Marconi's model of the I-10K to specs

[Marconi]

Well Bob, this wasn't easy. Out of convenience I removed all the tapered sections I originally added to the model. Instead I made it one element at 257.375" x .75" diameter for 27.205 mhz, just like I did the SP 500. The top hat is there, but is not included in the overall length noted here.

Modeling the I-10K is far more difficult, even at this stage in my learning, than the Sigma4 was months ago. The fact that it uses an insulator forced me to model the trombone tuner as well. I did the model with the insulator and the radiator hanging out in free space, but the pattern was terrible. I'm not sure I understand why this is. I had to do it anyway, in order to get the feed point in the right position as it sits on the antenna.

I still have some work to do on the tuner just to try and get it as near perfect as I can. I won't bother with trying to curve the ends, but I need to get the T1 end in its proper perspective. Right now it's positioned straight up and down in the direction of the radiator, and it should be on a small angle. The ends of the tuner do not show the correct end dimensions as a result either. So, consider this.

I did see the match improve, albeit still isn't perfect with an SWR at 3.36:1, but it improved significantly when adding the TB tuner. However, with way too much obvious current flowing on the mast, the antenna is still not showing the gain I would expect. It still needs work.

I was able to split the source to get the feed point very close to where it is on the antenna, excepting for the little pigtail wire that goes down to the SO 239.

The free space model is very similar to the one that Sirio shows us in the Gain Master documents, and the Average gain is fairly good as noted on the FS image.

Believe it or not this model also shows a even weaker horizontal pattern. I check my previous models for my 5/8 waves and there is nothing like this in their patterns.

I'll be working on this trying to improve the gain and AG.

View attachment I-10K to specs.pdf

 

[bob85]

is it an illusion eddie or are the radials short relative to the vertical and trombone?

 

[Marconi]

Marconi's model of the I-10K to specs modified.

Well Bob, I finished with my Sunday School project sooner than expected, so I got back to the I-10K model. I haven't quite got there yet, but my idea is showing some promise. Maybe I'll have some proof if I can tweak the model and get it a little closer.

The big problem may be that the antenna is asymmetrical in the ground plane and the matcher, so maybe Eznec will never produce a match on the money, but it's far closer now than with any of my other 5/8 wave models, including my model of the Cebik 5/8 where I duplicated his matching results perfectly.

In measuring the antenna I found other miscue's in the dimensions, which I ignored in the model and I made a couple that I have not fixed yet...at the ends of T1 and T2. I also didn't try to set the radials askew, off-center of the antenna as they really are, so that is at work also. I used my own tuning dimensions for T1,T2, and V7, at 27.205 mhz. As I said earlier, I also didn't taper the radiator, and that will also make some difference.

In the attached PDF file I included my model of Cebik's 5/8 for comparison of the matching results only, so you can see how the match differs from a similar 5/8 wave antenna with no matcher. I think this is just like I said in my email, and I expect it to get even better when I have a chance to fine tune and fix the errors I see.

View attachment I-10K to specs modified vs. Cebik's .58 r 99'' R 255''.pdf

 

[Marconi]

is it an illusion eddie or are the radials short relative to the vertical and trombone?

You have sharper eyes than I do Bob. I discovered this today in my re fix of the model. This can happen when working wires that do not fall directly on the X,Y, or Z coordinates.

I talked about it in my email.

Here are the wires:

View attachment I-10K Wires.pdf

 

[Marconi]

Bob, I was wrong in the post above. I have chased my tail over this issue several times and I find the model I posted is still off just like you describe...the radials are short. This is what I get for using taper I think or else I got started wrong in my idea for radials. I did not use the auto radial feature and I should have. It would make the model much more simple, even if it would not be to specs. I've already done the radiator, so what difference will it make at this point. I guess I was more tired than I thought.

I'll try and fix this and get back on track.

 

[bob85]

i just read your email eddie,
i don't understand the wires charts but looking at the model it looked out of proportion and thought that could be the reason you see significant mast currents below the short radials,

good luck in getting the model straightened out.

 

[walterb]

HGP-500

After installing the new HGP-500 antenna at my QTH last month and doing some primary testing against my reference A99 at 38' to the bottom of the A99
The new HGP-500 has stopped my desire to compare any more base antennas! These are observations that jump out at me so far. The A99 seems to have more gain or receive an sometime that works for ya and sometimes it works against ya, but its different, with less gain the HGP-500 is quieter and I hear weak signals better to my ear. Last week there was a bad wind storm at my QTH an I was our of town, the HGP-500 at 30' to the bottom made it through it with only slight damage to guide lines which I had to retighten the lines, (2) HAM wire antennas did not weather as well. That answered my question if my antenna would hold up under high winds. All this stuff is seat of the pants observations but have been doing this stuff longer than I can remember. I now know why the HGP-500 was so revered in its day by CBer back in the 70s. Its a great antenna to listen to, and has stoped my quest for a better base CB antenna!...........Oldtimer

 

[Marconi]

Walterb thanks for the report. I won't be testing a real SP 500, but I started modeling one at: http://www.worldwidedx.com/cb-antennas/123067-marconis-penetrator-500-eznec-model.html

I told Bob that I was finished tweaking my SP 500, unless I got some real specs. Now after doing this I-10K above, which is not finished, I may try the matching network on the HyGain also, if I can get some good measurements that I can confirm with some measurements I already have.

