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jazzop

Joined: Tue, Aug 23rd 2016, 22:57 Roles: N/A Moderates: N/A

Latest Topics

Topic Created Posts Views Last Activity
19" Rack-mountable equipment Dec 23rd 2018, 19:36 1 517 on 23/12/18
Should I toss my RG-59 coax? Aug 29th 2017, 06:05 2 840 on 29/8/17
Antennas inside fabric-covered structure? Sep 7th 2016, 22:18 2 878 on 8/9/16
Ham-friendly tips for whole-house rewiring? Sep 2nd 2016, 22:42 4 1,653 on 5/10/16
Equipment type certification vs. conformance? Aug 24th 2016, 06:24 4 1,377 on 6/9/16

Latest Posts

Topic Author Posted On
19" Rack-mountable equipment jazzop on 23/12/18
It would be nice if the QST reviews would mention whether a product is mountable in a standard 19" equipment rack (or if the manufacturer offers optional rack-mounting ears to attach to the sides of the chassis), and if so, how many "U" it requires (e.g., 2U, 3U...).

This begs the question as to why so much ham gear is willy-nilly when it comes to form factor. Coming from broadcast radio and being relatively new to amateur radio, it is frustrating to deal with the seemingly random chassis shapes and sizes of ham gear. Yes, anything can be placed in a rack by putting it on a rack-mountable shelf, but shelving disrupts the ventilation airflow compared to flush-mounted gear that extends across the full 19" opening.
GPS Time input for Laptop KI7LFD on 25/9/17
Sounds like you have made satisfactory progress so far, and the precision you require is not to the level of a true NTP or PTP time server. However, you may find that you have reliability/accuracy issues with the Bluetooth or USB connection, depending on the software you choose to use. In case any other readers of this thread are interested, the simplest and cheapest method I have found for a very accurate GPS time source (i.e., for establishing an NTP server) is to use an older GPS unit with a true RS-232 serial port. Look for higher-end aviation, marine, or surveyor models; these units will have external antenna SMA connectors, serial ports, and configurable NMEA output settings. Yet they will be free or cheap if they are sufficiently old.
Should I toss my RG-59 coax? jazzop on 29/8/17
I am sorting out my odds and ends of cables and components in an attempt to maximize storage space and identify what I have on hand. I haven't been able to find any reason why keeping my RG-59 coax cables would provide some advantage over the miles of RG-6 I also have. Is there any application (other than needing a tighter bend radius) where RG-59 would actually be preferred over RG-6?
Antennas inside fabric-covered structure? jazzop on 7/9/16
I'm looking for a clever way to run a long wire or loop antenna (20m or more), and I want to explore this possibility:

I'll likely be building an aircraft hangar, and one option is a fabric-covered aluminum frame. This manufacturer supplies the military with these hangars out in the sandbox, so we aren't talking cheapo materials. Let's assume for now that the fabric is RF-transparent (I'm still awaiting technical data). The structure will be about 50'x75', with a peak of about 22'. Obviously this gives rise to the clever notion of installing antennas inside the roof of this thing.

I could suspend antennas from the upper structural crossmembers. Or I could run a wire antenna along the peak, between the frame and fabric. Or I could insulate the junctions between various frame components (they are bolted, not welded) that happen to be the right length for a particular band, and turn those segments into antennas themselves.

I'm not very knowledgeable about antenna design for any band other than 2m, but when I build this place I want to get into MF, HF, LF, etc. Tell me if I'm identifying the right concerns here:

1. Effect of the structural frame network on antennas inside (Faraday caging)?

2. Reflectivity and conductivity of the structural frame on antennas mounted on or near it?

3. Positional angle of the frame members realtive to the desired radiation pattern, if it's feasible to actually turn them into antennas themselves?

4. Impact of cross-sectional shape of the frame members (e.g., box-section, I-beam, asymmetrical extruded), if they are to be used as antennas?

5. Effect, if any, of the exact aluminum alloy? Anodization? Coatings?

6. Of course, the fabric's RF transparency must be determined.

You might wonder why I don't just build a tower; well, the aircraft hangar should give away the fact that this is a private airfield, so towers aren't exactly kosher. Max height allowed of any structure or tree is 50'. I could put a short mast on top of the hangar and run the long wire antennas back to the ground. But I like the idea of keeping all my antennas inside the shelter for easy maintenance, concealment, and protection from the elements. So unless there is a clear performance penalty for doing so, I want to explore it further.
Ham-friendly tips for whole-house rewiring? jazzop on 7/9/16
I want 3-phase for other reasons, primarily for high-efficiency compressor motors and enterprise-grade blade servers. I'm curious if the nature of 3-phase has any beneficial effect on nearby radios; I imagine 3-phase motors probably put out much less noise.

What about running separate DC bus from on-site power generation to the electronics that use DC anyway? Seems like eliminating AC inversion/conversion steps would theoretically be beneficial.

If dedicated DC isn't the way to go, how about an AC bus on a different voltage? 50Hz vs. 60Hz? I'd have to check the NEC, but I don't see why I couldn't have some branch circuits with international outlet formats to prevent misconnecting US-spec plugs. Auto-switching power supplies on electronics make this a simpler task than it used to be. I even own a bunch of EU- and Japanese-market electronics (A/V gear, not radios), so I have a legit reason to install such circuits.

The house will have a really deep, really large copper ground rod for single-point grounding of electrics and lightning arrestors. Chassis grounds will also go to it. I've already gotten the ground loop lecture from enough people that I understand the importance. I downloaded the Navy manual on station design, and it really gives a lot of attention to the grounding system.

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