Hello Joerg, nice to meet you for the first time.

Bill W0IYH

"Joerg" wrote in message
...
Hello William,

Get a copy of Amidon's catalog which gives detailed suggestions for
powdered iron and ferrite materials, based on many years of experience.
www.amidoncorp.com


Absolutely. I literally wore one of those catalogs to the point where you
could see through several pages.

Then there are the ARRL Handbook and their Antenna Book. Both well worth
every penny.

Regards, Joerg

http://www.analogconsultants.com

Hi Guys,
Results of the build and test were that the 7Mhz HPF worked very well with
the "6" grade cores, but the 20Mhz LPF was crap (it used #6 as well). It
started to roll off at 20Mhz as expected, dropped smoothly to -10dB by the
time it got to 40Mhz, then stayed at 10dB at all frequencies above 40Mhz.
I suppose the core should be a grade #10 or #12 instead of #6? or perhaps
just a normal air core?
JEFF


"Jeff" wrote in message
...
Thanks for all the suggestions. Ive got some Amidon T68-6 toroids to wind
up, and will test the completed filter on a spectrum analyser next week.
JEFF

"Jeff" wrote in message
...
Hi,
Im confused regarding the choice of iron powder toroid for a 7Mhz high
pass
filter. I need to use a small size (T68) toroid. For the freq range,
some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice
there.
Any suggestions as to the relative differences and reasons to choose
between
grades 2 and 6 for the HPF in T68 size?
Thanks,
JEFF

"Jeff" wrote in message
...
Hi Guys,
Results of the build and test were that the 7Mhz HPF worked very well with
the "6" grade cores, but the 20Mhz LPF was crap (it used #6 as well). It
started to roll off at 20Mhz as expected, dropped smoothly to -10dB by the
time it got to 40Mhz, then stayed at 10dB at all frequencies above 40Mhz.
I suppose the core should be a grade #10 or #12 instead of #6? or perhaps
just a normal air core?
JEFF

Then you haven't built the filter that you designed. The choice of core
material will not affect the blow-by. If you measured the inductors at a low
frequency, I would be pretty certain that you have way too much inductance
at 20-40 MHz.

W4ZCB

Hello Bill,

Hello Joerg, nice to meet you for the first time.


Likewise. You name sounds very familiar, IIRC from a book about design
of HF gear. Didn't you work at Collins in the good old days when they
had mechanical filters in their gear?

Regards, Joerg

http://www.analogconsultants.com

Yes. I started at Collins Radio engineering department in 1964 and retired
from Rockwell Collins in 1990. For more info search Google for my name and
my call sign. See QRZ.COM for W0IYH. See www.noblepub.com.

Bill W0IYH

"Joerg" wrote in message
t...
Hello Bill,

Hello Joerg, nice to meet you for the first time.


Likewise. You name sounds very familiar, IIRC from a book about design of
HF gear. Didn't you work at Collins in the good old days when they had
mechanical filters in their gear?

Regards, Joerg

http://www.analogconsultants.com

"William E. Sabin" wrote:

Yes. I started at Collins Radio engineering department in 1964 and retired
from Rockwell Collins in 1990. For more info search Google for my name and
my call sign. See QRZ.COM for W0IYH. See www.noblepub.com.

Bill W0IYH


Did you ever work on their microwave receiver designs?

--
?

Michael A. Terrell
Central Florida

Hello, Mike,

I had a little experience with some military L-band RF design (JTIDS), but
that is about all. I have also designed miniature lumped-element filters
for the 3 GHz region. But most of my work and also my ham radio experience
have been at HF. Also, I am mostly, but not entirely, an analog specialist,
which has put me somewhat into the Jurassic Age.

Bill W0IYH

"Michael A. Terrell" wrote in message
...
"William E. Sabin" wrote:

Yes. I started at Collins Radio engineering department in 1964 and
retired
from Rockwell Collins in 1990. For more info search Google for my name
and
my call sign. See QRZ.COM for W0IYH. See www.noblepub.com.

Bill W0IYH


Did you ever work on their microwave receiver designs?

--
?

Michael A. Terrell
Central Florida

Hello Bill,

... Also, I am mostly, but not entirely, an analog specialist,
which has put me somewhat into the Jurassic Age.


Not really. Newly minted engineers know remarkably little about analog
techniques. Yet at the beginning and the end of circuits stuff usually
needs to connect to the analog world. So don't be surprised when someone
begs you to do just one more stint when you are past 90.

Then again a SW engineer once told me that nothing is truly analog.
There is always that smallest digital step, the quantum.

Regards, Joerg

http://www.analogconsultants.com

"William E. Sabin" wrote:

Hello, Mike,

I had a little experience with some military L-band RF design (JTIDS), but
that is about all. I have also designed miniature lumped-element filters
for the 3 GHz region. But most of my work and also my ham radio experience
have been at HF. Also, I am mostly, but not entirely, an analog specialist,
which has put me somewhat into the Jurassic Age.

Bill W0IYH


There is no reason to apologize for being good with analog. ;-) I
worked as a broadcast engineer during the time they announced the first
memory chip, (1101) which was a slow, noisy 256 bit * 1 DRAM with very
critical timing. I also did analog and digital work on the microwave
equipment built at Microdyne, before L3-Com closed the Ocala plant.

The reason I asked about the microwave equipment, I would like to
meet the people who designed the C-band CATV receivers I had to maintain
in the '80s. I always loved Collins equipment, till I ran into those
radios. They had a horrible failure rate, and took over six months to
have serviced by Collins. I think I still have a set of manuals for
the fixed tuned, and the agile models. I started repairing them for
United Video in 1982, and could return most of them to service the same
day.


--
?

Michael A. Terrell
Central Florida

Hello Michael,

There is no reason to apologize for being good with analog. ;-) I
worked as a broadcast engineer during the time they announced the first
memory chip, (1101) which was a slow, noisy 256 bit * 1 DRAM with very
critical timing. I also did analog and digital work on the microwave
equipment built at Microdyne, before L3-Com closed the Ocala plant.


Seems you started with digital stuff a year or two earlier than I did.
My first RAM had a whopping 1024 bits. Not bytes, bits. 21...something,
I could look it up since the device where its in still works.


The reason I asked about the microwave equipment, I would like to
meet the people who designed the C-band CATV receivers I had to maintain
in the '80s. I always loved Collins equipment, till I ran into those
radios. They had a horrible failure rate, ...


But their HF radios were quite reliable. Unfortunately at that time out
of my budget range, and so were those nice mechanical filters :-(

Regards, Joerg

http://www.analogconsultants.com