Good Day all!
My "new" (it began building in 1985) receiver is very nearly finished and
ready for use.
It was long delayed by family events and a multitude of synthesiser
problems, but now we have DDS synthesisers this is no longer an issue.
Just a few AGC attack problems to iron out and some tuned circuits at the
front end to arrange.
I have some very nice 12.5mm toroids (violet) which work Very well from 1
to 20 MHz but take a severe dive in performance above there.
What I need is a source of toroids of the same size but with a frequency
range with high Q from say 15 to 60 Mhz. These are for the bandpass tuned
rf filter and the 1st IF @ 45 MHz.
Anyone got any ideas where I might obtain a few out here in NZ.
None of the local suppliers have anything like this and they are also
generally very ignorant of the proper use of toroids especially at HF.
Any suggestions very gratefully received.
Regards Clifford Wright ZL1BDA ex G3NIA

On 25/08/2011 9:03 PM, clifford wright wrote:
I have some very nice 12.5mm toroids (violet) which work Very well from
1 to 20 MHz but take a severe dive in performance above there. What I
need is a source of toroids of the same size but with a frequency range
with high Q from say 15 to 60 Mhz. These are for the bandpass tuned rf
filter and the 1st IF @ 45 MHz.
Anyone got any ideas where I might obtain a few out here in NZ. None of
the local suppliers have anything like this and they are also generally
very ignorant of the proper use of toroids especially at HF. Any
suggestions very gratefully received.

I got a few HF/VHF toroids recently from http://rockby.com.au.

Just make sure you verify that the mix you select is correct for the
purpose (resonant, not transformer) you need, and has the permeability
you want. There's a lot of confusing information on the net about what
different mixes are good for, and I'm only just starting to get my head
around it.

Rockby stock # 25651 is smaller than you want, but mix 12, mu=3, which
should be good in resonant circuits from 20-200MHz, if I have my facts
straight. I also have some stock #25298, mu=40 and mix 63, which should
be ok in resonant circuits from 10-80MHz, and in transformers to 800MHz.

If anyone can verify or discredit the above suitabilities, I'd like to
know before I spend too much time playing with circuits around these
(I haven't found time yet, still trying to figure out how to make decent
PCBs, necessary to get a ground plane at 2m).

Clifford Heath.

atec77 wrote in :

On 25/08/2011 9:03 PM, clifford wright wrote:
Good Day all!
My "new" (it began building in 1985) receiver is very nearly finished
and ready for use.
It was long delayed by family events and a multitude of synthesiser
problems, but now we have DDS synthesisers this is no longer an
issue.
Just a few AGC attack problems to iron out and some tuned circuits
at the
front end to arrange.
I have some very nice 12.5mm toroids (violet) which work Very well
from 1 to 20 MHz but take a severe dive in performance above there.
What I need is a source of toroids of the same size but with a
frequency range with high Q from say 15 to 60 Mhz. These are for the
bandpass tuned rf filter and the 1st IF @ 45 MHz.
Anyone got any ideas where I might obtain a few out here in NZ.
None of the local suppliers have anything like this and they are also
generally very ignorant of the proper use of toroids especially at
HF. Any suggestions very gratefully received.
Regards Clifford Wright ZL1BDA ex G3NIA
I would email amidon directly


Thanks for the suggestion Amidon were very helpful and have low postage
rates.
ZL1BDA