Building tips

To:
From: "Tony Parks"
Subject: Re: [softrock40] rxtx question - Transformers

Hi Paul,

The transformers need to be wound as specified on the schematic with the number of turns and core type as given in each case. The transformers have been a problem for a number of kit builders but I am at a loss to make the mounting instructions more clear than stated in the builder's notes. Please let me know if the builder's notes did not give the information that is needed to properly mount the transformers?

In winding transformers T2 and T3 care needs to be exercised to keep from scraping off the enamel insulation of the wire on the hard material of the binocular core. Before a transformer is mounted to the board an ohmmeter check needs to be done to identify lead pairs and to make sure there are no shorts between windings. Also, the kit builder needs to keep track of which is the single winding and which windings are the bifilar windings. Cutting the transformer leads to various lengths helps in getting each lead directed into its proper hole. Also the lead lengths can be used as a key to identify lead pairs after the pairs are first determined with an ohmmeter. Only strip and tin each transformer lead in the region of the wire that will be soldered to the circuit board.

Low RF output and no sideband suppression can be associated with improper mounting of T1 to the circuit board.

73,

Tony KB9YIG

Wiring the exciter

To: softrock40@yahoogroups.com
From: "kb9yig"
Subject: [softrock40] Push to talk or key input in a simple SDR transceiver

Good Morning,

The question comes up how to signal from a simple SDR transceiver to
the PC (SDR program) that it is time to produce I/Q output on the
line-out for generation of transmit output. One way is to have a
parallel or serial port connection from the PC to the transceiver
but, that adds another cable into the system and possible additional
noise with both digital and soundcard grounds coming to the
transceiver.

Here is a suggestion for signaling to the PC that requires only the
line-in and line-out cables between the PC and the transceiver. To
work, it requires a hardware means of muting the line-in signal from
the transceiver such as the QSD enable line on the v6.0 SoftRock.

During receive, the exciter portion of the transceiver is enabled
and connected to the receive antenna. The line-out from the
soundcard is used to provide one channel for receive audio output to
the speaker or headphones and a second channel to the QSE circuit
audio input. During receive the SDR program generates a continuous
low level signal on the second channel of the line-out so that a
double sideband signal is produced by the QSE in the receiver
spectrum. The frequency of the tone from the soundcard would be
such that the extra signal in the received spectrum is well removed
from the currently selected receive frequency. When the QSD is
disabled by a hardware means, (push to talk or key down event), the
extra signal stops and the SDR program recognizes the event. Push
to talk or key down would, by hardware means, do the T/R switching
at the transceiver and mute the received audio output to the speaker
or earphones. (For CW operation a side-tone signal would be
connected to the speaker output.)

An open question is would the SDR program be able to respond quickly
enough to support high speed CW.

73,
Tony KB9YIG

To:
From: "Tony Parks"
Subject: Re: [softrock40] Re: Wiring a Key or PTT button to the SoftRock RxTx

Hi Terry,

The interface below is also what Alex is using with Rocky. Pin 6 is Dot and pin 8 is dash.
Pin 3 is the supply pin for pullup resistors to pins 6 and 8. Rocky works very nicely this way
with just a couple resistors and capacitors at the serial connector.

73,
Tony KB9YIG

----- Original Message -----
From: Terry
To: softrock40@yahoogroups.com
Sent: Monday, March 12, 2007 6:05 PM
Subject: [softrock40] Re: PowerSDR-sr40 v1.9.0 Release

I have been using PowerSDR V1.6.3 as modified by Bill Tracey for the
SoftRocks, from October of last year. His connections were:
Pin 5, GND for PTT to RxTx
Pin 7 (RTS) for PTT switching to RxTx
Pin 4 (DTR) is common out keyer paddles
Pin 6 (DSR) is one keyer paddle in (dot/dash, don't remember which)
Pin 8 (CTS) is other keyer paddle in (dot/dash, don't remember which)

If I remember correctly, this pinout came from an even earlier
source, but I cannot find it offhand. I used the above for the
prototype RxTx testing I was doing last year.
Terry

Band Coverage

To: softrock40@yahoogroups.com
From: "kb9yig"
Subject: [softrock40] SoftRock v6.0 - 80m / 40m operation

Several have been concerned about the SoftRock v6.0 idea of selecting
between two harmonically related bands such as 80m and 40m by only
changing the clock divide ratio. The divide ratio would be divide by
four for 40m and divide by eight for 80m. The BPF would be made board
enough to span the two bands. The concern was that strong 40m signals
would be in the 80m spectrum when 80m operation was selected.

I have been observing the 40m and 80m operation this evening with the
first of the v6.0 SoftRock receiver examples. I find that even 20
over S9 signals on 40m do not appear in the spectrum when 80m
operation is selected. I believe this suggests good balance in the
v6.0 QSD circuit.

I am happy to report that it looks like two band operation, at least
for 80m and 40m, results in good receiver operation. Bill, KD5TFD,
will be evaluating the performance of the first prototype next week
and will post measurement numbers on MDS, dynamic range and
40m "leakage" to 80m at large signal levels.

The eight first responders to the v6.0 prototype kit announcement have
been sent e-mail offers to receive a prototype kit. That will be all
the prototype kits I will have to send out.