Thus far about the best info I've gotten are some general ideas about the overall length being 22' feet...from the very bottom to the very tip, but I don't know if the source for this info tested it somehow or just said it...because it was in his manual. I'm not sure about the radial lengths either.

The manual shows one radial at 105" from the inside of the mounting bracket to the tip, but inside of the mast side of this bracket is off center, and the other three radials are not described. IMO, all three could have different lengths since this bracket is not centered to the radiator with this measurement. The radial bracket is centered and it will easily allow the radials to be symmetrical around the radiator, so I don't know why HyGain didn't described the install better using that bracket. They could have meant to do that, and that would make sense, keeping everything balanced and symmetrical. For me, that would be good, because I believe symmetry is important.

How did you do your radials? Did you record any dimensions, like the overall length, note the best SWR frequency as installed, and did you check and record the SWR or analyzer bandwidths for less than 2.0:1 using an analyzer or and in line meter? I could use such information against the details in my model.

Any info you have and can share would be appreciated. I had to guess on some of my SP 500 dimensions, and I don't have a matcher included yet. Trying that will be next.

Marconi

 

[walterb]

HGP-500

Marconi,
I built the antenna per the instruction manual which called for 8'9" per radial the only change I made that was different was the overall height was listed at
19' that would be for 10 meters of course. I set it to 22' then I dropped it to where the SWR using my MFJ-259A was close to 50 ohms at CH20 27.205 1.3 SWR and CH 1 & 40 were 1.5. Think the overall height ended up around 21' 6 or so. The 8'9" radials butt up against each other the way the radial plate is. Happy with the antennas performance. Am using 100' on RG213U to feed this antenna at 30' TTB. Hope this is of some value to ya. The antenna WORKS an the receive SOUNDS RIGHT to my ear........Oldtimer

 

[Marconi]

Marconi,
I built the antenna per the instruction manual which called for 8'9" per radial the only change I made that was different was the overall height was listed at
19' that would be for 10 meters of course. I set it to 22' then I dropped it to where the SWR using my MFJ-259A was close to 50 ohms at CH20 27.205 1.3 SWR and CH 1 & 40 were 1.5. Think the overall height ended up around 21' 6 or so. The 8'9" radials butt up against each other the way the radial plate is. Happy with the antennas performance. Am using 100' on RG213U to feed this antenna at 30' TTB. Hope this is of some value to ya. The antenna WORKS an the receive SOUNDS RIGHT to my ear........Oldtimer

Thanks Walter.

I made too much of the radial issue here. All one has to do is just set the radials at 105" and install them in the hub, and they will be symmetrical, just like you describe. Forget the picture. I just didn't see that until now.

If you can, how high was the antenna when checked with the 259a, and do you remember what the reactance was at 27.205? And, did it seem to change on raising? If I can model the matcher, such info could at least give me some numbers to consider for my model's match.

From your numbers, the antenna looks to be narrow banded. Do you know what the <2.0:1 bandwidth is on your 259a? That'll help me too.

I think you'll find that at 10 meters the SP 500 will be longer than 19' overall, from very bottom to very top, when set for 10 meters. There is just not that much difference between 10 and 11 meters.

Here is the same manual from a recently purchased antenna and this length noted...has been changed to 22' feet. I think 19' was just a mistake, or a correct measurement that was identified incorrectly in the picture.

http://i43.photobucket.com/albums/e399/nordland/SP5002.jpg

Eastside posted the following in a thread at post #196, where there was a discussion on this very subject: http://www.worldwidedx.com/cb-antennas/108500-bbt-delivered-hy-gain-penetrator-500-today-20.html

 

[walterb]

HGP-500

Marconi,
When I had the antenna set at 22' I think low SWR was was around 26.400+ as I remember. The antenna was 16' off the ground and I was using a 3' jumper! I don't remember what the reactance was, sorry. 2 to 1 swr would be about 80 channels I would think, nothing like a A99 that I use, but I like listening to this antenna for some reason a lot, I use it with a Connex CX33 Base radio and the sound of a strong station sounds like there standing in front of you and you can touch them! With my A99 the same sound sounds like the sound is pushed
toward you, not relaxed sounding, for what that worth hmm. Have electronic switching so can compare up to 4 antenna in a second an that helps in comparisons. Time will tell when other posts coming in using this antenna an we can compare the feedback, two ...........Oldtimer

 

[Marconi]

Marconi,
When I had the antenna set at 22' I think low SWR was was around 26.400+ as I remember. The antenna was 16' off the ground and I was using a 3' jumper! I don't remember what the reactance was, sorry. 2 to 1 swr would be about 80 channels I would think, nothing like a A99 that I use, but I like listening to this antenna for some reason a lot, I use it with a Connex CX33 Base radio and the sound of a strong station sounds like there standing in front of you and you can touch them! With my A99 the same sound sounds like the sound is pushed
toward you, not relaxed sounding, for what that worth hmm. Have electronic switching so can compare up to 4 antenna in a second an that helps in comparisons. Time will tell when other posts coming in using this antenna an we can compare the feedback, two ...........Oldtimer

Thanks for the numbers Walter. I have heard another owner say the antenna appeared to be low in frequency when set at 22' too, but I don't know the height and that may make some difference. How about using the 259a with the feed line? How does it look in the air, bandwidth and R, X, SWR, at 27.205?

Here is my modified SP 500 with the latests matcher, but it is not right yet:

View attachment SP 500 matcher.pdf