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

[pat bunn]

-------- 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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