AstroPlane up and Testing

[Starduster]

Just got my copy of an old Astroplane completed and up for testing. The SWR is lowest at channels 1 -6 (1:1). I had it tuned for channel 20 when it was lower to the ground but now it had changed on me.
I really wanted to copy the Astro beam but thought that this would be a steping stone as some parts are the same. Should have the beam done shortly. Is anyone intersested in the Astrobeam or Astroplane?
My improvements in the design are machanical making it much more robust. I have a basic machine shop in the garage and am having a blast making custom antenna parts.
Electrically the antenna is the same but it has the added ability to tune for your favorite center frequency.
First contact SC from WI barefoot.

 

[NorthStar]

Looks like you have a good start

 

[ron103067]

Nice job there wish I had a setup to make an antenna like that

 

[Marconi]

Just got my copy of an old Astroplane completed and up for testing. The SWR is lowest at channels 1 -6 (1:1). I had it tuned for channel 20 when it was lower to the ground but now it had changed on me.
I really wanted to copy the Astro beam but thought that this would be a steping stone as some parts are the same. Should have the beam done shortly. Is anyone interested in the Astrobeam or Astroplane?
My improvements in the design are machanical making it much more robust. I have a basic machine shop in the garage and am having a blast making custom antenna parts.
Electrically the antenna is the same but it has the added ability to tune for your favorite center frequency.
First contact SC from WI barefoot.

Hello Starduster, for some time I have touted the Starduster and the AstroPlane. I have claimed that if you get the tips of these two up as high as any other of the longer antennas you will see similar or better local signals when compared side by side. Last summer I compared RX signals and made bandwidth plots while tuning of several vertical CB antennas that I have. I posted all of my results in my profile albums. See: http://www.worldwidedx.com/members/marconi.html

I think you suggest modifying your Top One to look like the driven element on the AstroBeam. I suppose that means to make the top element a straight full 1/4 wave element, right? Here is one I modified last summer when I was comparing it to my Sigma IV.



IMO, seeing a drop in frequency when you raise an antenna may well happen in some cases, but I see the same thing, for sure, when changing the length of the feed line. IMO, this shifts the apparent resonance and does so when my tune is not perfectly resonant at the same tuned frequency of choice. I think this has to do with the antenna being reactive, showing a standing wave on the feed line. Example: in your comments, if you tuned your AP with a jumper and then when you raised the antenna you used a longer feed line, then you might see such a response---and this is due to feed line transformation IMO. If this is not the case in your situation, then raising probably caused the drop in frequency.

Good luck and keep us posted on your results.

 

[jazzsinger]

Just got my copy of an old Astroplane completed and up for testing. The SWR is lowest at channels 1 -6 (1:1). I had it tuned for channel 20 when it was lower to the ground but now it had changed on me.

An antenna should be tuned in its final mounting location,although not always practical,the simple way around it is to take it up and down,tuning it while down and measuring it whilst back in location,if you measure it whilst its down the ground and anything around it will interact with it.

It may be a bit of extra work,but if you want it as fine tuned as possible quite often its the only way.

 

[Starduster]

Hello Starduster, for some time I have touted the Starduster and the AstroPlane. I have claimed that if you get the tips of these two up as high as any other of the longer antennas you will see similar or better local signals when compared side by side. Last summer I compared RX signals and made bandwidth plots while tuning of several vertical CB antennas that I have. I posted all of my results in my profile albums. See: http://www.worldwidedx.com/members/marconi.html

I think you suggest modifying your Top One to look like the driven element on the AstroBeam. I suppose that means to make the top element a straight full 1/4 wave element, right? Here is one I modified last summer when I was comparing it to my Sigma IV.

View attachment 2603

IMO, seeing a drop in frequency when you raise an antenna may well happen in some cases, but I see the same thing, for sure, when changing the length of the feed line. IMO, this shifts the apparent resonance and does so when my tune is not perfectly resonant at the same tuned frequency of choice. I think this has to do with the antenna being reactive, showing a standing wave on the feed line. Example: in your comments, if you tuned your AP with a jumper and then when you raised the antenna you used a longer feed line, then you might see such a response---and this is due to feed line transformation IMO. If this is not the case in your situation, then raising probably caused the drop in frequency.

