HyGain SPT-500 Penetrator

[titan2a]

Just built this antenna and raised it to 25 feet

Tuned to a near flat SWR.

Four watt radio now moves the meter to the 2 watt marker
Another 4 watt radio moves the meter to the 2 watt marker..
The third 4 watt radio moves the meter to the 2 watt marker..

Change out coax and get the same results.
Attach the Coax to a 16 watt dummy load, radio now gets the full 4 watts registering on the meter 

Attach the Coax to an Antron 99, the meter moves to the 4 watt marker.

Reattach the coax to the HyGain antenna and the meter only moves to the 2 watt marker.

Ask for a radio check, everything is great!
Ask for a radio check in the distance.. (35 miles away) and get a good report.

So, the antenna is working, but the low meter reading is worrying me.

Help me understand what is happening..

I do not have an antenna analyzer.

[Sandbagger]

Feb 24, 2014 21:29:18 GMT -5 titan2a said:

Just built this antenna and raised it to 25 feet

Tuned to a near flat SWR.

Four watt radio now moves the meter to the 2 watt marker
Another 4 watt radio moves the meter to the 2 watt marker..
The third 4 watt radio moves the meter to the 2 watt marker..

Change out coax and get the same results.
Attach the Coax to a 16 watt dummy load, radio now gets the full 4 watts registering on the meter 

Attach the Coax to an Antron 99, the meter moves to the 4 watt marker.

Reattach the coax to the HyGain antenna and the meter only moves to the 2 watt marker.

Ask for a radio check, everything is great!
Ask for a radio check in the distance.. (35 miles away) and get a good report.

So, the antenna is working, but the low meter reading meter is worrying me.

Help me understand what is happening..

I do not have an antenna analyzer.

What is the antenna's SWR? Most (especially cheaper) wattmeters are very prone to differences in SWR, which can affect what they display for power. Usually though, if the SWR is fairly low and the impedance is close to 50 ohms, the meter should read close to it's calibrated setting (most are calibrated into a purely resistive 50 ohm dummy load).

[titan2a]

On the new antenna, with a four watt carrier, calibrated dead on the calibration line, the SWR registers less than 1.1 on Channel 1 and greater than 1.1 (Not quite 1.125) on Channel 40.

Getting great reports on all radio checks.

The Antron reads about 1.2 on channel one and 1.25  on channel 40..    Dips a little on channel 19 through 25, but like I said, the meter shows 4 full watts on channel 1 and almost four on channel 40

HyGain sent a matching rod that was configured as a mirror image of the correct part.

They are sending me a new one which will be here in a few days, but I was still able to use the first one that came with the antenna (The SWR's are flat).
Would seem like the antenna would not transmit and the SWR's would be through the roof if it were set up wrong.

 

[Sandbagger]

Feb 24, 2014 22:56:19 GMT -5 titan2a said:

On the new antenna, with a four watt carrier, calibrated dead on the calibration line, the SWR registers less than 1.1 on Channel 1 and greater than 1.1 (Not quite 1.125) on Channel 40.

Getting great reports on all radio checks.

The Antron reads about 1.2 on channel one and 1.25  on channel 40..    Dips a little on channel 19 through 25, but like I said, the meter shows 4 full watts on channel 1 and almost four on channel 40

HyGain sent a matching rod that was configured as a mirror image of the correct part.

They are sending me a new one which will be here in a few days, but I was still able to use the first one that came with the antenna (The SWR's are flat).
Would seem like the antenna would not transmit and the SWR's would be through the roof if it were set up wrong.

 

Well, it would seem that your SWR is ok, and I'd agree that if something were not right, that it wouldn't work, and the SWR would be high. But it's not always that easy. SWR is only one part of the total picture. Impedance is made up of capacitive, inductive and resistive components which can add up in different ways. Ideally we want the capacitive and inductive components to cancel each other and leave us with a simple resistive load. But it's not always achievable. If you can find someone who has an MFJ antenna analyzer, that would give a better picture of what's going on. I've had antennas in the past that had great SWR, but the feedpoint impedance was 40 Ohms or 70 Ohms or similar. Different setting of the gamma match would allow both the SWR to come in AND have the impedance come closer to 50 Ohms.

[cbrown]

I agree; see if you can find someone with an antenna analyzer.

[titan2a]

Something so simple and yet so expensive.
I am petitioning all of my friends in the hope of finding an antenna analyzer.
For me it would be a one time use (in the present) and maybe used five more times in my lifetime.

Perhaps I will just buy one on ebay, then sell it the next week...

Sad to have so many friends with so much equipment and so few essential tools.

I am using my cheapest radio to test the waters to see if this antenna will have any ill effect.
Hating to use/lose something of value.

THank you for your knowlegeable input and for providing a frame of reference before planing a course of action that may ulitmately affect several pieces of (in my mind) irreplaceable equipment.
 
On a side note: We all have our favorite radios.
One that I am most attached to: My Uniden Grant XL (although physically replaceable) gets the best audio reports of any radio I have ever owned.

