[Lowfer] First Impressions: AMRAD Converter and Lowpass Filter

Wed Feb 4 20:50:55 EST 2015

Bob: Perhaps the RAY6

    https://www.dropbox.com/s/2aiv7qqsx1ppr8r/RAY-6.pdf?dl=0

    Pull the contents divider to the left with the "handle" and the pdf will 
expand....

    I have one paired up with a 3.0MHz Isotemp OCXO. A 3dB pad on the OCXO 
output to a single-ended
25109 Norton amplifier to provide +22 dBm LO power.  DBM input driven with 
the W1VD design 2N5109 VLF pre-amp.

    LPF before the preamp is a 9th order Butterworth with 300 kHz cutoff....

    https://www.dropbox.com/s/wrrqg2rsa3a2aha/300kbtw3.jpg?dl=0  which 
performs essentially as the model predicts....

    3.3 MHz diplexer on the output side of the RAY6 courtesy the VE7BPO 
diplexer program....

    https://www.dropbox.com/s/l79sv0zpsspckyd/zoidip1.jpg?dl=0

    And I scaled the W1VD 500kHz preselector to 3.2~3.5 MHz as my IF radios 
lack roofing filters....

    https://www.dropbox.com/s/a6mx485qcn7nk3a/RAY6BPF.JPG?dl=0   I have it 
peaked up for 3475 kHz and use it at lower IF frequencies (down to 3200kHz) 
for

   casual NDB listening....

   I'm reasonably happy with how it performs.....

    73, Mike wa3tts

----- Original Message ----- 
From: <riese-k3djc at juno.com>
To: <lowfer at mailman.qth.net>
Sent: Wednesday, February 04, 2015 8:15 PM
Subject: Re: [Lowfer] First Impressions: AMRAD Converter and Lowpass Filter

>
> Many years ago I built a converter using a mini circuit DBM that was
> specked
> to LF and handled strong signals well,,, dont remember which one, there
> were many
> fed it with a clock osc at 4 Mhz which was
> spot on and drift free  ? Not sure how that happened?
> fed it with a LF eng preamp and had a very good LF convertor
> then the York Hosp went to switching power supples for there elevators
> and that has pretty much shut me down
> but the DBM made a very good convertor and super simple to get working
> It wanted a 50 Ohm in for the LO and I built some sorrt of pad which cost
> me
> some of the LO signal but it never overloaded,,, so it made me happy
> fun stuff
>
> Bob K3DJC
>
>
>
> 0500 <jrusgrove at comcast.net> writes:
>> That said...I'm not exactly sure what performance parameters I'd be
>> looking to compare.
>>
>> The usual tests ... same as for a receiver ... MDS, 1-dB
>> compression, 2-tone IMD and phase noise.
>>
>> Jay W1VD  WD2XNS  WE2XGR/2
>>
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Ben Hall" <kd5byb at gmail.com>
>> To: <lowfer at mailman.qth.net>
>> Sent: Wednesday, February 04, 2015 4:59 PM
>> Subject: Re: [Lowfer] First Impressions: AMRAD Converter and Lowpass
>> Filter
>>
>>
>> > On 2/4/2015 2:08 PM, Douglas D. Williams wrote:
>> >> Hi Ben. Looks like JD and Zack got your 530 kHz situation sorted
>> out.
>> >
>> > Absolutely.  I wanted to play with the converter again last night
>> but
>> > just did not get around to it.
>> >
>> >> Given my correspondence with Todd, I would advise replacing that
>> RG174
>> >> between your LPF and converter. If you do have some spare
>> LMR-195, that
>> >> would be ideal, IMO.
>> >
>> > Even better - I found some LMR-240 and appropriate connectors.  I
>> should
>> > be able to install it this evening.  I'll probably replace the
>> RG-174
>> > that delivers the 3 MHz from the OCXO as well.
>> >
>> >> I happen to have a spare Todd Roberts converter. Would be
>> interested to see
>> >> if anyone would be interested in doing some performance
>> measurements
>> >> comparing the IC that Ben used with the original AMRAD IC.
>> >
>> > I have at least one more of my custom printed circuit boards for
>> the
>> > converter.  I have thought about building a second converter using
>> the
>> > SOIC variant of the 74HC4053 chip so I could compare it with the
>> > 74LVX4053 version.
>> >
>> > That said...I'm not exactly sure what performance parameters I'd
>> be
>> > looking to compare.  If folks could suggest some tests/test
>> setups, I'll
>> > see if I've got access to the equipment I need to conduct them and
>> build
>> > up the second unit with the 74HC4053.
>> >
>> > thanks much and 73,
>> > ben, kd5byb
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