Re: [softrock40] Re: v6 v6 RXTX info 11/01
- Hi Chris,Yes, the low output problem has also been noted by a number of kit builders of the prototype three board stack. The change will work for either the three board stack or the single board RXTX.73,Tony KB9YIG----- Original Message -----From: Christopher T. DaySent: Wednesday, November 01, 2006 5:14 PMSubject: RE: [softrock40] Re: v6 v6 RXTX info 11/01
Ive been out of touch for awhile and have lost track. Does this low power PA problem also occur with the TX stack version? Thats the kit I have, but have not started it yet. Thanks.
From: Terry [mailto:wb4jfi@ knology.net]
Sent: Wednesday, November 01, 2006 1:52 PM
To: softrock40@yahoogro ups.com
Subject: [softrock40] Re: v6 v6 RXTX info 11/01
From Terry, WB4JFI:
As Tony says below, it appears he has fixed the low-power issue with
the PA. It has taken me longer than I thought to clean my board up
(I had messed with it a LOT to do the testing). Plus, I had to run
some errands and get a flu shot this afternoon.
I haven't put the driver and QSE circuits back together yet, but in
testing the PA with a signal generator for input signal, and scope
and spectrum analyzer on output, the final stage appears
significantly cleaner. I plan to do some testing here and get actual
measurements before putting the drive and QSE back together.
I would suggest that those of you who want to go ahead and put your
boards together can do everything except the PA and output filter.
The PA may have some bias component adjustments, and the output LP
filter appears to peak at 6.8MHz. If you wnat to build and test the
receiver portion, you can either build the filter as shown, or bypass
if for now, recognizing that you will need to change the parts for
final operation. If you want to build the existing LP filter, I
suggest you take one turn off both L4 and L5. Then the filter peaks
So far, Tony's modifications are looking good. I'm sure he will let
everyone know what needs to be done once we complete testing.
--- In softrock40@yahoogro ups.com, "kb9yig" <raparks@... > wrote:
> Good Afternoon All,
> As of this morning all v6 RXTX kits have now been mailed. Please
> check your kit and let me know if there are missing or broken
> parts. I will send needed parts as soon as possible.
> Testing continues with a number of the RXTX kits built. A number
> builders have experienced low output and poor effieciency in the PA
> circuit. This morning I was able to make a few component changes
> that resulted in a very clean looking sinewave output to a 50 ohm
> load with slightly more than 400mW output. Moreover the center
> frequency signal with no audio input to the board was measured at
> dB below full output. The circuit changes are also being made by
> Terry Fox this afternoon and he will check output power, center
> frequency output, harmonic output and sideband suppression.
> When /if the above component changes are proven to be a good
> solution, then I will be sending out a small kit of parts to each
> alpha and beta kit buyer. Since over 100 mailing are involved, it
> would be very helpful if all kit buyers could check their kit
> contents and let me know if other parts are also needing to be sent.
> Thnaks and 73,
> Tony KB9YIG