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Author Topic: AO-7 (Oscar 7) Minimum Equipment Requirement  (Read 583 times)

W9AC

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AO-7 (Oscar 7) Minimum Equipment Requirement
« on: February 17, 2021, 11:28:24 AM »

I last worked AO-7 back in 1975-1976.  My best friend in high school and I used a Yaesu FT-221 for the uplink and a Yaesu FT-101B for the Mode A  10m downlink.  I did the orbital computations with a then-new HP-25 calculator.  I don't recall any link issues. 

I recently purchased an Icom IC-705 and Arrow Antennas model 146/437-10BP.  I have yet to hear AO-7.  In fact, I have yet to hear anything on 2m from any satellite but my main focus has been in trying to hear AO-7.  I'm using the SatSat and GoSatWatch iPhone apps to watch tracking. From the AMSAT Status page, it appears that AO-7 is mostly locked in Mode B (UHF/VHF) at the moment.  I know that AO-7 is a "daylight only" sat.

Before I order a second IC-705 for full duplex operation, I need to know that any of this is worth the time, money and effort.  I'm not too interested in the FM repeater sats. 

Am I under-equipment for AO-7 Mode B? 

Paul, W9AC

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WE4B

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #1 on: February 17, 2021, 12:17:11 PM »

I use two 817s and an Arrow for Mode B of AO-7. Your 705 isn’t full duplex so you’ll really need another radio to go along with it. I can generally use the satellite with about a watt of power. It’s a fun satellite to work and allows for some fun DX opportunities.
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W9AC

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #2 on: February 17, 2021, 12:52:20 PM »

Thanks for the feedback.  AO-7 just passed my QTH and peaked at 89 degrees elevation.  I finally heard several strong CW stations although with slight chirp.  I'm now motivated enough to purchase a second IC-705 to get full duplex. 

I do need to figure out a way to put the Arrow antenna on a small tripod with the ability to manually rotate it on X,Y, and Z axis.  My arm got kinda' sore holding the antenna and I need three hands.   Ideas, anyone?

Paul, W9AC
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WA6BJH

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #3 on: February 17, 2021, 01:02:13 PM »

I think Arrow sells a tripod mount.

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AF5CC

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #4 on: February 17, 2021, 06:53:50 PM »

I hear and use AO7 just fine with a Cushcraft A270-10S dualband yagi, with 5 elements on each band and no elevation on the antenna.  The XW-2 satellites are probably the easiest to hear on 2m as they have a booming downlink.  I have used them before with just a 1/4 wave mag  mount mobile whip.

73 John AF5CC
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N7WE

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #5 on: February 18, 2021, 05:57:59 AM »

I think Arrow sells a tripod mount.

This from the Arrow website:  Under the foam grip, the boom is drilled & tapped with a 1/4-20 hole for most camera tri-pods.
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W9AC

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #6 on: February 18, 2021, 06:30:57 AM »

Thanks.  I'll give it a try.

Paul, W9AC
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KD9VV

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #7 on: February 19, 2021, 11:14:15 AM »

Why a second 705?
For a bit more you could purchase the IC 9700?

Just to add, RS-44 has a great downlink and it's high orbit minimizes doppler corrections.
I use SatPC32, seems to work very well for me with the 9700.
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W9AC

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #8 on: February 19, 2021, 11:40:05 AM »

Why a second 705?
For a bit more you could purchase the IC 9700?

Just to add, RS-44 has a great downlink and it's high orbit minimizes doppler corrections.
I use SatPC32, seems to work very well for me with the 9700.

Thanks for the tip about RS-44.  The second IC-705 is for full-duplex transmission.  I just sold an IC-9700 to purchase the IC-705 for portable operating.  The 9700 wasn't going to do it for me.  Two 705s in a backpack allow for full duplex and long battery life.

I'm nearly finished with the tripod antenna mount for the Arrow 146/437-10BP antenna.   I purchased a 3 ft. length of 1-inch dia. 6061 aluminum tubing, clamp-mount ball bearing, and a pair of 1 lbs. donut barbell counterweights that can be adjusted on the tubing for best balance with a 10 or 14 element Arrow antenna. 

The tripod allows for easy azimuth and elevation changes but not the ability to optimize polarization with rotation.  That's the purpose of the bearing.  One hand makes all three axis changes without too much difficulty.  I'll know for sure when used out in the field.  What works in the garage may not work in practice. 

Paul, W9AC

       

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N6MST

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #9 on: February 23, 2021, 04:03:57 PM »

I'm nearly finished with the tripod antenna mount for the Arrow 146/437-10BP antenna.   I purchased a 3 ft. length of 1-inch dia. 6061 aluminum tubing, clamp-mount ball bearing, and a pair of 1 lbs. donut barbell counterweights that can be adjusted on the tubing for best balance with a 10 or 14 element Arrow antenna.

DETAILED PICS!!
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W9AC

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #10 on: March 12, 2021, 10:03:40 AM »

Photos of the completed Arrow antenna mount are posted on my QRZ page. 

