Satellite radios: Don’t lock those VFO’s on LEO’s (satellites)

DISCLAIMER: This entire blog post is focused on manually tuning your satellite radio to make contact via linear transponders (SSB/CW.)  If you are using computer control of your rig for Doppler Shift correction, some of the comments  below will not apply.

Most popular satellite radios such as the Kenwood TS-2000, Icom IC-910h, and the Yaesu FT-847 offer a mode to “track” satellite frequency movements.  There are normally two types of tracking, Normal and Inverse.  Your rig or software may refer to Inverse as Reverse.

Inverse tracking moves your uplink and downlink frequencies in opposing directions.  If you move one VFO up 10 kHz, the other VFO will go down in frequeny 10 kHz.  The majority of amateur satellite transponders in orbit utilize inverse tracking.  Inverse tracking is the most common practice.

Normal tracking moves your uplink and downlink frequencies together in the same direction.  Only one satellite operational today does this – AO-7 in mode A.  (note: Mode B is inverse)

It is important you have the correct tracking mode selected for each satellite before you go any further.

Most of the manuals for true satellite radios explain how to find your own uplink or downlink signal.  I won’t go into that on this blog post.  I want to cover an important topic: DO NOT DEPEND ON YOUR SATELLITE RADIO’S LOCKED VFO’S TO KEEP UP WITH DOPPLER SHIFT.  I intentionally bolded and capitalized that entire sentence.  It is very important.  You will always need to make manual adjustments as long as you aren’t controlling your rig’s VFO’s by computer.

The radio’s internal VFO locking does not really have anything to do with Doppler shift.  It simply locks the VFO’s so that they move equally with each movement of the main VFO knob.  This will not properly tune your station to the same frequency as another station on the satellite passband.

If you try to have a QSO with someone while your VFO’s are locked, you will look like a lid because every time you move your VFO knob, the uplink/downlink frequencies are technically moving away from each other in an unnatural manner, not how Doppler shift is affecting the uplink/downlink relationship.

It’s fine to lock the VFO’s and move to another part of the passband but it is not sufficient for staying in one place and having a QSO.  Once you “land” somewhere, unlock and tune the sub or main band VFO depending on the satellite mode (V/U aka J or U/V aka B.)  This is where the  Updated One True Rule comes into play.

Remember, we tune the higher of the two frequencies.  Examples:
AO-7, AO-73, XW-2 linear transponders: tune uplink
FO-29: tune downlink
If you lock the VFO’s, you will be tuning BOTH!
(that’s okay if you are using computer control and it’s done automatically and properly)

Final thoughts:

I highly recommend reading “The One True Rule for Doppler Tuning” by Paul, KB5MU and the updated “Bringing the One True Rule of Doppler Tuning into the 21st Century” by Alan, WA4SCA.

Buy a copy of AMSAT’s “Getting Started With Amateur Satellites.”  It covers this topic well and includes the above two abstracts.

More fun with the Short Arrow

This week, I decided I’d try out some new LMR-240uf jumpers that had arrived. Most of the jumpers I use in my portable station are 10′, either the LMR-240 (stiffer/solid center) or the LMR-240uf (UltraFlex, stranded center.)

For a few years I’ve really loved the stiffer LMR-240 and it’s never been a problem.  However, at a friend’s insistence I went ahead and made some LMR-240uf jumpers.  I’ve yet to notice a big difference however, I’d probably use the solid center if I was making some record-breaking attempt.

Since there was a LilacSat-2 pass rising, I decided to test the jumpers on that pass from my patio, facing east.  Here’s the catch: I wanted to use a single Yaesu FT-817.  Yes, it would be semi or “half” duplex (not my favorite/recommended,) but it was a good chance to test both jumpers.  Before I used them on RF, I did do a quick continuity check with my VOM to make sure the cables had no short.
How can I test both jumpers on the FT-817 without using the Arrow diplexer you ask?
The FT-817 has two antenna ports.  Simply configure UHF for one port and VHF for the other.  You do this by going to the band and selecting the antenna in your menu: Front or Rear.
Since both jumpers are terminated with BNC males, I did need to use an adapter on the FT-817’s rear SO-239.  It’s not my recommendation to use adapters since they are prone to failure and can sometimes be lossy (especially cheap ones.)  

