Dulplexer question

Max · Post by **Max** » Sat Oct 25, 2014 9:37 am

I've been told there are no wrong questions.
Since I have very limited knowledge when it comes to duplexers I thought I would ask for some ones opinion.
If I had a Moto XPR 8300 UHF repeater with a NCG Comet CA-712EFC antenna running 60' of LMR400 and looking at 2 duplexers on ebay,which of the 2 would be the better choice ?

1-eBay item number:231369049764
2-eBay item number:271643252812

Thanks
Max

Will · Post by **Will** » Sat Oct 25, 2014 11:12 am

First of all not many use LMR400 type cable in repeater applications due to intermod and noise problems.

I like the second ebay number ResLock duplexer.

And I do NOT recommend the Comet antenna as there are much better antennas that have real copper elements, not a 18 gauge steel wire with piss poor copper plating.

Post by **escomm** » Sat Oct 25, 2014 11:47 am

Here is a link that will expand your knowledge of duplexers: http://www.repeater-builder.com/antenna ... exers.html

RFguy · Post by **RFguy** » Sat Oct 25, 2014 4:39 pm

What are the RX and TX frequencies? Some duplexers do better at wider or narrower spreads.

As for LMR cable on a duplexer, we have lots in service without a problem. Where problems do arise is where there are multiple TX frequencies combined on the same cable, or nearby. You would want to replace LMR cable more often than you would hardline (such as Heliax LDF4)

Max · Post by **Max** » Sat Oct 25, 2014 5:12 pm

Right now we are using 463.XXXX - 468.XXXX MHz.
I have 2 of the cheap $99 celwave 6 cavity duplexer you can get from China on ebay and had them both tuned to 2 different pairs of frequencies(UHF) with a 5 Mhz spacing ,they both performed terrible.
Again,i'm just now trying to understand and learn the basics on how duplexers work and realize i have a long way to go.I'm guessing the $99 Duplexer are probably a bad first choice.

Max

Will · Post by **Will** » Sat Oct 25, 2014 6:49 pm

Always use the better coax cables for the run to the antenna, Andrew Heliax LDF4 a 1/2 inch semi rigid is the one I and most would recommend.

The 'flatpack' mobile' duplexers are a notch - notch duplexer. They notch out the transmitter frequency on the receiver side, the receiver gets some extra protection because the receive frequency is notched out on the transmitter side. They do not provide any filtering and have more loss and less isolation than the true cavity filter type duplexer like the ResLock you mentioned.

The cables that interconnect the receiver and transmitter to the duplexer should be double shielded with proper connectors.. no adapters.

Bill_G · Post by **Bill_G** » Sun Oct 26, 2014 6:43 am

Max wrote:Right now we are using 463.XXXX - 468.XXXX MHz.
I have 2 of the cheap $99 celwave 6 cavity duplexer you can get from China on ebay and had them both tuned to 2 different pairs of frequencies(UHF) with a 5 Mhz spacing ,they both performed terrible.
Again,i'm just now trying to understand and learn the basics on how duplexers work and realize i have a long way to go.I'm guessing the $99 Duplexer are probably a bad first choice.

Max

Those "mobile" duplexers work okay if they are tuned correctly, AND you have no cable or antenna faults, AND you use them at quiet sites.

As Will explained, they are notch type duplexers - the RX side notches the TX, and the TX side notches the RX. They pass just about everything else. Wonderful if your repeater is the only one at the site (ie: a mall or factory rooftop). Not so wonderful when colocated with other services (ie: broadcaster or community tower).

Even at a quiet site, the cables, connectors, and antenna play a big part in performance. The least little defect can create noise that impairs coverage. Hence the warning about LMR400. All of us have used it, and all of us have been bitten by it. All of us have been bitten by low cost jumper cables and antennas too. You have to use the good stuff to get the best performance. You can get away with low cost materials for a while. Eventually they will cause problems.

But, if the duplexers are tuned wrong, you're broken before you leave the gate. It's not that difficult, but it has to be done right. You will need someone's help.

gtriever · Post by **gtriever** » Mon Oct 27, 2014 4:41 am

I like those old Decibel Duplexers in your first auction link. Built like tanks and easy to tune. I agree with everybody else, good cables/connectors are critical. In fact, we use 1/4" Superflex for our jumpers from Duplexer to Radio, and 1/2" from Duplexer to antenna feedline.

