use, and I bought it specifically for satellite work. I use an M2 2M7 Yagi on 2M and an M2 420-450-11 on 70cm with a Yaesu G5500 rotor and a Fox Delta ST-2 controller. SatPC32 handles the Doppler correction and sends commands to the ST-2 to move the antennas. Fully automated, and it only took me 10 years to get there!

      I did the "Arrow and an HT" thing a few times, but it wore off pretty quickly. I don't operate the FM satellites because they're just too crowded and you can't (or shouldn't) have more than very brief QSO because there's a zillion others with "An Arrow and an HT" trying to do exactly what you're doing, and the satellite only supports ONE user at a time.

      I don't have *any* "permanent" antennas up here. One of the main problems is getting the cables into the house, and down into the basement where the shack is. The basement is fully finished, so I can't just run cables along the floor joists like I did when I was a kid! I had planned to have a 3" hole cored through the foundation and then run all my cables through a 3" pipe of some sort, but with the tower project off the table, I won't need that big a pipe to bring in a paltry few cables.

      And since the RG-8X cable for my BuddiPole/BuddiStick comes neatly through the back door to the sun room, that's where my K2 is set up, and that's where the "shack" is.

      Our place back in Long Beach had my 33' vertical on the roof of the back patio, a weather station and Comet GP-1 VHF/UHF vertical on the North side of the house, and the South side had an M2 EB-144, Diamond discone, GPS antenna for my HP frequency standard, and a Comet GP-3 VHF/UHF vertical. My Drake TR-270 was in the living room sharing desk space with the wife's PC, and my Kenwood TM-D710 was in the main shack.

  10. I spent the afternoon going thru the stack o gear. The IFR was a mystery. The scope fired up, but the microprocessor didn't- no vfd. I found the uPC card had been inserted poorly, bending one pin, and the power was set to 240v. Once I re-seated the card and switched the psu, it fired right up!

    The SA fired up and works, seems to get good signal. No demod option, so no listening to the radio.

    Of the 3 test sets, one fired right up, seems to be good as the spectrum analyzer shows spectrum... and all the self tests passed. The second was dead, not even fan spin. I'll be looking into that tomorrow. And the third started up, self tested, but the screen has a little burn in, and the SA is deaf. I'll do a reset tomorrow to see if the internal attenuation was set, if not, I'll sell it for parts or repair. The front cover sells for $110, and the front bezel and switches sell for almost double that, so I'll be able to get my money back out of it without trouble. The dead one, well, even the parts should get me money if I can't figure out why it's not coming on. Totally dead units are selling for more than what I paid for it.

    I'm going to take your advice and try to keep the good SA and the IFR 1200. That thing is cool!


    1. Yep, they fall into the "Specialized, But Neater Than Shit" category.

  11. Well, at least you can keep busy through all this cold weather. If I read one more book I'll go blind, but when you are trapped inside, it's read, watch tv, listen to the radio, or do a "project."

    1. Yeah, too cold to do any meaningful work in the garage, so down to "Workshop #2" where I can continue my adventures.


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