Good luck and keep us posted on your results.

The slight change in SWR don't concern me in the least, still have a less than 1.3:1 across the band. As stated by Jazzsinger the antenna should be tuned in its final position. I had it about 20' off of the ground to get the feel for tuning it and to see what element length change made what difference. The Astroplane is kind of sensitive to height as I understand. My intention is to leave the top hat alone on this antenna and to also to build an Astrobeam.
I had an Astrobeam once and liked the front to back rejection. I am not quite sure if I can find the 35 ohm coax for the matching system or if it is really needed. I know some guys had a better match without it. Should have the beam ready soon, most of the parts are made.
My hang up will be getting the tower ready. I found a nice 45’ Rohm 25 for free but I had to take it down. Now I would like to make a tilt down out of it so tuning can be made more user friendly. I am planning to play with other antennas also. The station really starts with the antenna system.
I am kind of an old guy and was into CB heavy in the 70’s and really like playing with antennas.
One of my problems is that there is very few people that are involved around here locally anymore. It makes radio checks kind of hard.
Back in the day I ran a Starduster and really did a good job with it. Now I think ideally a 5/8 wave maybe the way. The duster was up about 100’ or so. In the end I also think height is really the key factor for a good omni antenna set up
Thanks for the reply; it’s nice to talk to someone with similar interest.

 

[mackmobile43]

The slight change in SWR don't concern me in the least, still have a less than 1.3:1 across the band. As stated by Jazzsinger the antenna should be tuned in its final position. I had it about 20' off of the ground to get the feel for tuning it and to see what element length change made what difference. The Astroplane is kind of sensitive to height as I understand. My intention is to leave the top hat alone on this antenna and to also to build an Astrobeam.
I had an Astrobeam once and liked the front to back rejection. I am not quite sure if I can find the 35 ohm coax for the matching system or if it is really needed. I know some guys had a better match without it. Should have the beam ready soon, most of the parts are made.
My hang up will be getting the tower ready. I found a nice 45’ Rohm 25 for free but I had to take it down. Now I would like to make a tilt down out of it so tuning can be made more user friendly. I am planning to play with other antennas also. The station really starts with the antenna system.
I am kind of an old guy and was into CB heavy in the 70’s and really like playing with antennas.
One of my problems is that there is very few people that are involved around here locally anymore. It makes radio checks kind of hard.
Back in the day I ran a Starduster and really did a good job with it. Now I think ideally a 5/8 wave maybe the way. The duster was up about 100’ or so. In the end I also think height is really the key factor for a good omni antenna set up
Thanks for the reply; it’s nice to talk to someone with similar interest.

You may have to do as I do and use your mobile as a rx station.
Nice work.

 

[Starduster]

You may have to do as I do and use your mobile as a rx station.
Nice work.

That sounds like a plan.

 

[mackmobile43]

Do you have a total cost for your antenna? and some close up pictures for the hoop to mast vertical connections are desirable.

 

[Marconi]

Starduster, if I said I was concerned about the SWR you saw, then I misspoke.

 

[Wire Weasel]

Hey Starduster & Marconi. Good luck with the AstroPlane project! Speaking of the retros, I still have a NOS A/S Antenna Specialist Starduster in the box if anyone is interested. Make a reasonable offer.

Good luck!

 

[Starduster]

Do you have a total cost for your antenna? and some close up pictures for the hoop to mast vertical connections are desirable.

This is a photo of the mast attachment. Its kind of hard to get a good one now that the antenna is up but will work on it latter today and see if I can get some better ones.

Reply to Marconi;
Starduster, if I said I was concerned about the SWR you saw, then I misspoke.
No misunderstanding what so ever.

 

[mackmobile43]

Thanks Starduster.

 

[bob85]

looking good starduster, another enigmatic avanti design, the astroplane patent is interesting reading,
its good to see somebody experimenting

 

[jazzsinger]

I am not quite sure if I can find the 35 ohm coax for the matching system or if it is really needed. I know some guys had a better match without it.

i doubt you would really need 35 ohm coax,but if you were desperate for the perfect match you could always parallel two 75 ohm coax runs,that would give a 37.5 ohm matching section which is as near as dammit and 75 ohm coax is commonly available.