[600MRG] Fwd: Re: Testing new Transmit downconverter

[Edward R Cole]

Dave,

This is the mixing approach I favor as one can utilize high precision 
10-MHz references as the LO.  However the IF radio has to be capable 
of transmitting on 10.470-10.480 MHz.  This is outside the amateur 
30m band.  The K3 is able to run there with no issue, but might be 
challenging for other radios (without modification).

I have the K3's little brother, the KX3.  But it is not as versatile 
and also does not exhibit as good frequency stability.  I understand 
an external reference ckt is under consideration at Elecraft which 
may fix that.  Still one might have to design a transverter that 
utilizes a standard ham band as IF.  This may require finding an 
adequate oven controlled oscillator to provide a super-stable LO.  A 
TCXO at 3.0 MHz with 0.5-ppm might suffice (3000 kHz x 0.5 E-6 = 1.5-Hz).

73, Ed - KL7UW

At 04:50 PM 4/25/2013, Dave wrote:
>I built a true transverter (ie tx and rx converter) for 474.2khz in my uk
>station and I have been very pleased with it
>
>I use the k3 as the IF at 30m and use the K3 10MHz reference as the local
>oscillator
>
>I did use it for a while with a good 10MHz oscillator as the LO and still
>got decodes
>
>To reduce the size of the LF station I have used the FT817 as the IF on 30m,
>but mine definitely needed the onboard histab oscillator to get reliable
>decodes
>
>Dave
>
>Ww2r, g4fre
>
>-----Original Message-----
>From: 600MRG [mailto:600mrg-bounces at w7ekb.com] On Behalf Of pat bunn
>Sent: Thursday, April 25, 2013 8:57 AM
>To: 600MRG at w7ekb.com
>Subject: [600MRG] Fwd: Re: Testing new Transmit downconverter
>
>
>
>
>-------- Original Message --------
>Subject:        Re: [600MRG] Testing new Transmit downconverter
>Date:   Thu, 25 Apr 2013 09:45:53 -0400
>From:   pat bunn <pbunn at patbunn.com>
>To:     John Langridge <jlangridge at sbcglobal.net>
>
>
>
>My experience with transmitting down converters is not all that good -
>actually bad. They are easy to make from scratch, but the problem is
>with stability in the transmitter or transceiver. I found my IC718 to be
>worthless for WSPR, especially WSPR-15 even at 1 watt output due to
>thermal heating causing significant frequency drift. I think Dex also
>had the same problem with a newer ICOM tranceiver.  The IC718 set at one
>watt out got physically hot to touch after a 15 minute WSPR transmission
>and was impossible to decode by Dex,  80 miles away( a very strong
>signal) due to drift
>
>They are probably fine for CW, but for long QRSS or other long transmit
>modes, you are likely to be disappointed.
>
>After testing several different methods to stabilize the transceiver, I
>bought a used HP signal generator to generate my transmit signal to feed
>the class D Amps. I have this GPS disciplined and am very happy with
>this solution.
>
>
>Pat
>WG2XCT
>N4LTA
>
>
>
>
>
>
>On 4/24/2013 8:47 PM, John Langridge wrote:
> > First of all, let me say thanks to all of the stations that continue to
>listen
> > and transmit on 630m as the days seem to get longer at an alarming rate
>and
> > noise keeps going up.  The last month has been brutal here in NTX but the
>last
> > few nights have shown some improvements.  Thanks again!
> >
> > Tonight I am testing a new transmit down converter developed and kitted by
>John
> > Molnar, WA3ETD/WG2XKA.  The kit is pretty sweet, with a minimum of parts
>and
> > appears to be capable of producing close to 20 watts using an IRF510 at
>13.6v
> > and around 2 amps.
> >
> > SO far I really like what I am seeing.  Anyway, I will be testing it
>tonight but
> > plan on letting it run in some capacity over night, whether as exciter
>only or
> > driving the amp, I have not yet decided.
> >
> > 73 and again, thanks for listening!
> >
> > John KB5NJD/WG2XIQ
> > _______________________________________________
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> >
>
>
>
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