Max · Post by **Max** » Wed Nov 05, 2014 11:32 am

I wanted to follow up with my progress and hopefully get some more advise.
I ended up buying the Sinclair Q3220E http://www.sinclairtechnologies.com/cat ... aspx?id=76 I sent it to Sinclair and had it tune by their service depot to insure proper tuning.
It came back with the test results showing the LP frequency 463.xxxx , insertion loss 0.3 (db) ,HP 468.xxxx, insertion loss 0.45 (db) and both had a return loss of 30 (db) and isolation was 75 (db)
I am using GR400/U for my patch cables between the repeater (XPR-8300 UHF) and the duplexer.I have my Comet CA-712EFC antenna running 75' of LMR400 to the roof of my building ,I know you all have recommended against LMR400,but that's what I had up there before.I also have a NCG Comet CA-F72GF off my balcony (29th floor) running only 15' of LMR 195.The antenna off the balcony is some what restricted as my balcony faces west.
After doing some tests with my duplexer and RPT,I found a significant difference in performance between the antenna's.
The antenna off the balcony preformed a lot better then the antenna on the roof. The antenna on the roof is around 320' with no obstructions and the antenna off the balcony is lower and blocked by my building as well as the antenna on the roof has much more db gain,is it safe to say the problem is the LMR-400 only ?
A member also said the antenna I was using on the roof was a poor antenna,but I would say both antenna's I'm using are close to the same as far as quality.
So I'm just finding hard to believe the coax is making that big of a difference.
PS...i should also include i had to use 2 coax Adapters on the LMR400 75' run because at the time i could not change the antenna connectors to the proper ones.I'm sure this will also be part of the problem.
Thanks

Max

(still learning)

RFguy · Post by **RFguy** » Wed Nov 05, 2014 12:38 pm

Do you have any test equipment? Thru-line watt meter? Antenna sweep equipment?

You need to do some testing to confirm if what power is reaching the antenna and how much (if any) is being reflected.

LMR400 is fine for your application. The issues people talk about is typically related to multiple transmitters on the cable.

Max · Post by **Max** » Wed Nov 05, 2014 1:20 pm

Unfortunately i do not have access to any test equipment and gaining access to my antenna on the roof is limited,meaning i have to make arrangements to get on the roof each time.
Guess i'll have to try and find a friend with some test equipment at this point.
Since you are saying my 75' run of LMR400 is not a issue,that make me even more curious as to what the problem is.

Max

RFguy · Post by **RFguy** » Wed Nov 05, 2014 2:23 pm

Max wrote:Since you are saying my 75' run of LMR400 is not a issue,that make me even more curious as to what the problem is.

Crushed cable, shorted connector, incorrectly installed connector, water ingress to antenna and/or cable, mistuned antenna, impedance mismatch..............

At the very least, you need a thruline watt meter to check forward/reflected power.

Post by **VE3HKB** » Wed Nov 05, 2014 2:30 pm

Ditto - you should at least throw a watt meter on the cable and compare forward and reflected at both ends. Take measurements at the PA output, the duplexer output and antenna.

If you know how each portion should behave, you should be able to confirm what's good and what isn't. Insertion loss of each coax section can be calculated from the length and manufacturer's spec. Connector loss should be less than 0.1dB. If your repeater transmit signal isn't reaching the antenna, then any receive signal from the antenna won't be reaching the repeater.
Normally TX and RX are affected equally in an antenna system (reciprocity), that is, loss/gain one way will be the same the other way (assumes duplexer is performing as tuned).

You would need a service monitor to confirm the operation of the repeater, check for desense, measure noise floor, etc. A spectrum analyzer comes in handy in RF noisy locations to determine what's nearby. After that, the test equipment gets more expensive (sweeping entire antenna system). While a wattmeter can give you an SWR reading, it is only at the one frequency. You can have a bad antenna that tests good. A dummy load tests as a perfect antenna, except for the fact it doesn't radiate.

You can do a basic test for desense. Compare the reception of a weak, but stable signal (a good patient friend is necessary here) with the repeat function enabled and disabled. If your own transmitter wipes out your receiver, that's a big problem.

If you don't know if your repeater is OK, substitute a portable and test with your good and patient friend.

LMR cable itself not a bad product - in many applications it is as good as heliax. But it's not for every application. Also, its construction does require some more attention during connectorization and weatherproofing.

Lastly, an antenna system is only a good as its weakest element. Adapters should be avoided at all costs. The simpler a system is, the easier it is to troubleshoot (and less to fail).