 

All in all, it was a quick and easy test.  I made 3 contacts on this pass: Tennessee, Ohio, and Colorado.

Recent AO-85 Observations – 17 February 2016 AMSAT-BB Post

For the past several days, I have observed the following:

– On ascending passes, I can activate the transponder at AOS very easily.  Either polarity V or H works.

– Previously, I needed 10-15 degrees at times on ascending passes to activate the transponder.  As I approached TCA, the challenge getting in always went away and I could get into the transponder easily.

– Descending passes have never been an issue for me. I could access the transponder at AOS and activate the transponder as low as 0.1 degrees elevation.

– Downlink receive polarity seems to flip almost constantly or be equal at times.  I’m running a V or H antenna configuration (not RHCP or LHCP.)

– Suspected reason is the spacecraft’s spin rate has changed with it now in constant sun.

– As a result I’m hearing some newer stations working AO-85 with handheld transceivers.  I’ve worked 2 new stations in the last 2 days who emailed me directly after the pass stating they were seeing some success with an HT.

Omnis, Dipoles, Eggbeaters, Moxons, Turnstiles for Satellite Antennas

I am not a fan of omni antennas for the current LEO satellites. The eggbeater or moxons are marginal performers at best.

Short, quality feedlines and RX preamps are good ways to minimize ineffectiveness of omnis but there’s no silver bullet.

If you have no other choice but omnis, you may find yourself limited to certain satellites** and certain passes. SO-50, for example, is not going to be favorable. Compensating for lack of hearing ability by running full power won’t make you many friends.

Working satellites on an almost daily basis, one can often identify an eggbeater or omni user by their inability to hear a very strong signal from the satellite.  Usually these operators have a strong signal but can’t hear themselves or another strong station calling them.

A set of small yagis at a fixed elevation with an azimuth rotor will yield far better results. The trick is not using longer, high-gain yagis. You’ll have more beam width with smaller ones. Considering what many stations achieve with an Arrow or Elk antenna (7,000+ km contacts,) bigger isn’t always better.

Bottom line:

  1. Omnis are okay as long as you understand the shortcomings.
  2. You may make some contacts with omnis.  Try it but don’t invest much money or effort into them.
  3. Omnis are an okay choice if you have no other option but to eliminate the need for a rotor.  I realize sometimes there are operational constraints.
  4. Don’t expect consistent AOS to LOS performance with an omni unless you have a great view of the horizon and sky in all directions and a very low-noise RF environment.

** The best satellites for omni’s are likely going to be mode B (U/V) SSB transponders like AO-73, XW-2A, XW-2C, XW-2F. AO-7 will be okay at times depending on health and elevation of pass.  FO-29 will be marginal if you pick the right passes.

2015 Satellite Operating Stats & Review

Some satellite operators on Twitter (N8HM, AA5PK, WD9EWK, KA4H, and others) have been posting their operating statistics from 2015.  I decided I’d “get with the program” and generate some stats from my station as well.

These numbers include all contacts made by W5PFG from both portable and at home.

Obviously I favor SO-50 and FO-29.  There’s one simple reason: that’s where the action is!   They are both relatively easy to work portable since you can fix your uplink and make minimal changes to the downlink over the course of a satellite pass.

SO-50 is our most consistent “easy sat” today.  It is operational 24/7 and it’s performance is very stable.  It is still difficult to hear by some with sub-par and mediocre stations.  Whips are for lids. Minimal portable gear is an Elk or Arrow for effective QSO’s.

FO-29 remains my favorite satellite in general.  Great footprint, easy to work, very reliable.

I think the transponders on XW-2F and XW-2A are very strong and stable and I can work both at negative elevations frequently.  RIP XW-2E.

AO-73 is a fun bird to work but a lot of people are put off by its frequency drift. Personally, that’s not an issue for me and I will always utilize AO-73 on portable trips when it’s available.