I abandoned the pipe mount and came upon the idea of using a single bearing attached to a 4" x 4" aluminum plate and joined two square boom pieces together.  A camera quick-release adapter is fastened to the plate's bottom and connects to the tripod. 

To make this work, I ordered three feet of 0.75-inch square aluminum tubing (same size as the Arrow boom) and a 10-inch section of 0.625 square brass tubing that's used to join the aluminum boom pieces together.  The Arrow antenna simply plugs onto the brass tip.  No fasteners required. 

This mount gives me fast X,Y, and Z control while seated.  It's definitely not as elegant as the servo-controlled systems I've seen but I would rather have manual control of rotation to quickly optimize polarization changes. 

The counterbalance weight is a galvanized "structural nut" that slides onto the new boom.  I had ordered a few nuts but one works fine with the smaller Arrow antenna.  Balance is achieved by sliding the weight, then holding it in place with the two U-clamps seen in the photos. 

The new back boom could be cut shorter but I'm reluctant to do so until I try the larger Arrow antenna.  Then if needed, it can be cut shorter. 

Link to my QRZ page:

www.w9ac.com

Paul, W9AC
 
« Last Edit: March 12, 2021, 10:25:30 AM by W9AC »
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WE4B

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #11 on: March 20, 2021, 06:47:23 PM »

I was thinking about this thread today while I was working AO-7 in Mode B.

Today, I made several contacts via AO-7 using nothing but a couple of FT-817s and a handheld Arrow antenna. I had the transmitting FT-817 set for 1 watt although it was probably less since the battery wasn't fully charged. I was able to make several QSOs with stations in America and Canada.

Very minimal hardware and wattage is required to utilize AO-7, which is underused. AO-7 has allowed me to make contacts across the Atlantic into Europe many times.

RS-44 is also fun for DX but, for me, AO-7 is more fun just due to its history.

73!
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N4UFO

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #12 on: March 20, 2021, 11:33:25 PM »

You want fun? Work AO-7 from the middle of the Nevada desert with and Arrow and pair of 817s and give rare grids to several hams that missed you on the 'more conventional' birds. Now that was fun.  :)

https://www.qrz.com/db/N4UFO/P

 (scroll down)  worked AO-7B from DM07/08/17/18 grid corner and DN01/11 gridline
« Last Edit: March 20, 2021, 11:38:44 PM by N4UFO »
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WD9EWK

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #13 on: March 21, 2021, 11:13:43 AM »

You want fun?

Doesn't take much to work AO-7 in mode B. Like Kevin, I've taken my radios all over to work this satellite - and the others...

During the ARRL Centennial Convention held in downtown Hartford in 2014, I had a couple of demonstrations using AO-7 outside the convention center. First one was on 17 July, at the end of a day-long seminar on amateur satellites...

https://www.youtube.com/watch?v=G5TjXbuLv5s

That video combined the downlink audio, as I didn't have a proper video made of that demonstration. Two days later, another demonstration on AO-7. This one was captured in a video:

https://www.youtube.com/watch?v=BHd91H_t88o

I have worked AO-7 from locations across the continental USA, and from 3 foreign countries. I don't have any videos of working AO-7 from Canada, but here's one from 2010 when I operated near a baseball stadium in the Mexican border city of Mexicali (across the border from Calexico and El Centro CA - east of San Diego and Tijuana):

https://www.youtube.com/watch?v=eNUy-c1ptdg

This was back when foreign hams could get permits to operate in Mexico. Unfortunately, those permits aren't being issued to foreigners anymore, plus it isn't as safe to be wandering around Mexico with radio gear now as it might have been 10 or so years ago.

In 2011, I took a trip to Melbourne and Sydney in Australia. Most of my operating down there was on SO-50, but I was able to get on AO-7 from a Melbourne suburb and work stations near Sydney and Brisbane. Video is a combination of pictures and the downlink audio:

https://www.youtube.com/watch?v=WM6rXgFiJJY

Although I still take two FT-817s when I go out with my satellite gear, I have been using an Icom IC-R30 receiver for the downlink lately. The IC-R30 does well with satellite downlinks, and will record to a microSD card I have installed. I also use the all-mode receiver in Kenwood's TH-D74 on occasion. And I have used SDR receivers, connected to a laptop or small Windows tablet. Lots of options for the downlink receiver, but I almost always go with an FT-817 for the uplink.

73!
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Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/ - Twitter: @WD9EWK or http://twitter.com/WD9EWK

WE4B

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Re: AO-7 (Oscar 7) Minimum Equipment Requirement
« Reply #14 on: March 21, 2021, 10:43:17 PM »

I wish more people would use AO-7 but since it's not the latest, greatest thing, it goes underused. I try to use it on every pass in which I'm able to do so. It's a zombiesat and there's no way to know how much longer it will be operational but it's so easy to use and provides awesome opportunities for DX. There are a lot of people that rove in the U.S. but not all of them utilize AO-7. I wish they would as there are passes every day that cover the entire, CONUS which would give everyone an opportunity to make contacts. Viva AO-7!
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