Bob it may be the same one. It measures 9 X 9 1/4 inches and is fairly heavy.
The output to input port loss is 20 dB at the ends of it's coverage and 40 dB
at the tuned frequency. The 3 dB bandwidth is about 3 Mhz.
Do you have tuning instructions?
Joe
At 03:17 PM 11/22/2004 -0800, you wrote:
>At 11/21/2004 11:01 AM, you wrote:
>
> >Joe,
> >
> >I suspect that RJ Communications is no longer in business, so finding
> >tech data on that circulator may be difficult.
>
>I know someone who has one of these & sold many more (if we're talking the
>same model; is it rather large for a VHF circulator?). IIRC the
>performance on 2 meters was excellent: 0.3 dB forward loss & ~30 dB reverse.
>
>
> >The typical ferrite circulator doesn't dissipate much power itself; it's
> >the load(s) attached to the reject port that determines its power
> >rating.
>
>If you expect it to handle 100% reflected power, yes. Circulators do have
>their own power ratings - you can't slap a 1 KW load on one & expect it to
>handle that much power. The lesser of the two (circulator & load)
>determines the power it can handle under any conditions, but in a pinch you
>can put as much power in as the circulator can handle so long as the power
>reflected back does not exceed the rating of the load. Of course if your
>antenna unexpectedly goes bad you'll fry the circulator load.
>
>
> >It's important that a circulator be correctly tuned to operate
> >efficiently. The label 140-180 MHz refers to the range of that
> >particular design, and should not be taken to mean that it will work at
> >any frequency in that range.
>
>Again, if we're talking about the same circulator, it's rather broad. It
>worked just fine all across the 2 meter band & then some, with no tuning.
>
> > Nearly all of the circulators I have taken
> >out of service from the 152 MHz band would not tune more than 2 MHz
> >either side of the frequency marked on the unit. I had to send them
> >back to the manufacturer to be reworked for operation on the 2m band.
> >This rework involved an exchange of magnets, pole pieces, and a new
> >garnet ground to a specific tolerance.
> >
> >A network analyzer is a must for tuning a circulator, especially a dual
> >circulator, since some measurements look for transmission peaks while
> >others look for return-loss peaks. A spectrum analyzer will not suffice
> >for this tuning task, unless it is used with a return-loss bridge.
>
>This is not true. I've tuned all my circulators using only transmission
>measurements (forward & reverse).
>
>Bob NO6B
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
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