I just went to the Digi-Key site and checked each value:
Enter "polypropylene capacitor" in the part number search window.
Click "film (4,665 items)"
Highlight "Panasonic" and "Apply Filters"
In the ECW series (metallized polypropylene) all values are available and
in-stock except for...
- the 3000 pF value which is available in the recommended ECQ series and
- the 1300 pF value which can be created by two 2700-pF units in series or a
3300 pf // 2200 pF and still have acceptable tolerances and there are other
I'll see if I can still get a tweak into Chapter 11's material for 2012 to
specify just "polypropylene film" capacitors. I have built this very filter
using silvered-mica caps, as well, and air-wound coils so that it could be
used in-line with the transmitter.
On the broader subject, the ARRL really doesn't have the resources to verify
the availability of parts in projects. I'm happy to hear about alternate
sources and substitutes, though, and try to get the word out. As with
nearly all ham radio projects, the builder needs to approach published
projects (from any source) with the understanding that they are not kits and
may require "flexibility". We're all bright guys and gals here and can
figure this out or ask for help!
73, Ward N0AX
Lead Editor, ARRL Handbook
* - to find a parallel value of capacitor, Cpar, that will combine with a
given value, Cgiven, to produce a desired value, Cdes:
Cpar = (Cdes x Cgiven) / (Cgiven - Cdes)
----- Original Message -----
From: "W7RIS" <email@example.com>
To: "'Ward Silver'" <firstname.lastname@example.org>; "'Towertalk Reflector'"
Sent: Friday, April 08, 2011 3:48 PM
Subject: RE: [TowerTalk] I.C.E. Vendors
> There are 7 capacitors required to build this kit. Yes DigiKey lists the
> parts but half of the capacitors required for the kit show '0' stock and
> none on backorder. This includes looking for substitutes of any voltage or
> tolerance. I know back 10+ years ago I didn't have any problems finding
> these parts. But not so in today's economy.
> I still stand with my original conclusion; the parts need to build the
> unit does not seem to be readably available at this time.
> Mike - W7RIS
> -----Original Message-----
> From: email@example.com
> [mailto:firstname.lastname@example.org] On Behalf Of Ward Silver
> Sent: Friday, April 01, 2011 11:08 AM
> To: W7RIS@ARRL.NET; 'Towertalk Reflector'
> Subject: Re: [TowerTalk] I.C.E. Vendors
> All of the specified values are available and appear to be in stock:
> I don't know if W3NQN changed the values from an earlier version but take
> another look. Good luck!
> 73, Ward N0AX
> ----- Original Message -----
> From: "W7RIS" <email@example.com>
> To: "'Ward Silver'" <firstname.lastname@example.org>; "'Towertalk Reflector'"
> Sent: Friday, April 01, 2011 12:49 PM
> Subject: RE: [TowerTalk] I.C.E. Vendors
>> We looked at the BCB Filter in the ARRL Handbook. The problem is when we
>> tried to find the parts to build one of these units. Looking at DigiKey
>> other parts retailer. We could only find about half of the required
>> capacitors. Even trying to put multiple capacitors in parallel, we still
>> could not come up with the right values.
>> My conclusion is, the parts needed to build the ARRL unit does not seem
>> be readably available at this time.
>> Mike - W7RIS
>> -----Original Message-----
>> From: email@example.com
>> [mailto:firstname.lastname@example.org] On Behalf Of Ward Silver
>> Sent: Friday, April 01, 2011 10:32 AM
>> To: Towertalk Reflector
>> Subject: Re: [TowerTalk] I.C.E. Vendors
>> All recent Handbooks also have the W3NQN BC Band Reject filter design in
>> RF and AF Filters chapter. (pp 11.44-45 in the 2011 edition) The filter
>> also be built with air-wound coils in a larger enclosure.
>> 73, Ward N0AX
>>> Call Bob, W5OV at Array Solutions.
>>> They have a W3NQN BCB reject - high pass filter that cures the RX BCI
>>> Tim K3LR
>>>> I hope this is not too far off the venue but can anyone assist me on
>>>> that carry I.C.E. filters...I am dead in the water on 160 due to BCI
>> TowerTalk mailing list
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