It has full modulation (no clipping ever); it has full swing (Dead Keys a gentle 2 watts and swings smoothly to four watts) and has the loudest, clearest broadcast audio of any radio with-in my local area.
In fact there is a big difference when compared to any of my other radios.

The locals have invested a lot more money than I ever will into their hobby and yet, there is an instant response from the local CB crowd when I switch to the Uniden.
Something sweet happened in its set-up.

The old gentleman I purchased this radio from was highly respected (though not always loved) and died shortly after I purchased it.
He swore by 4 watts and full modulation..  
He spent his life testing and working on legally getting the most out of his equipment. 
Almost everyone that dealt with him called him a grumpy old man (not the beloved Grumpy of this forum) and disliked it when he would roll their equipment back to the legal 4 watt limit.
I miss him and wish I had visited him more often.

If the problem does not clear up with the HyGain SPT-500, I am tempted to set up the old Antron 99 on the other side of the house and use it just for the Uniden.

Thank you again for your responses..







 

[Sandbagger]

Feb 25, 2014 17:24:49 GMT -5 titan2a said:

Something so simple and yet so expensive.
I am petitioning all of my friends in the hope of finding an antenna analyzer.
For me it would be a one time use (in the present) and maybe used five more times in my lifetime.

Perhaps I will just buy one on ebay, then sell it the next week...

Sad to have so many friends with so much equipment and so few essential tools.

I am using my cheapest radio to test the waters to see if this antenna will have any ill effect.
Hating to use/lose something of value.

THank you for your knowlegeable input and for providing a frame of reference before planing a course of action that may ulitmately affect several pieces of (in my mind) irreplaceable equipment.
 
On a side note: We all have our favorite radios.
One that I am most attached to: My Uniden Grant XL (although physically replaceable) gets the best audio reports of any radio I have ever owned.

It has full modulation (no clipping ever); it has full swing (Dead Keys a gentle 2 watts and swings smoothly to four watts) and has the loudest, clearest broadcast audio of any radio with-in my local area.
In fact there is a big difference when compared to any of my other radios.

The locals have invested a lot more money than I ever will into their hobby and yet, there is an instant response from the local CB crowd when I switch to the Uniden.
Something sweet happened in its set-up.

The old gentleman I purchased this radio from was highly respected (though not always loved) and died shortly after I purchased it.
He swore by 4 watts and full modulation..  
He spent his life testing and working on legally getting the most out of his equipment. 
Almost everyone that dealt with him called him a grumpy old man (not the beloved Grumpy of this forum) and disliked it when he would roll their equipment back to the legal 4 watt limit.
I miss him and wish I had visited him more often.

If the problem does not clear up with the HyGain SPT-500, I am tempted to set up the old Antron 99 on the other side of the house and use it just for the Uniden.

Thank you again for your responses..

Don't worry too much about not having an antenna analyzer. They didn't exist back in the 60's and 70's yet somehow we all managed to get by.

Tube radios by nature of their adjustable pi network, can tolerate a much wider impedance variation without a noticeable degradation in performance. Most solid state radios can also tolerate a reasonable deviation from the nominal 50 Ohm specification. As long as the SWR is low, you will probably not have to worry about equipment damage. In fact, the notion of "blowing" finals is a bit of an exaggeration. Yes, it can and does happen when parts are stressed. But the idea that if you accidentally key the mic without a coax cable attached, automatically frying the final transistor just doesn't normally happen. When I was a teenager, they had a display of CB radios at the local K-Mart (Spark-O-Matic). They were hooked up to a power supply (presumably so that people could see them powered). They had the mics attached too, but NO ANTENNA! Needless to say, my mischievous nature got the best of me, and I stuck a rubber band around the PTT switch on the mic connected to one of the radios, locking it in transmit mode, and walked away. I came back to check on it 3 days later and the radio was still transmitting (At least according to the RF meter on the radio)! I don't know what was more surprising, that the radio was still working, or that nobody had bothered to check the radio display.

So the moral of that story, don't sweat it. Find the MFJ if you can, but don't be afraid to use it in the meantime.

[doctor]

I just saw an ad on this antenna, and on the last line it says: ILLEGAL FOR CB/11 METERS.
I could not believe it, so looked up another ad on it same thing, who are they kidding.
DOCTOR/795


SPT-500 is specifically designed to accept AM-FM-SSB-DSB signals with low loss. Handles 1.5 killowatts. This antenna is illegal for 11 Meters use.

[cbrown]

During the 1990s they made a rule where 11 meter antennas had to meet certain specifications.

In short, if a company or individual wanted to market an omni-directional CB antenna, the antenna had to be physically tested in a defined test situation where the antenna is intentionally brought in contact with an equivalent of a standard residential distribution primary line, and withstand that contact (with coax and mast connected) with less than 5 mA current flow.

[doctor]

Interesting cbrown, I didn't realize that..thanks for the info.
DOCTOR/795