ICOM FL-30 Crystal Filter

[2E1IIP]

Hi guy's
I am hoping somebody can help with finding some information;
I am currently building a homebrew HF/VHF SSB Transceiver and managed to get my hands on an unused ICOM FL-30 Crystal filter for my I.F Stage, the problem is that I can not seem to find a datasheet for this filter.
My question is; what is the input/output impedance of the FL-30?

Any help will be grand

Best Regards

Rob

2E1IIP.

[KA4POL]

Hi Rob,

I'd contact Icom. It's always best to get it from the horse's mouth.

73

Dieter

[2E1IIP]

Hi Dieter, I will do that.

Best Regards

Rob.

[KB1GMX]

someone already posted some info on it...

go here http://1.bp.blogspot.com/_t5sYDhDV7AU/SLc7MHRDtVI/AAAAAAAAACA/WAy6nYUK3m8/s1600-h/ICOM+filters.jpg

click on the list to see it larger.

The filter was used in the IC-765 radio SSB 2.3khz at 9.0115mhz.

google found it as the 5th hit.

Allison

[2E1IIP]

Thanks for the info, already seen that site however it does not answer my question r.e the I/O impedence of the filter.
I will attempt to contact ICOM once again as they seem to busy to reply to my email, failing that I shall put it on the Spectrum Analyser and experiment with various transformer ratios until optimum performance is acheived.

Reagrds

Rob.

[KA4POL]

May be you can locate someone owning a Vector Network Analyzer like the VNWA3 being sold in the UK. This should allow you easily to perform your measurements. Slow/no replies from manufacturers are unfortunately quite usual.

73 Dieter

[G3RZP]

The input impedance unless correctly terminated won't help too much.

You need to connect to a sweeper and vary input and output resistances for best flatness to determine what it is.

[N0SYA]

A 47ohm resistor has been used to replace the 9MHz filters in some modified Icom R71A rx boxes to obtain a truly wide IF bandwidth. When I asked the mod creator why a 47ohm was employed, the reply was that different resistances were tried and stage loading watched untill no loading took place.

[KB1GMX]

Thanks for the info, already seen that site however it does not answer my question r.e the I/O impedence of the filter.
I will attempt to contact ICOM once again as they seem to busy to reply to my email, failing that I shall put it on the Spectrum Analyser and experiment with various transformer ratios until optimum performance is acheived.

Reagrds

Rob.

Well you missed that it was used in the 746.  Look at  their circuit for a clue.

Also to my experience filters like that are typically in the 250-600ohm range with
many around 400-500. If you have to go at it with a analyzer and tracking generator
that would be a good starting point.

Also some of those filters have or require capacitance at the terminations (4-50pf)
to "tuned them at the correct load impedance.


Allison

[K8AXW]

Rob: Contacting any large company by email is a 50/50 gamble on receiving the information you asked for.  It's too easy to simply blow you off with a flip answer.  This has been addressed in another forum here on eHam.com.  I commented in that forum that it was my opinion that the people who read email simply can't read.

I suggest you write a snail-mail letter to the home office in this country and then if you fail to get what you want, write another snail-mail letter to the home office in the country that builds the equipment.  In that letter, along with asking for the information you want, also mention that you received very little if any help from their USA home office. 

I can almost guarantee you that they won't want to hear this information!  Be cordial, be specific and avoid "flaming".  It might take you awhile to get what you want but quite often when you build gear, "time" can't be a factor.

Good luck!

[2E1IIP]

Hi Guy's, thank you for the replies.

Well I have spoke to ICOM UK HAM Radio division and they have informed me that an engineer will call me back with information on the FL-30.

However, I have found a company that produce a drop in replacement filter for the FL-30, they have informed me that the I/O Impedance is 1000 Ohms, therefore I will need to wind a transformer with a turns ratio of 1.336 thus 10 turns on the primary (560R) will require 13.5 Turns on the secondary.

Once again thank you for the assistance with this query, once ICOM contact me I shall compare their data with that of the company that supply an equivalent device and I will report back.

Best Regards

Rob.

[KA4POL]

Rob,

it might be interesting for others to have a link to that company supplying the replacement, if you don't mind. Usually thee are obsolescence issues coming up sooner or later anyway.

Thanks

Dieter

[2E1IIP]

Here is the link for the filter in question.

http://www.inrad.net/product.php?productid=123&cat=4&page=1

Regards

Rob.

[KA4POL]

Thanks a lot for the very interesting link. They even got Heathkit replacement parts.

73 Dieter

[BG2FX]

I can offer 9.0115Filter    Modeled afterFL-70production

一、Technology index：

1   Shape dimension   H-7
2   Center frequency   9.0115MHz
3   Poles number   8
4   Bandpass width   ±1.2KHz/6dB
5   Insertion loss   5.0dB
6   Belt in the fluctuation   2.0dB
7   Stopband width   +2.2K， -2.4KHz/50dB
8   Input/output impedance   800Ω//12.0PF
9   Temperature range   -10~+60℃

 
H-7   25   12   18   32   2.5   0.43