AO-7 remains a workhorse but is very susceptible to people running far too much power and causing the transponder to pulse.   CW stations should take extra precaution to run the absolute lowest power available from their stations and even consider attenuation in some cases.  The mode A/B switching does deter some from using it regularly but it’s a solid bird and I’m grateful to have it.

LilacSat-2 is a nice satellite. It’s a little weaker than SO-50 but is very consistently performing when it is activated. That in itself is the biggest issue — scheduling. The sporadic activation of the transponder has turned a lot of people away.  It sounds great and operates well — when it’s on.  Hopefully the ground control team with move to a more consistent schedule or make it available 100% of the time eventually.

As we see more Fox-1 series satellites from AMSAT, I think that will change.  AO-85 is more difficult to work that we’d all hoped and I’m sure the engineering team is working to address the issues in Fox-1C, Fox-1D, and Fox-1B.

And finally, ISS packet is still a reliable way to make 2m-only contacts via satellite.  A lot of stations are over-dependent and confident on their vertical antennas. The worst part of ISS packet is all the moronic lids who leave their station beaconing unattended 24/7. Some things will never change.

Onward to 2016!

Organizing my W5PFG/P Satellite Station for Portable Trips

One thing on my list for a while has been to acquire and setup the right size carrying cases to travel with and protect my investment in portable equipment.

Over Christmas I acquired a Pelican 1500 (yellow, as shown below.)  The Icom IC-821h fits perfectly inside along with the microphone.  I could probably make room for the power cord but at the moment, my cord is a bit long and doesn’t coil compactly.

The second case is a Plano Protector Series #1404.  It is not waterproof or nearly as rugged as the Pelican case but it holds all of my accessories and adapters needed for /P securely.

Aside from my coax jumpers and antennas, everything fits neatly into each box.
Box 1:
  1. Icom IC-821h Transceiver
  2. Icom Microphone

Box 2:

  1. Heil Dual Pro-Micro Headset
  2. Heil hand-trigger PTT
  3. Heil adapter for IC-821h
  4. Sony digital recorder
  5. Spare batteries for digital recorder
  6. Icom power cable
  7. Spare power cable and cigarette plug (for emergencies)
  8. Belkin 5-way audio splitter (to take audio out and feed to headset and digital recorder)
  9. Compass
UPDATE: One reader pointed out that my use of the Belkin 5-way audio splitter was hypocritical since I gave him a hard time for using one in his portable setup.  I must confess, he’s right.  I normally do not need to split audio more than 2 ways (to headset and recorder) but sometimes it’s convenient to be able to have an audience listen. 

Central States VHF Society CS-VHF Reverse VUCC Award – Satellite

After operating from over 100 different grid squares, I decided it was time to apply for the Central States VHF Society (CS-VHF) Reverse VUCC Award.

Arliss, W7XU checked my cards and issued the award last week, December 9, 2015.

Thank you, friends, for all the great QSO’s while I’ve been on the road!

The award is issued in increments of 25 starting at 100.  I’m now at 117 grids but don’t really plan on increasing my endorsements any time soon.

Say Hello to My Little Friend – The short Arrow

Reach for the skies!
Long a trick passed down from one roving guru to another, I have decided to share my recent experience with the home-brewed “short Arrow.”  I first heard about this from my friend Wyatt, AC0RA.  Others over the years have made this same, basic hack.
Essentially my original Arrow II is unmolested.  However, if you wanted to start with a solid boom Arrow you could easily saw boom to cut off the end 4 elements.  
I took some 3/4 aluminum tubing and created a new boom.  You can buy a 6′ piece of this tubing at Lowe’s for approximately $20. 
Using the original Arrow boom as a guide, I made holes in the new boom to match alignment and spacing of elements to the factory-made one.  Using a drill press, I made the 6 holes required (2 for 2m, 4 for 70cm.)  The original Arrow elements fit perfectly through my new home-brewed boom.
Photo of new short Arrow, old boom (in it’s 2-piece travel configuration) and excess 3/4 tubing.

  

Ready to test the short Arrow on a 65 degree-elevation FO-29 pass.

The short Arrow performs great, assuming you have a clear view to the horizon.  I was able to work FO-29 AOS to LOS.

