[Lowfer] First Impressions: AMRAD Converter and Lowpass Filter

[riese-k3djc at juno.com]

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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