----- Original Message -----
From: "Roger" <sub1@rogerhalstead.com>
Cc: <amps@contesting.com>
Sent: Tuesday, December 23, 2008 4:59 PM
Subject: Re: [Amps] [rfamplifiers] which cathode choke?
>
>
> Carl wrote:
>> That sounds like the old Radiokit 30A choke kit. It worked well down
>> to 160M with a single 4-1000A
>>
> I think I built them just shortly before the kit came out. If memory
> serves correctly I purchased a dozen of the rods, but I don't remember
> where I purchased the enameled #10. There were a lot more sources back
> in the 60's. <sigh>
>
> 73
>
> Roger (K8RI)
>> Carl
>> KM1H
Ive still got plenty of the rods and #10 or #12. Thinking seriously
about firing up Radiokit again primarily for amp building now that Ive
got the time and no more 9-5 job.
Still have most of the old vendor contacts.
Carl
KM1H
>>
>>
>> ----- Original Message ----- From: "Roger" <sub1@rogerhalstead.com>
>> Cc: <amps@contesting.com>
>> Sent: Tuesday, December 23, 2008 12:15 AM
>> Subject: Re: [Amps] [rfamplifiers] which cathode choke?
>>
>>
>>>
>>>
>>> jeremy-ge wrote:
>>>> Id lean to the B&W, it gives you almost 500 Ohms Xl at 160 which is
>>>> OK.
>>>> Bypass the filament transformer end with .05 to .1 uF discaps. Ive
>>>> no
>>>> idea what the MFJ's intended use is.
>>>>
>>> "Back in the old day", I wound a number of them on ferrite rods. I
>>> only
>>> remember the approximation of size but it seems as if the specs were
>>> in
>>> one of the handbooks. The rod was between 1/2 and 5/8" in diameter
>>> and
>>> about 6" long. The winding was close spaced, bifilar wound using
>>> #10
>>> enameled wire. One would handle a pair of 3-500's or 8877. I had a
>>> bunch
>>> of them but they and a lot of other stuff went when I did the first
>>> thorough clean out of "stuff I'll probably never use". I wish I had
>>> all
>>> that *stuff* back.
>>>
>>> At any rate, the chokes were easy to wind, worked well, cost
>>> little,
>>> and looked good. I say they worked well. They was 80 through 10. I
>>> never tried one on 160 and I don't remember the impedance.
>>>> The homebrew will work also but you will have to keep an eye on the
>>>> voltage drop.
>>>>
>>> I used one of the above on a pair of 813's with the voltage
>>> remaining
>>> well with in spec. Too bad it was so long ago that I don't remember
>>> any
>>> specifics.
>>>
>>> 73
>>>
>>> Roger (K8RI)
>>>> Carl
>>>> KM1H
>>>>
>>>> ----- Original Message ----- From: "Steve Flood"
>>>> <kk7uv@bresnan.net>
>>>> To: <rfamplifiers@yahoogroups.com>; <amps@contesting.com>
>>>> Sent: Sunday, December 21, 2008 8:19 AM
>>>> Subject: [rfamplifiers] which cathode choke?
>>>>
>>>>
>>>> I have three different bifilar wound ferrite rod chokes.
>>>>
>>>> A homebrew choke measuring 127uH
>>>> A B&W FC-25A measuring 44uH.
>>>> An Ameritron/MFJ #10-15115-1 measuring 19uH.
>>>> The measurements were taken on one winding with an Elenco LCR
>>>> meter.
>>>>
>>>> Which one would best for grounded-grid 813's operating 160m thru
>>>> 20m?
>>>>
>>>> Thanks, Steve KK7UV
>>>>
>>>> _______________________________________________
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>>>> http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>>
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>>
>>
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