Sunday, December 3, 2017


This post is a quick picture of the moon since it is always a simple target, when it is up and a discussion about focus performance.


Autofocus was run and resulted in 1/2 Flux diameter (HFD) of 5.96pixels.
  • The half-flux diameter is the diameter in pixels that contains half the energy in a star image.
  • The question is, is a 1/2 Flux diameter of 5.9 something to write home about or be improved upon?
  • It should be possible to calculate what the theoretical HFD of the optical and CCD system is.
  • It should be possible to combine this with the seeing and estimate expected HFD. 
  • Then we would know if we are impressed by a HFD of 6.
  • A sufficient reference to begin with is Link. I have calculated the Airy pattern for the EDGE 11 SCT. It is presented below. Compared to the Celestron "glossy spec sheet" this calculation is in agreement with the 0.5arc-sec specification.

    Airy Disk for 11" EDGE SCT
  • The above result was converted to total flux in a diameter by integrating and scaled to CCD pixels.
  • HFD for 11" EDGE w/ STF8300 CCD
  • From this result the HFD of the optical system should be 0.7arc-sec.
  • Seeing is a measure used to quantify stability of star light in the eyepiece or camera. The most excellent Canadian link has a good and relevant description of seeing.
Seeing w/ Scope and CCD
5/5 or V
less than 0.4"
Less than 0.9”
1.4 pixels
4/5 or IV
~ 0.4-0.9"
Up to 1.2”
2.1 pixels
3/5 or III
~ 1.0-2.0"
Up to 2.2”
3.7 pixels
2/5 or II
~ 3.0-4.0"
Up to 4.1”
7.1 pixels
1/5 or I
more than 4"
More than 5”
8.8 pixels

  • The last column in the table above is a combination of seeing and theoretical optical performance. It was calculated by taking square root of the sum of the squares of seeing and optical performance. Expressed in arc-second units and pixels.

To return to the original question, best focus was 5.9pixels HFD and this corresponds to poor seeing. I do not recall the seeing forecast for the evening of the image. It is possible that seeing forecast was Poor and so the 5.9pixel HFD may be reasonable.

I will pay more attention next time.
    Since the moon is so bright a Ha filter was used to cut brightness and a 1mS exposure produced 3/4 full wells.

    • Focus MaximDL 1/2 Flux Dia. = 5.93
    • Exposure Control MaximDL Ha 1x1 1x0.001sec
    • Guiding Unguided
    Image Processing
    • None

    Tuesday, August 16, 2016

    Life is good when you have time to grab some photons.

    Just a quick post

    • Object M16

    • Focus             MaximDL
    • Exposure Control  MaximDL L 1x1 10x200sec, RGB 3x3 10x100sec
    • Guiding           MaximDL

    I must say, I think I have found the setup I like. :)

    Monday, September 23, 2013

    5ft Hole, -200lb Rock, +6000kg Concrete, 48ft Tower, 3element Yagi

    Earlier on in the summer the tower plans started with selecting the site. I chose "up" behind the house because this would give an extra 8 to 10ft and would help get the antenna above the surrounding tree line.

    4ft done, one more to go.
    The hole digging went OK for the most part. It just took time and patience.

    200lb Rock
    The one "event" of note was the removal of what must have been a 200lb stone that some glacier must have left behind.

    The concrete was supplied by the folks at Cruickshank out of Kemptville.


    I used a plumb, twine and a sledge to help the tower true while the pour happened.

    The tower went up in sections 6 8ft sections to a height of 48ft.

    After operating the Seppir on the garage roof for a few weeks, to make sure it was all in working order it came time to hoist it up the tower.  The antenna weighs about 60lbs and is 39ft tip to tip on a 16ft boom.

    Raising the antenna
    Getting the steppir on the mast was most difficult because the mast clamp is between the elements of the 40m loop element and there is a lot going on in a small space.

    All strapped in

    Here is a good shot of the entire setup.

    On Top
     There is no way I could have gotten this done without the help of my son Hudson.

    Ariel and Hudson
    73 for now

    Saturday, August 24, 2013

    Canadians at the Vattenfall World Triathlon Stockholm

    Hej Hej!

    The unusual record number of very fit folk at the hotel was a give away that something was happening in Stockholm this weekend, the question "what could it be"?

    Bib 11, Kirsten Sweetland
    Well,... the Vattenfall World Triathlon Stockholm  was this weekend and the women elite race was today. I was happy to see two Red Mapleleafs in the swim-bike-runing, makes you proud in a Canadian kinda way.

    Bib32, Ellen Pennock
    More photos are at my PBase albums. I'm happy I stayed in town, the afternoon pasted quickly and it was fun to see some of Canada's Elite.

    Way to go girls!


