Hi Chris:
On Thu, 04 Mar 1999 19:34:36 -0800, csnichol wrote:
I use on of these on my repeater. I got some conversion info from an
Engineer at Decibel
back in 95. The drawing is not an offical engineering drawing and has a
number mkt019/a
on it you might see if you can get it.
On one of the sheets that I have, there is a drawing number
040020 issue "G". I would have thought that the length of
the cables would have to be modified, as the cans were on
45.140 / 46.190, and they will be going up almost 8 megs?
Now I don't know if this drawing belongs to these exact
cavities, so some differences may crop up.
After your dimensions, I'll put in what is on my drawing:
Open the cans and trim the helix to 7 1/4 turns.
Pop rivet the cans back together
To get the cans in our band with the adjuster near mid range,
I shorted 2 turns of the helix at the "open" end. This way,
the cans can be returned to "stock". Is it better to just
trim the copper?
on the low freq side...
Can to Tee length 14 3/4
same ("A" on my drawing)
Shorted stub length 19 1/2
This is strange. My drawing shows a value of 15" with a
split up to 1 MHz, and no stub if 1 meg or higher?
Interconnect (Qty 2)
29 1/2
same
On the high freq side...
Can to Tee length 29 1/2
same
Open stub length 21 1/2
Mine shows 27" up to 1 meg, and no stub if 1 meg or
more.
Interconnect (Qty 2) 41 3/4
same
For the arms of the Y cable at the antenna port
41 3/4 Qty 2
same
I used the long stub to make the short ones.
I made new long stubs
I did not change anything alse in the harness as it was darn close and
it works for me.
I would like the duplexor to work as best it can Chris, so
do you think optimizing the dimensions for our band will yield
any better response?
If you cant get the document from decibel I will send you a copy.
I think our drawing are very close. All the cables are lettered
"A" to "E" in a chart and the chart has 3 rows, 400 to 600 Khz,
600 to 1000 Khz, and 1 meg or more (being the RX/TX separation).
My cans are rated from 45 to 50 megs, so increasing the
operating frequency by about 10%, should decrease the
length of the cables by that amount...no?
Do you have DB's web address?
Thanks for all the help Chris....
Tedd Doda CET
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