Wednesday, 25 November 2009

MOBO & V6.3 SR and FT243 crystals

http://sites.google.com/site/lofturj/mobo4_3

OK Art and Alex pulled the stops out and managed to scrounge together a full kit of parts for me. So I'll be building this asap. However, it is a bit like buses you wait to ages and two come along at once and the same with work so that has taken over in the last week so not apparently done much. I will be building as I did in HB9during 2007 and I will have the mobile /P homebrew bench in a airline carry on bag and build in the hotel room in the evening.... This should be interesting. Just spoke to Simon HB9DRV and his new SDR software http://www.sdr-radio.com is not far away from release including support for USB controlled Si570 Softrocks. The MOBO we will both eargerly be waiting to see the usb sound card add on too the current beta kit is without that.

Also one kind soul sent me a pile of 80m crystals after the GQRP valve day and I will add those to the 6V6 TX this w/e and also 'put up something horizontal' so inter G working is possible.

Wednesday, 18 November 2009

Cat in the shack

You have to be a cat person or have experienced cat behaviour to get the funny side of this but in my shack I have one of those angle lamps with a magnifying lens and when I am in the shack the cat tends to come in and occupy either the operating seat or the homebrew bench seat... anyway this afternoon it decided the homebrew bench, on the PCB I had under the lamp was a warmer place. I mentioned it to Dad and he sent me the link. Shame didn't have a camera but sure Pud will repeat it again soon...

Enjoy.

http://www.simonscat.com/hotspot.html

Tuesday, 17 November 2009

Softrock Si570 AVR/ USB firmware

As building the V6.3 and MOBO V4.3 and built 4 versions of the V9.0 already and gone through a few different firmware revisions I thought should mention an up to date reference (as of today anyway).

The original eons ago firmware, as far as software development life cycles are concerned anyway, that the V9.0 and V6.3 kits used to ship with works, with bugs but it is so old and out of sync with the up to date software developments going on you really do need to update the firmware on the AVR chips.

Wander over to http://home.ict.nl/~fredkrom/pe0fko/g8voi/ and peruse the documents on that page. It will explain everything.

The firmware you need can be obtained here:
http://home.ict.nl/~fredkrom/pe0fko/SR-V9-Si570/

He has made the source available here:
http://code.google.com/p/usbavrsi570/

I am not saying what you have as supplied by W&S or Tony Parks will not work just you should take on-board what G8VOI and PE0FKO say on the matter.

PCB source

I was asked by another UK amateur about my use of PCB for things if I had a friendly PCB source. The quote is "...just curious about what seemed to be extravagant usage – it was obvious that either you had deep pockets or an interesting story to tell"...

This is the story of how I got the PCB.

In May 2003 needed a few bits of PCB as I was trying to build a BLT. Maplin wanted what seemed like a huge amount for very little and I had heard mention there were some PCB fabrication places around Cambridge... so I found one... then in total innocence I went in to see them, this was back in 2003 just after I was licenced and asked if they had any 'off cuts' they could sell me. I even had my little bag of change out. The answer was not at that time but could I turn up, a couple days later, which I did on a bicycle with a pannier eagerly hoping might get enough as I was about to build that BLT so didn't need much! Anyway the bod who met me was one of the directors and he listened to what I wanted and why etc... (he wasn't an amateur). So that night he gave me 6 or 7 pieces for what I wanted as long as I showed him the end result which I was happy to do, I went back 2 weeks later with it and a desk pencil holder I had made with the other bits I had left over, I noticed the reception didn't have a place for the pens by the signing in book, so I made one and gave it to them. We bought each other a beer in a pub around the corner and I went off to operate /P for maybe the first time from the bicycle.... he said come back in a month, and he'd have some more bits, I could share with others .... but next time could I come in a car?

Anyway I turned up with help from a now SK G0 who had van and he gave me a (48 crisp packet sized) box of off cuts as he explained they go through >1,000 square feet of PCB in a good week, I had been given all the off cuts from the last few weeks production runs. Also he had a stack of sheets c2' x 4' that were not up to spec as the copper was ridged or non uniform, he asked if I wanted them... said yes obviously, he fed a dozen or so into an auto gulloteen (spelling?) and chopped into foot squares. I kept one sheet whole for the home brew bench. He said keep the cash as he would have had to pay to dispose of it all. However, he asked me not to reveal who/where I got it from and if I was to throw it out to contact hime first.

A local club when still a member I took the PCB sheets in one night and thought £1 a sheet to club funds seemed reasonable but hardly anyone interested so I took it home and I use/used it for making chassis. The next meeting I took the off cuts of PCB in and said were free needless to say 90% disappeared in minutes, now I realise that the dark stuff was mobile phone/wifi RF stuff. There was all sorts, single sided, double sided, thick and really thin stuff. I did the same thing the following year too.