During a recent trip to Ohio for the AMSAT Space Symposium, I used AC0RA’s short Arrow to work a 3 degree elevation SO-50 pass.  It worked very well in open farm country.

The best part is, I can assembly my original “normal” Arrow using the boom.  I have the option of full or “mini” size.

All in all, this modification goes to prove “bigger isn’t always better.

2015 AMSAT Space Symposium Wrap-up

In October I attended the 2015 AMSAT Space Symposium in Dayton, Ohio. It was held at the downtown Crowne Plaza Hotel.  It was a well-attended event and the roster was packed with very technical presentation.  Great fellowship is one of the many reasons I attend these events.

Entrance to the Dayton Crowne Plaza from their parking garage.

Working satellites from AC0RA’s pickup truck. He’s holding his shortened Arrow.
We operated from the EN70/80 line, EM89, and EM79 before the Symposium.

N8HM working SO-50 from the rooftop of the parking garage.

Enjoying the Friday evening auction.

Saturday lunch at the Dublin Pub (Dayton)

Giving a demo of my remote-controlled satellite station from 13th floor lounge of hotel.

Just a few of the operators who attending this year.
L-R AC0RA, KO4MA, W5PFG, WD9EWK, N8HM, K8BL
It was nice to meet WB8RJY and K8OE who were also in attendance!
And I almost forgot my friend and fellow Texan Glenn, AA5PK.

Infamous “Corner Booth” at Denny’s approx midnight. 
 L-KO4MA, WD9EWK, R-N8HM, AC0RA, W5PFG

My Thoughts about the "Alaskan" Arrow 146/437-14

DISCLAIMER: I don’t want this posting to come across as being “Anti-Arrow.”  I love and use the normal 146/437-10 LEO satellite antenna.  I have two of them! 

However, I do want to share my thoughts about the Alaskan Arrow, model 146/437-14.

J. Boyd, NI3B, recently made this comment on the AMSAT-BB email list about the Alaskan Arrow:

Pros: Having those extra elements makes it so much easier to lock onto a
bird and reach it with less power.

Cons: It weighs as much as a baseball bat. Holding one of those things
up in the air for fourteen minutes and your arms will look like Popeye
the Sailor Man at LOS. You're going to need a tripod, or at least a
camera monopod to brace it against the ground.

Personally, I wouldn’t recommend buying an Alaskan Arrow if you already own a regular 146/437-10 Arrow. I recently bought one and have already sold it after some field trials.

Basically, it works well. Nothing is wrong with it. For $140 without the diplexer, it’s a bit steep. I think the value proposition is not quite beneficial enough.

For someone who has a regular Arrow, there is little noticeable improvement for 95% of all passes and operating. My normal Arrows can work every current bird from AOS to LOS assuming I have a clear path to the horizon.

If you do not own an Arrow antenna, I would suggest buying the 146/437-10 model.  You can easily hold this antenna in your hand or easily mount it to a tripod if you desire. Mounting the Alaskan one to a tripod is do-able but you’ll definitely want some counterweight.

Update: December 8, 2016: One good reason to buy an AK Arrow for your “first” Arrow is that it can be broken down and used in sections: one or two-thirds the original size.  The 1/3 sized AK Arrow is very similar to my favorite short-Arrow configuration. Therefore, if you want to spend the extra dollars for an AK Arrow you do buy yourself some added versatility.

As pointed out by the gentleman mentioned above who claimed “Popeye Arms” are a side effect for using this antenna, he is spot-on. I am not a fan of using tripods and the Alaskan Arrow almost forces you to use one. The Alaskan Arrow is unwieldy and not as easily portable as a regular Arrow.

Having made several thousand contacts with an Arrow in the field, I cannot justify using the Alaskan Arrow as a replacement. I bought one thinking I would use it on our RV adventures.

I’m not dismissing there is extra gain in an Alaskan Arrow. KG5CCI made some great transatlantic contacts with his in 2015.  However, bear in mind that contact distances over 7,000km have been made for years with the regular Arrow.

I’m a fan of the standard Arrow LEO antenna. For extreme DXing, home/permanent mounting, I’m confident the AK Arrow works great.

A great collection of Arrows at the 2014 AMSAT Space Symposium