DB-420 16 bay UHF folded dipole.

[W2NAP]

I was able to snag one of these for FREE! Not sure exactly who makes it. I know commscope still makes a 420, but this one is a bit older. only one snag. center pin on the 75 ohm N female is borked and gotta be replaced. (for those who don't know they use 75Ohm RG-11 for the harness)

Might be a long shot but before I go and dump $30 for a new connector anyone got a center pin for a 75ohm N female laying around?

[WØTKX]

Sorry. Plenty of males, no females.

Typical Ham Radio issue. ;)

[KG4CGC]

Sorry. Plenty of males, no females.

Typical Ham Radio issue. ;)

Fiesta de la chorizo.

[W2NAP]

Sorry. Plenty of males, no females.

Typical Ham Radio issue. ;)

needs moar females.

[K7SGJ]

More cowbell.

[N8YX]

Can you get a picture of the damaged connector and post it, Tony?

[W2NAP]

Can you get a picture of the damaged connector and post it, Tony?

yeah ill have to take a trip up to the shop. give me a day or two.

[W2NAP]

Not able to get up there today. but this is the connector http://www.pasternack.com/n-female-standard-rg11-rg144-rg216-connector-pe4515-p.aspx

[K7SGJ]

I was able to snag one of these for FREE! Not sure exactly who makes it. I know commscope still makes a 420, but this one is a bit older. only one snag. center pin on the 75 ohm N female is borked and gotta be replaced. (for those who don't know they use 75Ohm RG-11 for the harness)

Might be a long shot but before I go and dump $30 for a new connector anyone got a center pin for a 75ohm N female laying around?

I can send you a new Amphenol 82-63-RFX. Although made for RG-8, 213, etc., the poop sheet shows it will work with 216 which is 75 ohm. If you want to try replacing the entire connector or just see it the center conductor will work, send me an address and I will stuff it in an envelope and toss it at the pony express lady when she goes bobbin by.

[W2NAP]

I can send you a new Amphenol 82-63-RFX. Although made for RG-8, 213, etc., the poop sheet shows it will work with 216 which is 75 ohm. If you want to try replacing the entire connector or just see it the center conductor will work, send me an address and I will stuff it in an envelope and toss it at the pony express lady when she goes bobbin by.

is that connector 75ohm? from my memory 75ohm connector wont mate well with the 50ohm. (from my memory the N female pin is bigger on the 75ohm vs 50ohm.)

[K7SGJ]

is that connector 75ohm? from my memory 75ohm connector wont mate well with the 50ohm. (from my memory the N female pin is bigger on the 75ohm vs 50ohm.)

I'm not positive. One place shows it being compatible with RG 216 which is 75 ohm, but many others don't list that. I know this will work with RG-8, 213, 214, and those series, but can you adapt it at all? Or, can you put another style of connector on the antenna? I know N is best, but if you no gots, then it's on to plan "B".

[W2NAP]

yeah way this harness is. the dipole interconnects are 75ohm rg-11 with a 75ohm N male/N female to connect the sets of 4 to make 8. at the end is a 50ohm n female where the hardline connects..

what I worry about is if I did swap the bay interconnect out to 50ohm it throwing off the impedance

[K7SGJ]

yeah way this harness is. the dipole interconnects are 75ohm rg-11 with a 75ohm N male/N female to connect the sets of 4 to make 8. at the end is a 50ohm n female where the hardline connects..

what I worry about is if I did swap the bay interconnect out to 50ohm it throwing off the impedance

That would certainly be a concern. I'm wondering why a commercial 400 MHz antenna would have 75 ohm components to join the sections. May it have been changed out at some time? The only other idea would be to put an antenna analyzer on it and see what the impedance at each connector really is, and then break out the abacus.

I have seen multi section antennas like that, where the top section is sold as a lower gain version of a two stage version, but have never messed around with them to see what the Z for each stage is. I'm sure that for combining them, the matching considerations were part of the design.

But then, I could be full of shit, too.

[WØTKX]

The joining connections are likely at 75 ohms as part of the phasing design. Much simpler, but I ran a pair of home brew phased loops on 2 meters for a long time till it blew down. Used RG-6 for the phasing harness. The 75 ohm matching sections are common.

http://www.hamuniverse.com/zs1iphasing_harness_diagram.jpg

[NQ6U]

The joining connections are likely at 75 ohms as part of the phasing design. Much simpler, but I ran a pair of home brew phased loops on 2 meters for a long time till it blew down. Used RG-6 for the phasing harness. The 75 ohm matching sections are common.

This, exactly.

[W3WN]

Not able to get up there today. but this is the connector http://www.pasternack.com/n-female-standard-rg11-rg144-rg216-connector-pe4515-p.aspx $25 for a connector? For an "F" connector? What are they making it out of, gold pressed latinum? :wtf:

Seriously, though, if you know a ham who works at a broadcast station, or in another RF related professional field, see if they have some of these around.

[W2NAP]

$25 for a connector? For an "F" connector? What are they making it out of, gold pressed latinum? :wtf:

Seriously, though, if you know a ham who works at a broadcast station, or in another RF related professional field, see if they have some of these around.

Actually it is a N type female 75ohm and believe me I checked my local guys. I can get plenty of 50ohm stuff from N to 7/16 DIN to EIA but 75 ohm is a dry bed.

SGJ - This antenna is actually a 16 bay folded dipole. it has dual folded dipoles on each bay in a total of 8 bays of dual folded dipoles. 9.2 db gain in omni or 11.2 db in a offset. the 75 ohm coax is the harness. and to interconnect the 2 sets of 4 dual bays they use 75 ohm connectors. (which is where the N female/75 center pin is borked) some jackass goobered it up thus I ended up with is for free. and plan to use it on my repeater.