Bill_G · Post by **Bill_G** » Thu Nov 06, 2014 6:47 am

+1

At a minimum, you need a wattmeter on the line.

And you should have the correct connectors on both ends minus adaptors.

But, just for S&G's, let's assume everything is perfect. It could be the gain, or more correctly, the patterns off the two antennas. The way to check that is to swap them.

Max · Post by **Max** » Sun Nov 09, 2014 2:54 pm

I was able to get a friend with a TELEWAVE INC Wattmeter Model 44A stop by and hook it up between my duplexer and my antenna on the roof with the 75' run of LMR-400UF.
It showed 34 watts out and 2.5 watts reflected.
Since i'm use to the old MFJ SWR meters,i don't know how good or bad those measurements are.
Any explanation would be appreciate.

I should include the measurements were done with a digital signal from the XPR 8300.

Thanks
Max

(still learning)

Post by **xmo** » Sun Nov 09, 2014 4:08 pm

Return Loss = 10 log(P1/P2) = 10 log(34/2.5)
RL = 23.6 dB which is close to an SWR of 1.5:1

At UHF a properly configured and operating antenna system will normally be better than that.

Max · Post by **Max** » Sun Nov 09, 2014 6:44 pm

Thanks for your reply.
Are those calculations enough to make a significant difference in performance ?

Max

Bill_G · Post by **Bill_G** » Sun Nov 09, 2014 8:05 pm

At face value 34/2.5 is okay. Not perfect, but usable. On the other hand, it's measured through 75ft of cable. So, we go to Times Microwave for their handy dandy online attenuation calculator. It's says you can expect 2.8db of loss through the total assembly (line and connectors) at 460mhz. And you said previously you have some adapters in line as well. So, let's round that up to 3db for easy math meaning 34 watts gets cut in half to 17 watts at the antenna, AND the 2.5 doubles to 5 watts reflected at the antenna. So yeah, there's a problem. Could be the antenna. Could be the connector. Could be the adapter. You'll have to schedule some roof time to investigate. Hopefully your friend with the wattmeter can accommodate you again.

Max · Post by **Max** » Mon Nov 10, 2014 7:02 am

Thanks for all your replies with my post,it's great to have so many members that take the time to help out.
A few members have suggested using a better coax with less loss,so i think I'm going to change the LMR-400UF to LMR-600UF.
I did look at Andrew Heliax LDF4 but because i have to fish the coax through a bit of a maze,it would be stiff and hard to install so i think LMR-600UF would be easier to use for my application.
So using the LMR-600 with the proper N-connectors and eliminating the 2 adapters should make noticeable difference,i hope.

Max

RFguy · Post by **RFguy** » Mon Nov 10, 2014 8:23 am

Bill_G beat me to it. I often see this happen where a tech doesn't take into account the feed-line loss. I had one where the customer was complaining of poor/no range. The tech checked the antenna and said it was good. Our rule of thumb is we want to less less than 10% reflected. He had 25 out and less than 2 watts back. Less than 10% reflected, so all is good. Right?
Wrong. Cable was just over 200 feet of LMR400. Feed-line loss was 6 dB. His 25-watts was only 6 watts at the antenna. The antenna was open so 100% of the power was reflected. The 6-watts reflected was 1.5 watts at the radio.

Conclusion: Take the feed-line loss into account when sweeping/testing antennas.

Bill_G · Post by **Bill_G** » Mon Nov 10, 2014 8:27 am

Max - Loss isn't the issue. Something is broken. Being 3db down is not a problem. A cable, connector, or antenna failure is. Figure out what caused the failure first. Changing from LMR400 to LMR600 will only gain you one whole db (see the handy dandy Times Microwave calculation page again). That's a lot of effort for a miniscule return. Change the cable only if you know your first run got damaged.

Bill_G · Post by **Bill_G** » Mon Nov 10, 2014 8:31 am

RFguy wrote:Bill_G beat me to it. I often see this happen where a tech doesn't take into account the feed-line loss. I had one where the customer was complaining of poor/no range. The tech checked the antenna and said it was good. Our rule of thumb is we want to less less than 10% reflected. He had 25 out and less than 2 watts back. Less than 10% reflected, so all is good. Right?
Wrong. Cable was just over 200 feet of LMR400. Feed-line loss was 6 dB. His 25-watts was only 6 watts at the antenna. The antenna was open so 100% of the power was reflected. The 6-watts reflected was 1.5 watts at the radio.

