I've built these filters (10 in all) using the high voltage ceramic caps
available
at Allied (yes, they still exist). http://www.alliedelec.com/
Using 1KV NPO/N750 , the tolerances are +/- .5pf for the smaller values,
+/-5% for 10pf and up (they range from 1.0 to 680pf). Yes, you'll have to
series/parallel them get the voltage ratings you want.
They have also 3kV , 6KV, and 10KV caps. at +/- 20%.
cheers
dink, n7wa
On 4/9/2011 7:31 AM, Ward Silver wrote:
> 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
> in-stock.
> - 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
> combinations, too*
>
> 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"<w7ris.arrl@softgoals.com>
> To: "'Ward Silver'"<hwardsil@gmail.com>; "'Towertalk Reflector'"
> <towertalk@contesting.com>
> 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
>> ARRL
>> unit does not seem to be readably available at this time.
>>
>> Mike - W7RIS
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] 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:
>>
>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=131088&k=polypropyl
>> ene%20capacitor
>>
>> 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"<w7ris.arrl@softgoals.com>
>> To: "'Ward Silver'"<hwardsil@gmail.com>; "'Towertalk Reflector'"
>> <towertalk@contesting.com>
>> 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
>>> and
>>> 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
>>> to
>>> be readably available at this time.
>>>
>>> Mike - W7RIS
>>>
>>> -----Original Message-----
>>> From: towertalk-bounces@contesting.com
>>> [mailto:towertalk-bounces@contesting.com] 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
>>> the
>>> RF and AF Filters chapter. (pp 11.44-45 in the 2011 edition) The filter
>>> can
>>> 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
>>>>
>>>> 73,
>>>> Tim K3LR
>>>>
>>>>> I hope this is not too far off the venue but can anyone assist me on
>>> Vendors
>>>>> that carry I.C.E. filters...I am dead in the water on 160 due to BCI
>>> ...tnx
>>>>> Dick..W4NTG
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>> _______________________________________________
>>
>>
>>
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