I still aint been able to get to the shop to get pics of it. $4 a gal gas kinda kills travel over here.

[PA5COR]

4$ per gallon? try Netherlands.
Price per gallon of premium gasoline: $8.26
Price change since last quarter: -12%
Most-expensive-gas rank: #5
Pain-at-the-pump rank: #41
Netherlands has the most bicycles per capita in the world. Rows upon rows of them stand parked at train stations, museums and national parks. A vast infrastructure of bike paths and lanes, tunnels and traffic signals makes cycling easy to adopt.
The average daily income in the Netherlands is $131. The share of a day's wages needed to buy a gallon of gas is 6.3 percent.

USA:

Price per gallon of premium gasoline: $3.75
Price change since last quarter: -11%
Most-expensive-gas rank: #49
Pain-at-the-pump rank: #55

The average daily income in the U.S. is $136, and the share of a day's wages needed to buy a gallon of gas is 2.8 percent.

And still complaining? ;)

[W2NAP]

4$ per gallon? try Netherlands.
Price per gallon of premium gasoline: $8.26
Price change since last quarter: -12%
Most-expensive-gas rank: #5
Pain-at-the-pump rank: #41
Netherlands has the most bicycles per capita in the world. Rows upon rows of them stand parked at train stations, museums and national parks. A vast infrastructure of bike paths and lanes, tunnels and traffic signals makes cycling easy to adopt.
The average daily income in the Netherlands is $131. The share of a day's wages needed to buy a gallon of gas is 6.3 percent.

USA:

Price per gallon of premium gasoline: $3.75
Price change since last quarter: -11%
Most-expensive-gas rank: #49
Pain-at-the-pump rank: #55

The average daily income in the U.S. is $136, and the share of a day's wages needed to buy a gallon of gas is 2.8 percent.

And still complaining? ;)

yeah I am still complaining. Very very very few clear $136 a day... more like avg daily income is about $50 and lets not forget a lot of people lucky to have a job (remember we have a real un-employment rate 30-40%) have to drive at least 1 hour or more away one way... many have to drive 2 hours away. About the only people making $136 a day are people working for the government or drug dealers.

Lets also not forget the Netherlands are only 16,039 sq mi in size. where as Indiana alone is 36,418 sq mi so we are just over twice the size of the Netherlands.. then add in a chunk of the surrounding states cause many people do travel to OH,KY,MI for work. so you get more mi2 added to the number. (and yes a good majority who do travel to other states for work make at or close to min wage.)

So yes $4 a gallon kills us. oh and we have over a billion barrels of oil under our feet here. so we see no excuse for $4 a gallon. (maybe $1)

Now add in Bicycles may work in the Netherlands but won't here. Simple fact is you roll into the wrong place and you are going to die or get the shit beat out of you and robbed. I don't think anyone in the Netherlands will kill someone for a dollar here people will.

[kb2vxa]

Oh stop complaining and let's get back to the subject. If you're having so much trouble mating 75 ohm connectors with 50 ohm ones, why not go 75 ohms all the way? 75 ohm coax terminated with a 50 ohm pure resistive load will give a 1.5:1 SWR. Since every antenna has some reactance, a good match is usually 1.2:1, so in any case the end result is always well within acceptable limits. I've seen hams using CATV hard line spool ends with excellent results, the extremely low loss characteristics more than make up for a little SWR, VERY little BTW.

[WØTKX]

http://www.commscope.com/catalog/andrew/product_details.aspx?id=15460&tab=3

[W2NAP]

Oh stop complaining and let's get back to the subject. If you're having so much trouble mating 75 ohm connectors with 50 ohm ones, why not go 75 ohms all the way? 75 ohm coax terminated with a 50 ohm pure resistive load will give a 1.5:1 SWR. Since every antenna has some reactance, a good match is usually 1.2:1, so in any case the end result is always well within acceptable limits. I've seen hams using CATV hard line spool ends with excellent results, the extremely low loss characteristics more than make up for a little SWR, VERY little BTW.

AH, if this was just a run of feedline I would. but since this is a phasing harness doing so could actually mess up the phasing. all the phase harness is 75 ohm rg-11. with 75 ohm (N) connectors. I have been told to keep the interconnect between the 2 sets of harness 75 ohm connectors or bad things happen end up with a impedance bump..

http://www.commscope.com/catalog/imagesCache/0000008/t006_r01645_v4.jpg is the type of Antenna (still unsure of who actually made it) TKX posted a link to the antenna type.

[WØTKX]

Yea, the phasing harness lengths are critical. It has to do with getting the timing right with a carefully trimmed length of a cable with a known (preferably measured) velocity factor. Knowing it's RG-11 helps.

That being said, a single 50 Ohm connector in a 75 Ohm harness would probably not change too much. You could modify the harness slightly to accommodate the small change... and you'd have to measure it.

Much simpler to get the 75 Ohm connector. But I wonder how much it would change?

Every harness I have made I used extra coax and connectors, cut and measured a few till I got it just right, and then made 'em. So far, just two meters, and the MFJ analyzer showed me what was going on really well.

Modified the 2m loop design from this page, for a pair of 2m loops...

http://www.kr1st.com/2mhalo.htm

[W2NAP]

I figure its best to leave the harness with what the guys at the factory used.. Those guys that made this thing are a shitload smarter then I am lol.

I guess a center pin will turn up eventually or ill just have to scrape more cash from somewhere and buy a damn replacement connector..