The AM Forum

I was given a Bird model 43 from work. It's like new! It has a custom slug for 50-90 MHz, 5 watts. This was used to align the modulator in a laser trimmer.

OK well I need to shop for a 5KW slug. Looks like some Cable Dynamics ones on e-ay for $160 or so. 10KW is the same price, but I can't see ever making >5KW under any reasonable circumstance.

But the big question is: The meter has BNC connectors on it. There seem to be two un-used N connectors there in the box too, but they are not installed.

What is the power rating for a BNC connector?

For an N connector?

Do the connectors change out easily? I don't want to start taking this still-calibrated instrument apart till I know what to do.

You Lucky Dog!  Those are probably what Bird calls their Quick Change Connectors.  They have BNC, Type N, SO-239, etc.  I think all you need to do is to take the four screws out of the flange and pull the BNC off and install the N's or whatever type you want.

A type N will take 5 KW at HF. Look up Bird switches to see type N derating above 30 MHz.  It is very easy to swap out connectors and you can still buy new ones. The back side of the connector plugs into the tube that goes through the coupler. If you love PL259s just get a couple adapters.

Excellent!! Thanks!

what would be the next level above N's ? LNC?

I've seen both HN and LC series for the 43 meter.

I own a set of 7/8" EIA for mine.

dg

I think your coax will run out of steam before the type n. HN is a nice connector also with a bigger contact. I wouldn't worry about it unless you are going RG393 or hardline.

Ive run 5KW thru quality brand N's here many times up thru 10M testing customer repair jobs or back when I could make a buck building 2X 4-1000A or 3CX3000A7 amps. A few 6M conversions Ive done at 2500-3000W havent got the connectors more than barely above ambient even after a 30 or 60 second keydown smoke test. I do turn the fans on the 3kw Bird/RCA dummy load just to keep all those tasty PCB's happy :o

The HN makes a fine HV connector for your PS and true mil spec RG-213 will handle any voltage that any sane ham would be using.....that means 10kv is no sweat. ;D

The PL-259/SO-239 can also handle 5KW on HF IF its mil spec Amphenol or clone, or Amphenol Teflon. Ive smoked most of the others including some of the junk on commercial amps even at 2000W.

Carl

Yup I use HN for the plate supply. I bought a few panel sockets with a long teflon  insulator

Dont forget the C connector, largely used by the military.  Its just a big BNC. These connectors are widely available and the QC connectors for C connectors are readily  available at reasonable prices.

I picked up a box of 100  Delta  Silver plated C connectors for 20 dollars on  a auction site. There is also 2 ratings of C connector available. The 2 ratings are  1000 Volts RMS and High voltage 3000 volts RMS. This connector   is available  for any cable you care to mention.

As for the Bird Elements. There is a Bird PEP board that extends the range of the element by  a factor of 2 or 5. I have been using this board for a while, I have had no element damage.  It certainly is a money saver. I have been using a 500 watt element at 2500 watts into a dummy load with no problems. The board has a inbuilt calibrator making set up of the elements very easy. In reality I just use 2 elements 50 watts and 500 watts. These 2 elements with multiplication  covers the HF range with enough precision and range by just flicking switches, just like the Bird 4410A.

On another point. I just purchased a Bird 160 meter 2500 watt Element. I  just finnished comparing it to my HF 2500 watt element. It reads exactly the same at VSWR  levels of 1:1, 1:5 and 2:1:1. After reading how bad Bird elements are on 160 meters, I decided to verify this for myself. I just wasted a lot of money!

Another waste of money was my Bird 4431 with inbuilt sampler. Its just a piece of coax stuffed down a tube whose distance is varied by a screw. The connections  break very easily, so be very careful when buying one second hand. The replacement parts are very expensive.

If you need a reliable non rectified sampler in form of a Bird element look at the Coaxial Dynamics non directional  X-tractors. Its cheaper than the Bird inline HF sampler, and its main power limitation is the line section size. I have a -45db 87005 non directional extractor. This xtractor is rarely mentioned because everyone wants to sell you the more expensive Bird line sampler.


73
Craig

I was not aware of these extractors!

I think I paid $29 for a NIB Bird version a few years ago on Fleabay.

Carl

We use a couple C connectors at work on our lower frequency stuff. The females seem to have a short life. Mechanical stress seems to take them out. BNC connectors are handy but leak.

I've been using BNCs @ 500 watt level for decades.  Never had a problem.  Maybe I need a dope slap ;D  I've recently "upgraded" to UHF connectors - mostly 'cause the premade stuff comes that way and I've developed a lazy streak in me.

Al

The new QST has a -45dB coupler article. I built one similar 25 years in a lab where I worked.  Still use it.

Carl

That looks easy to build. ask and you shall receive. QST also reviewed the J-pole from Arrow Antennas. I have one and it does work extremely well.

I'll jump in here with a good word for the Arrow OSJ-146/440. I use two of them at the home QTH -- one as a primary antenna for a secondary radio (yes that makes sense), and the other as a "weather antenna" for my primary 2 meter radio. I also carry one in the toolbox on the pickup for deployment if required in an emergency situation, or for use on the bike races that our club provides comms for each year. Great antennas. And Al is a good guy who deserves our business.

73,
ldb

BNC and type N should exhibit similar power capabilities due to similar dimensions.

The BNC and the N connector are for all intents and purposes the same thing.

Look, plug an N into a BNC, or vice versa.

I've run 3CX3000s on AM with N connectors.


--Shane