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

[pat bunn]

-------- Original Message --------
Subject: 	Re: [600MRG] Testing new Transmit downconverter
Date: 	Thu, 25 Apr 2013 11:56:15 -0400
From: 	pat bunn <pbunn at patbunn.com>
To: 	John Langridge <jlangridge at sbcglobal.net>



John,

The one that I built worked flawlessly also - That was not my point - 
The stability is in the transceiver driving the transverter - Most 
transceivers are not frequency stable enough in transmit mode to work 
with slow mode transmitting. They get hot and drift a few cycles.

If you can find a transceiver that will be stable during long 10-15 
minute transmit cycles, you will have no problem.

Pat


On 4/25/2013 10:06 AM, John Langridge wrote:
> Hey Pat - sorry to hear about you experience.  The one I built based 
> on the G3XBM-design driving the GW3UEP amp worked flawlessly through 
> the 2012/2013 season and continues to function pretty stable even 
> using a 3.2 rock for an LO.
>
> For CW I use a homebrew VFO and separate amp but could use the 
> transverter with good success.  I just hate dealing with the offset 
> that the radio automatically applies to the carrier freq which is why 
> I prefer the home brew VFO.
>
> John Molnar's board is very unique in that it has an option for and 
> out board 10 MHz GPS locked LO instead of the crystal.  That is 
> something I will look at going forward. The board seems to do well and 
> is good value for someone who may be new to putting kits together and 
> wants to get on the band.  I give it a thumbs up so far and I am doing 
> some tweeking this morning to make sure I got the toroids wound 
> properly.  My original downconverter does not use toroids but had 
> equal adjustments that had to be made to make sure I was getting max 
> power and best wave form.. Too bad we can't just wind them and put 
> them in HI!
>
> thanks for the comments.  SO far I like what I see on the board XKA 
> designed.  Its certainly much easier than the dad bug design I used 
> for the original box!
>
> 73 and looking for you in the noise!
>
> John /NJD/XIQ
>
> ------------------------------------------------------------------------
> *From:* pat bunn <pbunn at patbunn.com>
> *To:* John Langridge <jlangridge at sbcglobal.net>
> *Sent:* Thu, April 25, 2013 8:45:59 AM
> *Subject:* Re: [600MRG] Testing new Transmit downconverter
>
> 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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>