Conclusion: Take the feed-line loss into account when sweeping/testing antennas.

+1

Line loss versus the wattmeter, and site noise floor / effective sensitivity, are two basic concepts I try to drill into our new guys.

Post by **VE3HKB** » Mon Nov 10, 2014 3:34 pm

I don't know why the previous calculation is wrong, but it is wrong.
Most wattmeters have a VSWR table on the back, and if not, in the manual.
The nomographs in the Telewave 44A and Bird 43 manuals (two of the most common) both show a VSWR of about 1.75:1 for 34W/2.5W.
This converts to a RL of about -11.3dB
Another way is convert the forward and reflected power to dBM first.
34W = 15.31dBm, 2.5W = 3.98dBm.
RL = P1-P2 = 15.31 - 3.98 = 11.33dB
Regardless of the math, there's a problem in the antenna system.

As several have pointed out, the wattmeter can only read what it sees at the equipment end, and we can only infer what is happening at the antenna end by factoring in the insertion loss (assuming the feed line is OK).

Assuming ONLY 3bB insertion loss in the feedline, the antenna RL = -5.33dB, or a VSWR of about 3.4:-1.

Without measuring at the antenna you can't be 100% sure where the problem is unless the feedline is very short. Looks like a bad antenna, but could also be bad connectors, poor termination, etc.
LMR is nice cable, but if cut with a hacksaw you get all sorts of metallic debris in the foam, worse if it is using a flooded jacket (goop in the braid). Also, pin depth can cause problems. If connectors are not mated properly, ie., under or over torqued, you will have issues. I've seen lots of equipment destroyed by over-tightened N connectors, less so with DIN 7-16

Post by **VE3HKB** » Mon Nov 10, 2014 4:19 pm

Oops. 34W = 45.31dBm, not 15.31 (should have read dBW). Similarly 2.5W = 33.98dBm, not 3.98 (dBW). Keep forgetting dBm is referenced to milliwatts, not watts, a 30dB difference.
Formulas work out the same.

Post by **bh7juo** » Wed Nov 12, 2014 1:07 am

hello Max,I suggest you using SWR meter or power meter check like this:
first,connect meter between repeater TX and duplex in,duplex out I suggest to connect a dump load 50 OHM,and transmit,check FWD and

REF power.It measure repeater TX power and reflect from duplexer(means duplexer SWR).
second,replace dump load by antenna with cable which you want to use.And connect meter between duplexer out and cable connector.It measure duplexer out power(as know as duplexer loss) and cursory check the antenna SWR(because cable will affect SWR result).
third,connect meter between end of your cable and antenna input.It can check cable output power(cable loss) and actual antenna SWR.

Post by **xmo** » Wed Nov 12, 2014 5:48 pm

VE3HKB wrote: "I don't know why the previous calculation is wrong, but it is wrong..."
---------------------------------------------------------------------------------------------------

If you are referring to the numbers I posted - they're definitely wrong.

The return loss formula is correct : RL=10 log (P1/P2)

In this case RL = 10 log (34/2.5) = 11.335 dB

How did I get it wrong? (34/2.5) = 13.6 so somehow I copied that intermediate result before taking 10 log.

A Return Loss of 13.6 would be near an SWR of 1.5 but then I compounded the error by posting it as 23.6.

Bummer - I should have double checked the results. Let's see if I can do better this time.

From the correct return loss of 11.335 we can compute the VSWR.

First the reflection coefficient: r=antilog(-RL/20)

That computes to: r = 0.27118

Then VSWR = (1+r)/(1-r)

That computes to: VSWR = 1.744 which is almost exactly what your nomographs showed that it should be.

The conclusion that there is a problem in the antenna system is valid and consistent with the observed results that the balcony antenna performs better than the one on the roof.

Max · Post by **Max** » Wed Nov 12, 2014 6:42 pm

Once again i want to thank everyone for the valuable and educational input.
I think i have pin pointed what could be the problem.I have posted a couple of picture of the antenna i use and a close up of what i think happened.
We went on the roof a couple of months ago to try and adjust the vertical angle of the antenna as it was leaning a bit to one side.
We noticed the bolt that holds the antenna to the together had fallen out.It surprises me that this one bolt holds this antenna together.
We did find the bolt and put it back together.Roof time was limited so we did what we could.
After reviewing some pictures i noticed some black markings around hole where the missing bolt goes as well as the bottom of the antenna mast and if you look close you can see some around the ring with the ground planes.
It looks like the cable has been rubbing against bottom of the mast and with the high winds alot of movement could have allowed water in and who knows how bad it pulled on the connector and damaged the coax.
Soon as i can get some roof time which will be limited again,i think i will dismantle the antenna,check the coax and put the correct N connector on the cable and depending on the condition of the antenna,i might replace it it with the one i use on my balcony since i know it works well.

