McDuory Outdoor / Attic Antenna Review

Make: McDuory (www.mcduory.com)

Model: UHD-3968

Type: LPDA (Log Periodic Dipole Array (staggered))

Element Type: Split 1/2 wave resonant elements (nominal 72 ohm impedance)

Impedance: 75 ohms direct feed

Balun: Not included, use snap on ferrite

Covers:

• VHF Channels 7 - 13 (170 - 230 MHz)
• UHF Channels 14 - 79 (470 - 860 MHz)
• Pan American TV Frequencies

Buy from Amazon ($37 17-Mar-25) - https://www.amazon.com/dp/B07JMDZZWM 

Installation

Notes

• Used Penetrox joint compound -
• Grease boom brackets (Booms form the feed/phase line)
• Element ends - where the longer elements are pushed into the brackets
• Screws - remove, apply some penetrox, gentle 1/4 turn once slack is taken up
• Lanocote around F connector and connection to boom, around black element brackets / boom to weather proof from rain/water
• Added snap on ferrite clamps (Fit RG-6) to form a 1:1 balun (Isolate coax shield outer)
• Used https://otadtv.com/tvtower/ to locate local stations , and compass to pick average direction / best average for all stations.
• The included RG-6 is probably "OK", they do include fitted F connectors with drip covers. Since the coax is no-name-band its likely low quality, may need to upgrade to name brand quality RG-6 if there are signal level problems.
• The antenna will last much longer (years)
• Mine is mounted under a porch where it is also out of the rain
• Attic installation would also be preferred if it works
• Dual boom LPDA is a good tried and true electrical and mechanical design, directional, broad band, with direct match for coax

On Air Test / Performance

Found all local TV stations (digital) between channels 7 and 26 up-to 25 miles away. Enough signal to run 3 to 4 TVs with a splitter and quality RG-6. All the usual suspects, ABC, CBS, Fox, PBS, NBC etc. The HD channels look great (HD can be better than you think!).

Conclusions 

For the price the materials are of good (light duty) quality, with all mounting hardware supplied.

Since it uses resonant 1/2 wavelength elements it is fairly compact for a VHF high band + UHF TV antenna.

It may not fare well in salt air or humid wet climates,  Better suited to attic or semi protected installation (out of the rain). With Penetrox and Lanocote (as appropriate) it should do well for a number of years.

An HD version using better materials for 2x the price, water-proofing, and a balun would be a welcome option.

December 2024 Antenna Designs

After having relocated back to North Pole AK in the Alaskan Interior (15 miles south of Fairbanks) last summer, I got the station operational with the same doublet (except 90 ft flat top at 65 ft, ends hang vertical 20 ft), and three element LFA Yagi for 6m at 30 ft height.

Since we have two acres and it's the middle of winter, time to think about antennas!

Goals

• Antenna feeder / lightning grounding points are away from house.
• Antennas are located away from house as far as reasonable.
• Lower and upper HF band antennas.
• VHF / 6m array.
• IRLP node antenna mast mounted (currently in attic).

IRLP Node 

Relocate IRLP node to shed, Diamond X-50 on shed VHF mast.

Plan to eventually convert to 70cm to free up local 2m VHF FM use.

Low Band DX Delta Loop

80m inverted delta loop, vertically polarized, with 120 ft horizontal top at 65 ft.

Open wire fed to remote auto ATU.

Post on Blue Sky with Low Band DX Delta Loop patterns on 80m and 40m:

https://bsky.app/profile/lonney9.bsky.social/post/3lcv5bk2f5k2b

Model: https://github.com/lonney9/Antenna-Models/tree/main/HF/Basic

Held up with trees, need tensioning system that handles tree movement in wind.

Upper HF - Vertical Doublet

20m through 10m to remote auto ATU.

https://lonneys-notebook.blogspot.com/2021/03/40-ft-center-fed-vertical-40m-10m.html

VHF / 6m (50 MHz)

• Two stack of three or five element LFA Yagis for 6m.
• Currently have a three element
• 20 to 30 ft mast bracketed against shed.
• Winch up/down system on hinged base.
• Mast mounted 6m low noise pre-amp.

Antenna Shed (existing building)

• Feeders go-to shed.
• Grounding system at shed.
• Remote ATU and antenna switching networks.
• Coax and control cables buried to house.
• IRLP node relocated to shed.

Feeders Go-To Shed

Balanced lines from Delta Loop and Vertical Doublet go-to shed.

Remote ATU and Antenna Switching Networks

Stockcorner JC-4s remote ATU located in shed.

JC-4s is a dual memory tuner with reversible un-balanced output polarity. Intended for dual antennas with dual memories which are switched in RX mode so the connected antenna is always matched on RX as well.

Delta Loop and Vertical Doublet independent switching networks and 1:1 balun in-front of ATU. This is in addition to the JC-4s internal A/B mode.

Grounding System at Shed

• Lightning arrestors for balanced feeders and coax at shed entrance.
• Several 8 ft ground rods.
• Shed ground system bonded to electrical service entrance - AWG?
• House entrance grounding point.

Cable Runs

• Trench with conduit.
• LMR-400 and control cables.
• Priced vs loss savings of LMR-600, not worth it for 50 MHz and below.
• Ground bonding wire.

Grounding / Entrance Panel

Check / upgrade grounding at service entrance (NEC code) as needed.

Entrance panel into garage (grounded), then to shack above.

Low Noise RX Antennas

Get the K9AY loop operational.

Maybe get Active Antenna Kit from LZ1AQ - http://lz1aq.signacor.com/

More details to come..

Cebik Pages Update

https://www.antenna2.net/cebik/

As noted, things have been tidied and improved, updated to syntax correct HTML with a single CSS file, broken links fixed, some missing content found and added back in. A useful addition is the topics index which makes it easy to find all related pages on a subject, and see them all listed in one place.

I started working on this a few weeks ago when I learned that ON5AU who hosted the only known complete copy had become SK.

After I started looking at the Cebik pages, one thing lead to another, and the end result was significant update which I think was needed considering how useful this is to many.

Happy Holidays!

18 / December / 2024 Update

Now available on GitHub:

• https://github.com/antenna2

Clone, fork, or download ZIP archive from Green code button.

Happy Holidays!

MacLoggerDX Logs Backup Script

MLDX-Backup is a backup script I wrote for MacLoggerDX.

• It gracefully closes MLDX.
• Creates tgz archive (gzipped tar file).
• Excludes .DS_Store, debug files, QSL card images, ADIF conformations log.
• Keeps the last five backups (removes oldest when new backup is created).

Also includes information on how to manage things with iCloud drive Documents and Desktop syncing if used.

JS8Call Band Hopping Script

Recently someone asked on the JS8Call group about band hopping or cycling through several bands on a 10 minute cycle.

Jordan the author of JS8Call suggested using the API to do this.

I decided to see what was around and found this well documented js8net API library, with that I was able to interact with the API from the command line, and could read and set the frequency.

Python is not something I'm familiar with, so I used ChatGPT to help me write a python script that would cycle through a list of frequencies changing to the next one every few minutes.

The result was JS8BandHop, a fairly simple Python script.