[Hammarlund] [National] [Boatanchors] Collins 3.1 KC filterquestion

Thu Sep 13 16:42:18 EDT 2012

I have both the miniature 7 pin, and octal base Collins plugin
mechanical filter adapters here and the Collins documentation for
each. Type 353B-31, 7 pin base, and the 353A-31 with the octal base.
Both with a Collins 3.1kc mech filter inside.
The 353B could be used with the Hammarlund SP-600 receiver and it
physically fits right in between the IF cans in that rx.

I don't know about that MFA part number.

Al VE3AJM

On 9/13/12, Brian Harris <cosmophone at yahoo.com> wrote:
> My thanks to all that have replied.  This unit has a Collins p/n marked and
> it fits either a 7 or 9 pin miniature.  I'll find out which later today and
> get pictures too.  I'm going to guess it's for an SP-600 since it has the
> Hammarlund designation too.  I'll get it from my friend in California and
> try it out in one of my SP-600's some day but before I plug it in I'll check
> out the circuitry to be sure it matches that of the 600.
>
>
> Brian Harris
> cell 214-763-5977
> email cosmophone at yahoo.com
>
>
> ________________________________
>  From: Richard Knoppow <1oldlens1 at ix.netcom.com>
> To: Carl <km1h at jeremy.mv.com>; National Radio Equipment
> <national at mailman.qth.net>; kgordon2006 at frontier.com
> Cc: National Radio Equipment <national at mailman.qth.net>;
> Hammarlund at mailman.qth.net
> Sent: Thursday, September 13, 2012 2:52 PM
> Subject: Re: [National] [Hammarlund] [Boatanchors] Collins 3.1 KC
> filterquestion
>
>
> ----- Original Message -----
> From: "Carl" <km1h at jeremy.mv.com>
> To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>; "National
> Radio Equipment" <national at mailman.qth.net>;
> <kgordon2006 at frontier.com>
> Cc: "National Radio Equipment" <national at mailman.qth.net>;
> <Hammarlund at mailman.qth.net>
> Sent: Thursday, September 13, 2012 11:24 AM
> Subject: Re: [National] [Hammarlund] [Boatanchors] Collins
> 3.1 KC filterquestion
>
>
>>
>> ----- Original Message -----
>> From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
>> To: <kgordon2006 at frontier.com>
>> Cc: "National Radio Equipment" <national at mailman.qth.net>;
>> <Hammarlund at mailman.qth.net>
>> Sent: Thursday, September 13, 2012 1:36 PM
>> Subject: Re: [National] [Hammarlund] [Boatanchors] Collins
>> 3.1 KC filterquestion
>>
>>
>>>
>>> ----- Original Message -----
>>> From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
>>> To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
>>> Cc: <Hammarlund at mailman.qth.net>; "National Radio
>>> Equipment"
>>> <national at mailman.qth.net>
>>> Sent: Thursday, September 13, 2012 10:08 AM
>>> Subject: Re: [Hammarlund] [Boatanchors] Collins 3.1 KC
>>> filter question
>>>
>>>
>>>> On 13 Sep 2012 at 8:52, Richard Knoppow wrote:
>>>>
>>>>> Good Morning All,
>>>>>
>>>>> Collins made a filter for Hammarlund which is
>>>>> designated
>>>>> "MFA-3 3.1 KC filter". Does anyone know which piece of
>>>>> Hammarlund equipment this was for? Google was not my
>>>>> friend
>>>>> in this inquiry.
>>>>
>>>> I have seen advertisments, and examples for sale on
>>>> eBay,
>>>> of such filters which were made
>>>> for Hammarlund receivers, HRO receivers, and for others.
>>>>
>>>> I cannot now remember which companies offered those for
>>>> sale, but I am reasonably certain
>>>> Collins was one of the companies involved.
>>>>
>>>> These were complete units containing a Collins filter
>>>> and
>>>> two tubes. The unit was mounted
>>>> on an octal socket so that all that was required was to
>>>> unplug the 1st 455 KHz IF tube, and
>>>> plug this in place of the tube. No other changes were
>>>> made
>>>> to the receiver.
>>>>
>>>> Those very few I have seen on eBay went for prices
>>>> comparable to that for an entire receiver.
>>>>
>>>> I also have an article from a GE Ham News detailing
>>>> exactly how to make those units. I
>>>> suspect that this GE Ham News article preceded the
>>>> offering by Collins and others.
>>>>
>>>> Go here:
>>>>
>>>> http://www.w7ekb.com/glowbugs/rx/receivers.htm
>>>>
>>>> then scroll down to 5) Packaged Selectivity.
>>>>
>>>> There are a number of PDFs offered there: one is the
>>>> complete article, the others are
>>>> individual pages since the complete article consists of
>>>> a
>>>> quite-large file and would take some
>>>> time to download without a high-speed internet
>>>> connection.
>>>>
>>>> Ken Gordon W7EKB
>>>
>>>      The difference may have been in the plug.  The
>>> SP-600
>>> uses 6BA6 tubes in the IF which are 7-pin miniatures
>>> while
>>> the SP-400 and 200 and the HRO use octal-based tubes.
>>> There
>>> are probably other differences to account for mechanical
>>> clearances.
>>>
>>>
>>> --
>>> Richard Knoppow
>>> Los Angeles
>>> WB6KBL
>>> dickburk at ix.netcom.com
>>
>>
>> The SP-200 IF is 465 KHz and predated and was out of
>> production before Collins mechanical filter release by
>> several years. The only early Hammarlund interest was in
>> the Zenith design.
>>
>> Post WW2 adaptors were only available for the SP-400,
>> HRO-60, and later the NC-400 which was not a Collins built
>> assembly.
>>
>> Carl
>> KM1H
>>
>      You are quite right, the IF frequency was different.  I
> wish I could find the ad I remember.  I think these adapters
> were made by some third party, not Hammarlund, National or
> Collins.  Have you seen any and do you know who made them?
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
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