Max

jry · Post by **jry** » Thu Nov 13, 2014 6:18 am

That rusty pipe you are bolted to may not help much with the noise level. Google rf interference and rust

You may want to find something else to mount that antenna to.

Max · Post by **Max** » Thu Nov 13, 2014 6:33 am

The pipe the antenna is clamped to is galvanized steel that was painted,and the lower pipe i believe is a iron vent pipe.
This a picture of the main pipe before the antenna was mounted.

Max

Bill_G · Post by **Bill_G** » Thu Nov 13, 2014 6:47 am

I'm looking at the gps antennas in the background suggesting at least two other services colocate on the roof with you. Even after you resolve your transmission line problems, you may suffer some rcvr degradation.

On the black stuff around the base of your antenna, it could be zorch from an indirect lightning hit. ie: a discharge started but a bad crimp flamed off first inside the base the antenna saving your line and repeater. You may have difficulty taking it apart. Follow the example of the grounding system the other users are applying on the roof.

Max · Post by **Max** » Thu Nov 13, 2014 7:13 am

Are you suggesting the antenna could be damaged if it was a lighting strike ?

Max

Bill_G · Post by **Bill_G** » Thu Nov 13, 2014 7:36 am

Yep. You'll know when you take the connectors apart. If they are blackened with deformed center pins, you took a hit. Then it's a matter of testing the antenna to verify it is still usable.

Max · Post by **Max** » Thu Nov 13, 2014 8:02 am

When i take the connectors apart and inspect them,if i do find blacked center pins,how much coax would need to be cut back before replacing the connector ?

Max

Bill_G · Post by **Bill_G** » Thu Nov 13, 2014 8:11 am

Hard to say. Maybe none. Maybe the whole run. Put a wattmeter and dummy load on to check the vswr at the top and bottom of the line.

MSS-Dave · Post by **MSS-Dave** » Thu Nov 13, 2014 12:13 pm

I would go with if you see evidence of a lightning strike on the connector like a burnt center pin, that Comet/Diamond whatever is damaged inside. You may see minimal reflected power from the antenna but if 2 of the 3 sections internally are broke, that will be little to no gain. Those things just aren't built that well. If you could find a DB 408 or even a DB 404 surplus somewhere, it would help you tremendously. Additionally, the DB antennas are a DC ground type design that will survive years of lightning and corona discharge if the mount is grounded adequately.

Dave

Max · Post by **Max** » Mon Nov 24, 2014 4:08 pm

I was able to get some roof time Sunday and replaced the NCG Comet CA-712EFC with the NCG Comet CA-F72GF which was the one off my balcony that worked well.

I checked the connectors and did not see any evidence of a lightning strike.

Took the antenna apart to check it internally for any signs of damage.

The pictures below are the NCG Comet CA-712EFC i took apart.

I have never seen a antenna like this before.I counted 12 x 8.5" pieces of coax soldered together to make up the antenna.

The much smaller antenna i replaced it with does seem to work better,but still not what i was hoping for.

My thoughts are to replace the coax with LDF4 and perhaps look for a DB 404 for next spring when i can get back up on the roof.The weather is too much to go back up now.

Max

Bill_G · Post by **Bill_G** » Mon Nov 24, 2014 8:11 pm

Yep. That's how they make collinear antennas. It's a phased array.

Glad to be proven wrong about the lightning damage.

While you were up there, did you have your friend with the wattmeter over so you could measure vswr from the top end?

Max · Post by **Max** » Tue Nov 25, 2014 6:19 am

Unfortunately i was unable to get the tech guy with his meter that day.

Since most 4 bay folded dipole antennas are a little over my budget right now($500.00 +),what antenna would you recommend for my application with my repeater/duplexer in the $300.00 range ?

Max

Bill_G · Post by **Bill_G** » Tue Nov 25, 2014 7:03 am

I recommend you figure out where the high vswr is coming from. (big smile)

I totally understand personal budget versus performance. You get a Comet because that's what you can afford, and folded dipole is not within your range ... yet. I prefer lower gain in the 3-5dbd range. I prefer folded dipole over collinear because they are quieter, broader band, generally mechanically stronger, generally have adjustable patterns, and inherently grounded (lightning protection). OTOH, they ice up worse, get destroyed by ice easier, and can't take salt air very well.

