KitsAndParts.Com Forum

I've been reading up on KD1JV power and SWR kit.  I just found your directional coupler swr bridge.  I'm looking to make a bridge for 2 m band so I can learn to make antennas more efficient.
Can you kit be modified for 2 meter or should I keep trying to get one of KD1JV's kits?
Rob

Diz,

Is the meter output of the bridge in the 50uV range, 200uV range, or some other?

Thanks,
Greg
ki4mmm

Thanks Diz - I have several of those little 3/4x2" rectangular 200uA meters so it sounds like I outta be able to put a couple of them to use.....

Greg
ki4mmm

Hey Greg!
I talked to you yesterday and you didn't tell me you made a new Diz kit.
Bad Boy!
Leonard

kc0wox wrote:

Hey Greg!
I talked to you yesterday and you didn't tell me you made a new Diz kit.
Bad Boy!
Leonard

We we're so busy talking about different projects that I didn't remember this one.  A week before that, I finished building all of the modules needed for a transceiver (just about every module Diz offers except the 5W CW amp) ;-).

I've got a few pairs of 200uA meters left if anyone needs some (maybe trade for a small component or two?).  I'll have mine mounted in a box in a few days and will post a picture.  I am going to do dangling coax w/ BNC for the input/output so I can just plug it straight into my rigs and tuners, not needing separate cables.

Greg
ki4mmm

k3jls wrote:

Hi Diz,

I have a question about your directional coupler.  I'm building an automatic tuner for a mag loop antenna driven by a stepper motor.  So far, it works very, very well.

What I need, however, is a good directional coupler that I can place in an out-of-the way spot to both eliminate any possible RF contamination of the microprocessor (none detected thusfar) and to remove another pair of coax cables from the desktop.

I was wondering if your directional coupler - designed for a max power of 10 watts - would work in a 100 watt HF application if I replaced the 1/4 watt resistors with 10 watt units.  Would everything else on the board hold up OK??

If so, I'll place my order tomorrow (HIHI).

Thanks, in advance, for your interest and help.

73's - Joe - K3JLS

Hi Joe,
I think I answered this question via regular email...did not se the forum question...sorry.
For higher power, you would need to change the toroids to -61 or -2 material and increase the multiturn windings.
Also increase the 50 ohm resistors to 1 or 2 watts.
-Diz

My version of the bridge with two cheap meters from Dans Small Parts and Kits
http://www.danssmallpartsandkits.net/ (Dan's is closed until February)
Yes, I know they are 'S' meters but they tell me what I need to know at a glance -
mainly that I'm not transmitting into a high SWR. The top is forward power and the
bottom is reverse. I calibrated them as per instructions. This is a simple kit to build
and has already paid for itself in my SW20+

wa2mze wrote:

So 'stock' this bridge is for < 10W?  And it can be modified for higher power?

Hi Ken,

Right above my first picture, Diz has an answer to that question.

Tom, ak2b

wa2mze wrote:

Theres quite a bit of difference between -61 and -2 material!
-2 is the RED powdered iron material with a large AL good for up to about 10 mhz.
-61 is FERRITE with lower AL than -43, but sill a lot higher than -2 and generally rated quite a bit
lower in frequency.  Type 43 and 61 are used in broadband transformers and power inverters, while
2 type is used in tuned circuit transformers.  I suppose type 2 could be used in broad band transformers
but it's loss would be higher and I'm not sure about the frequency range in this mode.
Maybe Diz can clear this up for me....

-43 material has the highest loss. Next is -61 and -2 has the lowest loss.
Don't be afraid to experiment
-Diz

wa2mze wrote:

That seems the opposite of what we want, IE: for low power you would want the lowest loss so as to be able to drive the meters and for high power you'd want the highest loss since you don't need much left to drive the meters.  Yet you've got it backwards.

Not exactly

At QRP levels, I am not concerned about heating (loss) of the toroid core.
The -43 materials works BEST for broadband use; excellent for low power; low heating.
At higher power levels, the -43 material gets too hot so we use -61 or -2 material

The -43 may have more losses but I am not concerned about 10 percent loss which equates to NIL at the receiver end.

The more power, the lower the AL value (of the  toroid)  should be to prevent heating.
We are talking about a STOCKTON BRIDGE here.

73, Diz

I found some with a Google search, but they cost BIG money, If you use CB meters like Tom has shown they will be cheap. They could be had used from your local CB Hack shop cheap enough I would think, and as Tom has noted Dan's Small Parts will be closed for awhile yet.

aj4oe wrote:

Any one know where I can locate 'small panel meters' for the swr bridge, small enough to fit on an Altoids tin?

Thanks for your time and help...

Rex, AJ4OE

Ebay is your friend for parts! I buy most of my common stuff from there.
Leonard