Homer's Qv4k

[HomerBB]

I have been redoing the Qv4k.
I have it in a temporary testing location, and even that will be changing. Due to work schedule and rain I have o quit for today. First time up it is a 2.4:1 on 40 and a 1.8:1 on 1. It is currently tuned below ch1 it seems. I made QSO with WR54 in Colorado. I'll keep you posted with photos.

 

[GnG8d]

Is that what you were on today? I heard you on 38lsb just as I was getting off the highway headed into Lowes for some concrete. By the time I got parked eveybody faded out.

 

[BOOTY MONSTER]

looks nice homer . got any close pics ?
i see you used 2 different basket supports/insulators , what did you use to make them . im trying to find a old used kids round snowboard or pool/sandbox with a thick bottom , or the top off a 55 gallon plastic drum or something like that ..... something that will last a few years in the sun and cold .

 

[HomerBB]

Is that what you were on today? I heard you on 38lsb just as I was getting off the highway headed into Lowes for some concrete. By the time I got parked eveybody faded out.

I called about 3 - 4 times around 1:00 PM on this. Earlier I was on what you see in the background. Either the 4 element Yagi, or that homebrew mobile antenna above the Yagi.

I heard some calls I couldn't pull out of the QRM, even some calling for Homer.

 

[HomerBB]

looks nice homer . got any close pics ?
i see you used 2 different basket supports/insulators , what did you use to make them . im trying to find a old used kids round snowboard or pool/sandbox with a thick bottom , or the top off a 55 gallon plastic drum or something like that ..... something that will last a few years in the sun and cold .

I'll get those photos online by tomorrow AM. I used empty wire/rope spools available free from your local Home Improvement retailer. TYhe upper one uses PVC tubing as the arms.

 

[Marconi]

I have been redoing the Qv4k.
I have it in a temporary testing location, and even that will be changing. Due to work schedule and rain I have o quit for today. First time up it is a 2.4:1 on 40 and a 1.8:1 on 1. It is currently tuned below ch1 it seems. I made QSO with WR54 in Colorado. I'll keep you posted with photos.

Looks great Homer, good luck in your tuning efforts.

Since you are currently working with a bit of SWR, and if you recall my earlier request in this regard, try and take notice if the higher SWR seems to ill-affect the responses compared with it shows a better tune. I plan on tuning my S4 with a longer radiator and your tuning moves will help me move...as my adding length is sure to make resonance go lower.

I would really be interested in the gamma tuning (general direction) you use to get the tune up into CB. Also what overall lengths, radiator and radials, are you set before you re-tune.

 

[HomerBB]

Marconi, right now everything is too long for the posted specs. It's easier to remove length than add, so the vertical is 27' 9" while the 4 radials are each 108". The gamma I'll likely redo as I went with the one I'd used before. It is a 1/4" aluminum rod 36" long all the way into the gamma sleeve and the strap is set at 33" up from the feedpoint on the vertical. Lengthening the gamma runs the SWR higher. I want to use a 3/8 rod in the gamma. I seem to hearing and talking well with it, The feedpoint of the antenna is 15' off the ground, and around 2' above that roof edge. The tip of the thing is still about 42' up. No doubt this thing is tall!

I want to move the antenna away from the house out back so it's easier to eaise and lower while tuning. I am not sure which way I'll have to go with it all, but the sense of it is I'll need to move the strap around, too, to get a tune.

I was in error about the SWR. It is a tiny bit better with 2.2:1 on ch40 and 1.6:1 on ch1

 

[BOOTY MONSTER]

i'm gonna use 27 inches for the arm height for my gamma when i finally get my mess together per shockwaves suggestion . but im also using larger gamma materials because i already had the 3/8 rod so i only needed the 1/2 inch i.d. tubing

Making a gamma with a 36 inch 3/8 rod and 10 inch 1/2 tube should have more then enough capacitance and length to match this antenna. The tap point from rod to radiator is typically around 27 inches up from the connector bracket. If you correct the angle of the radials at the base, your radial support disk is an insulator, and your gamma is close to these specs, I'm at a loss as to why you can't match it. You can change element lengths on this antenna by feet, making the antenna completely ineffective but yet the gamma can still be tuned to provide a perfect match in nearly every case.

http://www.worldwidedx.com/cb-antennas/31799-avanti-sigma4-alternative-view-point-27.html

 

[HomerBB]

I looked for, but overlooked this very bit of info on the gamma.
Very useful, so thanks, Booty. I will see if I have a 3/8" rod in stock here in the store before I leave tonight. If so, I'll replace the 1/4" rod with it. The tube is already 1/2" ID.

 

[BOOTY MONSTER]

Crown Bolt 3/8 in. x 36 in. Round Rod Aluminum - 49380 at The Home Depot

 

[HomerBB]

Crown Bolt 3/8 in. x 36 in. Round Rod Aluminum - 49380 at The Home Depot

Yep. My vendor has been a little lame about keeping my stock levels up, so I'll go look for it after break.

 

[Shockwave]

I looked for, but overlooked this very bit of info on the gamma.
Very useful, so thanks, Booty. I will see if I have a 3/8" rod in stock here in the store before I leave tonight. If so, I'll replace the 1/4" rod with it. The tube is already 1/2" ID.

The 1/4 inch rod is the reason your gamma is tuning with the rod all the way inserted into the lower 1/2 inch tube. With 1/4 inch rod and 1/2 inch tube there is too much space between the two conductors to reach the right value of capacitance unless the gamma is made longer. The 3/8 rod and 1/2 inch tube make the length to capacitance ratio more suitable.

 

[HomerBB]

I had a feeling something like that was going on. I picked up a 3/8" rod for it tonight and will get it swapped out as soon as I get the opportunity.

Thanks, SW

 

[BOOTY MONSTER]

if 1/2 inch outside diameter tube rather than 1/2 inch inside diameter is used with the 1/4 inch rod should it work right then . i think that's what bob85 meant when he said the the stock vector gamma used .236 (1/4 inch) rod and .512 (1/2 inch) tube .
btw , what are you using for insulating between the tube and rod on your gamma ?

 

[HomerBB]

Booty, I use a piece of PEX pipe over the rod. The 3/8" ID x 1/2" OD PEX fits just snugly into the aluminum gamma sleeve tube. If you look at the photo closely you notice the rubber cap on the sawhorse. It goes in the upper end of the gamma sleeve and hold the rod in the center and prevents rain from entering the tube at the top.