Will · Post by **Will** » Tue Nov 25, 2014 12:46 pm

We use the Comtelco BS450XL3, and BS450XL4.5 series omni antennas
The ED 450-2 is the folded dipole series.

I have great results with the folded dipole series side mounted.

Max · Post by **Max** » Tue Nov 25, 2014 2:04 pm

Will,i looked up the Comtelco BS450XL4.5 series omni antenna @ 4.5db you suggested and noticed they all so have a BS450XL6-C @ 6db.
I guess in my younger days when i bought cars,i just had to have the one with the most Horse Power,seems i look at antenna's the same way,the more db the better.
How would you compare the 1-Comet CA-712EFC i was using to a 2-Comtelco BS450XL6-C @ 6db ?

Max

1-http://www.theantennafarm.com/catalog/n ... -1085.html
2-https://www.hol4g.com/ac/product.aspx?n ... 90663&sc=0

Will · Post by **Will** » Tue Nov 25, 2014 6:11 pm

I can not see how the Comet antenna can get 9 dB of gain in just ten feet and $ 129.95....

The real commercial antennas that do get 10 dBd gain are 18 feet long.

So if you take Comet's "claimed " gain as dBi, then it is really more like 6 dBd gain.
We have had way too many problems with some Comet antennas.

And there may be other problems in your antenna system. So some tests should be made comparing your Comet antenna against a known good antenna. Like we do on the antenna test range.

The DB 404 is over $ 500 and the Comtelco 6 dBd gain would be less than half that.

Max · Post by **Max** » Tue Nov 25, 2014 6:43 pm

Is this the DB 404 you are referring to ?

Max

http://www.theantennafarm.com/catalog/c ... -4267.html

Bill_G · Post by **Bill_G** » Tue Nov 25, 2014 9:55 pm

Yes. Great antenna.

Max · Post by **Max** » Wed Nov 26, 2014 6:26 am

I sure am getting alot of great info and i again want to thank all the members for their patience,i know alot of my question might seem trivial to most,but your relies are greatly appreciated.

If i don't ask,i'll never learn.

Many of you are recommending a dipole type of antenna and i see there is several types on the market.

What is the difference between the DB 404 Will & Bill_G and others recommended( http://www.theantennafarm.com/catalog/c ... -4267.html and this one http://www.jagelectromagnetics.com/JAG% ... SM_low.pdf.

I agree there is still something going on with my cable and i will replace that with Heliax LDF4 when the weather and roof time are favorable which might not be till spring.

Max

RFguy · Post by **RFguy** » Wed Nov 26, 2014 6:56 am

Looks like the JAG antenna is a knockoff of a Sinclair SD314. I wonder why it's only 6.45-7 dB gain where the Sinclair is 8.0.

http://www.sinclairtechnologies.com/cat ... aspx?id=34

The JAG looks like a decent unit, construction wise, but it's all about the quality of components and engineering. I probably would't use one for a public safety system, but would consider it for a ham system.

Bill_G · Post by **Bill_G** » Wed Nov 26, 2014 8:14 am

The Jag has fixed elements, and the DB404 has movable elements. The Jag has a cardioid pattern with emphasis on the element side of the mast. The DB404, as depicted in the photo, has an elliptical pattern along the axis between the elements. If you swivel one of the pairs 90 degrees, it becomes an omni.

Max · Post by **Max** » Fri Nov 28, 2014 1:32 pm

I got a quote for the JAG antenna that RFguy said looks like a knockoff of a Sinclair SD314.
Do you know how much the Sinclair model is ?

Max
(Nice first time buyer discount)

RFguy · Post by **RFguy** » Fri Nov 28, 2014 2:46 pm

Sinclair SD314 is $1,300 CDN.

Max · Post by **Max** » Fri Dec 05, 2014 6:00 pm

A friend of mine mounted a 4 bay on a elevator shaft,and drilled through the inch 8" reinforced concrete to mount the brackets for a antenna that weighs 20 pounds,and has antenna mount bracing on the other side of the concrete wall.
If I put up a 4 bay and can't drill through the wall,can I use good concrete anchor bolts with a good bracket and be ok ?
The mast on my 4 bay would be 9' and weigh about 15 pounds.

Max