Good chance that I will be in a position to start shipping production
kits by the end of March if the prototype evaluation goes well.

Thanks and 73,
Tony KB9YIG

To:
From: "Tony Parks"
Subject: Re: [softrock40] softrock V6 on 20M

Hi Ray,

The problem with the v6.0 SoftRock getting to 20m is the need for a
fundamental crystal 4x times the center frequency you want on 20m. Another
way to get to 20m is with 3rd sub-harmonic sampling. The crystal frequency
then needs to be (14.24/3)*4 = 18.987 MHz . The BPF needs to be for 20m and
probably with a more narrow response than the BPF in the v5.0. The
sensitivity of the v6.0 used this way will be down 6 dB but I think it
should still be as sensitive as the v5.0 on 20m. Worth a try anyway, I
think.

73,
Tony KB9YIG




To:
From: "Tony Parks"
Subject: [softrock40] 17m SoftRock Lite info

Hi Loren,

I tried sending the message below this morning only to have is bounce back, thus the posting
to the Yahoo group.

I looked at the 17m SoftRock Lite filter this morning and reasonable
component changes would be to leave L1 and T1 winding turns the same as the
20m SoftRock Lite (T25-6 cores, yellow) and change the BPF capacitors to be
C21=33pF, C22=470pF. The capacitors in the oscillator circuit, C3 and C4,
can stay the same as the 20m SoftRock Lite. R6 might be needed depending on
the crystal activity.

Hope this helps.

73,
Tony KB9YIG

To:
From: "Tony Parks"
Subject: Re: [softrock40] Softrock on 5MHz

Hi Roger,

Here are a set of component values that should be ok for the SoftRock Lite on 5 MHz.

L1 43T of #30 on a T25-2core (6.3 uH)
T1 10T of #30 on primary and 5T of #30 in each of the two secondary
windings "bifilar" over the top of the primary on a T25-2 core (0.35 uH on primary)
C21 150 pF
C22 2200 pF

73,

Tony KB9YIG

General Information

To:
From: "Tony Parks"
Subject: Re: [softrock40] Softrock light dimensions

The SoftRock Lite board is 1.5 inches by 1.5 inches with two mounting holes located at (0.75, 0.1) and (0.75, 1.4) from the lower left corner of the board, (x,y) in inches. The height of a built board is about 0.75 inches which includes the height of the 0.125 inch board mounting spacers.

73,
Tony KB9YIG

To:
From: "Tony Parks"
Subject: Re: [softrock40] Receiver active while transmitting

Hi Ian,

Rocky RX function stays active during TX so even though the QSD circuit is muted during TX there is enough "stuff" that gets through to the sound card line-in inputs to cause spikes on the spectum display. This happens even when power is turned off to the board. It would be more pleasing if the spectrum display held the last RX spectrum view when in TX but for now one needs to ignore what shows on the spectrum display during TX.

All that said, it is possible to enable the QSD circuit during TX by grounding pins 1 and 15 of U7 at their common connection to R42. By then setting the TX transmit level at a very low level, -30dB or so, the transmit spectrum can be displayed. The unwanted sideband null may be done this way. An independent measure of the unwanted sideband with another receiver when at full output is a good check to make sure the unwanted sideband is really down 50 dB or more.

73,
Tony KB9YIG

The SoftRock doing IF duty

To:
From: "Tony Parks"
Subject: Re: [softrock40] Re: SoftRock V6 as an IF for a TS-520S?

Hi Dick,

Actually since the v6.0 will have a lot more gain than needed in the IF
application you could go with your crystal oscillating at 9021.666 kHz and
use sub-harmonic sampling. Set the JP1 jumper plug to divide by 8 for a QSD
center frequency of 1128 kHz, 1/3 of the desired center frequency of 3383
kHz. The BPF needs to be selective at the IF frequency to reject unwanted
signals such as AM broadcast. Hope I am not thinking wrongly about it, buit
I think it would work as you want it to.

73,
Tony KB9YIG

To:
From: "Tony Parks"
Subject: Re: [softrock40] Building a softrock 6 Rx into a rig SoftRock on 10.7MHz IF

Hi Richard,

A SoftRock with a 14.4 MHz crystal would give a 1/3 sub-harmonic sampled center frequency of about 10.799 MHz which might be about right for your 10.81 MHz IF signal. The 14.4 MHz crystal is a low cost SMT crystal and I have a few in stock. I can provide a SoftRock Lite kit with the 10.8 MHz BPF and the 14.4 MHz crystal for $13 which includes the postage to the UK.

73,
Tony KB9YIG




To:
From: "Tony Parks"
Subject: Re: [softrock40] Elecraft K3 and SoftRock

A SoftRock Lite for K3 use could have a center frequency of about 8.191 MHz by use of a low-cost 32.768 MHz crystal. This would place the center frequency about 24 kHz below the center of the K3's IF passband and when used with a soundcard that can sample at 96 kHz the view of signals in the IF passband would be about +/-24 kHz from the center of the K3 passband without the SoftRock center frequency noise being in the picture. The gain of the K3 SoftRock Lite kit could be set for the signal level available from the K3 IF output.

Thanks and 73,
Tony KB9YIG

Problems

Work in progress.

Recommended Cards

Work in progress.