    Friday, May 24, 2013

    The New QTH

    Hi  OM

    Well, this has been a long time coming but we have moved from the cramped noisy city to a mode spacious and quiet QTH.

    The station has been setup,  a quick run down of the shack is
    • Palstar AT1500CV Tuner
    • Kenwood SM-230 Station Monitor
    • Kenwood TL-922A Linear
    • Yaesu FT2000D
    • iCOM 756 Pro-III
    • Kenwood TS-850S
    • iCOM 7000 (for 2m)

    The Radio Shack

    The QTH is 33 rural acres south of Ottawa and the power line noise of the old QTH is no longer a problem.

    Country QTH

    The lot is 450ft wide by 1km deep, so there is plenty of space to imagine and work with.

    I am really looking forward to getting back on the air.


    Sunday, January 27, 2013

    2013 - Silent Lake

    We are here gain.

    The link above, will take you to my post from last year's winter Yurt field operation.



    Thursday, November 8, 2012

    Can you hear me now!? Kenwood TL-922A

    For some time I have had my eye on a few linears, and when this one showed up on eBay recently I could not resist. The Kenwood TL-922A unit was for sale and a weekend trip from Ottawa to Manchester New Hampshire made a safe and enjoyable way to get the unit home.

    In the picture below, the amp is shown along side of my father's (VE1JNA - SK) Kenwood TS-850SAT, and these do make a nice pair.

    Kenwood TS-850SAT and TL-922A
    The TL-922A is a heavy brute coming in at 31kg. Flipping this beast over, when working on it will leave marks on your desk if you are not careful!

    The HV supply has two modes which change the plate voltage from 2.2kV to 3.1kV for CW and SSB modes. In SSB mode this amp is specified to generate 1kW out for approximately 80W in. (This is what the curves at the back of the service manual say!)

    Call me old fashioned, but if you are like me, then you too believe radios must have plenty of knobs and switches to be interesting. I should add that the metering on the TL-922A also meets my expectations too.  I know analogue meters miss the peaks but there is a satisfaction in seeing the physical needle move as you tune up the amp.

    TL-922A Metering

    Many folks have commented on the physical build quality of this design, and I will add my comments to the pile-up. I did not confirm when this unit was built, but being of the late 1970's, I can say this 30 year old unit will be here for many years to come because it does not show its age. I was very lucky because the previous owners, and I do not know how many there were, have taken good care of this amp.


    Kenwood TL-922A

    I have picked over much of this amp from outside and in, and in terms of modifications, there are only a few.
    1. The Tubes are a pair of 3-500Z's from the good folks at RF Parts.
    2. The suppressors are the original Kenwood items and have not been changed out.
    3. The 10M band addition was done as described here
    4. The HV caps have been replaced with Cornell-Dubilier 210uF 450VDC
    5. The SS-100 Universal Soft-Start from Harbach was installed
    Thee are two signs of undesired operation, but first I must say that the unit was very clean otherwise. The 1000pf 15kV plate cap, in the center of the image below, has a odd "scar". You can see it in the picture below. The discoloration is highly localised on the edge of the cap, and is "baked on" in that it does not rub off. I am unsure what would have caused this.

    Burnt Plate Cap?
    The bandswitch was ruined and I had half expected this to be the case. I was able to get a new switch from Multi Tech Industries . Although it took me a bit longer to get it in, it was a easy job none the less. You do have to be careful to make sure every thing gets connected back to where it started.

    Installed Multi Tech Band switch
    Interestingly, the amp was able to run on all but 20m. A close inspection of the 20m input filtering led me to a pair of mica caps that had been pushed against each other. This caused their leads to cross and touch, shorting out the inductor. Simply fixing this, made the input SWR drop from over 100:1 to 1:1 and 20m was now in business too.

    Shorted input filter for 20m

    As an example, operating on 40m, the setup below shows 55W in and 650W out. The plate and grid currents are 450mA and 150mA.

    55W in and 650W out

    Having only had the amp for a few weeks, I know this is going to be a good addition to the shack. If you are in the market for a this piece of Kenwood history, I hope you are able to find an Amp as well cared for as I was able to.

    MHz       1.8    3.5     7     14     21    28
    Band      160m   80m    40m    20m    15m   10m

    Plate     3.5    7      7      14     21    >21   
    Load      0      1.8    2.2    4      4.2   4.8
    Ip (dip)  Yes    Yes    Yes    Yes    Yes   Yes
    Ip        480    500    500    500    500   350   (mA)
    Ig        200    150    180    175    150   150   (mA)

    HV       1900V  1900V  1900V  1900V  1900V  1900V  at load

    Pout      550    600    700    800    625    435   (W)
    Pin        65     55     75     70     55     40   (W)
    SWRin    1.5:1   1:1   1.3:1   1:1   1.3:1   2:1