That is how I have it and no don't have deep pockets.

This is the same place that also allows me to dispose of used etch solution.

Maybe ask your friendly PCB fabrication place?
Now If I can just find a mobile phone mast engineering place with some 2" hardline they don't want for that mag loop project!

Sunday, 15 November 2009

GQRP Valve Day II (November 15th)

Still hours to go yet but gone QRT...

Swear I heard Colin G3VTT at one point as I heard the familiar weep weep of his paraset but then lost him in the noise...

Anyway after over hour with no response generally as cq'ed for ages on every frequency now qrt but not a bad mix...

GM3VMB 15:29
OH1O 15:39
DL6KWN 15:42
DJ3KK 15:55
OZ5DX 15:57
DL8JJ 16:28

Freq's 3.51140 (3.7W), 3.50746 (4.2W), 3.52800 (5.6W) 3.57903 (7.3W). Missing 3.560 +/- few KHz means few qrp stations find me.

The DL 'HOT' contest meant there were a lot of qrp stations on the 80m band.

Glass RCA 6V6 valve (1940's vintage valve) TX (as per GQRP rally at Rishworth) with manual change over switch to RX with FT897 (with 20dB attenuation in line when 6V6 TX active).
Antenna 6-BTV vertical. (Not ideal 80m antenna for UK working!)

Videos of the Valve Tx in action tonight:
video

video video

Saturday, 14 November 2009

M1KTA QRP TCVR (HB-1A/KX1 clone... started that way anyway)

Been asked to post full circuits and details of the PIC code...

I cannot do that just yet as want to see 1. what KK7B and Kanga US might have to say about it first as the R2/T2 stuff is his, not spoken to him yet! and 2. if I can manage/afford to kit it and after any I get feedback from beta builders but not even at that stage yet!

If it doesn't become a kit/project (and I want the PIC code to be worked on by builders too) I will post details.

Thanks all for interest and messages though after George G3RJV RadCom Dec 2009 QRP column comment about the blog.

72

Dom
M1KTA

Thursday, 12 November 2009

MOBO SDR


As those that follow GQRP list/yahoo group might have noted a few weeks ago I asked if anyone else was building the MOBO SDR setup.

"
Apologies maybe a bit cryptic but definitely QRP......... please is any
other member building one the MOBO V4.3 Beta ? If so please can you
contact me off list.

For those who will ask questions what this is about read these...
http://sites.google.com/site/lofturj/mobo4_3
http://sites.google.com/site/lofturj/softrock6_3

...not for those who don't like SMT.
..."

Anyway Tony has just sent me all the Softrock parts required and Art, KY1K and Alex, 9V1AL have agreed to send me a set of PCB and components so I'll be building a MOBO beta V 4.3 shortly. The project will eventually be adding 24 bit 192KHz sound via USB not a sound card and the idea will be to also work with Simon HB9DRV and his new SDR software www.sdr-radio.com to create a frequency agile all band HF transceiver, using only a USB connection so plug and play that can be homebrewed in a modular manner.

HF TestSet


Browsing on the train whilst coming back from seeing the guys at Comic Relief I came across the HF test set from the 4 states QRP group. This isn't actally new but they are rekitting it
http://www.4sqrp.com/kits/hf_testset/hf_testset.htm
I dropped Wayne an email and had an exchange about it and one of his older projects (minibootsII that I lent to Michael MI5MTC at GQRP rally). I already checked and I have everything in the junk box/shack shelves so I am going to build an M1KTA version. Probably manhatten style as I realise it's nice to have some ugly in the shack too.

This will add a

Frequency Counter
Crystal Oscillator
Wideband Noise Generator
Audio Oscillator
50 Ohm Dummy Load
RF Probe
Time Domain Reflectometer
to the M1KTA homebrew bench.

For no particular reason except I enjoy it I build a fair amount and I find bits of test kit are infinitely valuable, I'll update this blog post as I build it.

All proceeds from kit sales are being used to finance OzarkCon QRP Convention so wander over to their site and order one.

The blog listed in RadCom December 2009!

Just advised of this so found the copy of RadCom December 2009 that I had not even opened yet, along with QST, PW and a few other electronic magazines. It seems G3RJV, Rev George Dobbs wrote about the blog advising readers to come a take a look which was a nice surprise.

One note though....The HCQRPC, Home counties QRP Club, http://hcqrpc.wordpress.com/ the founders are:

Hedgehog #1 Paul G0WAT and Hedgehog #2 Nicolas M1HOG

I'm Hedgehog #8 Dom M1KTA was lucky enough to be asked to give a talk at the first HOGCON, where I spoke about a trip to 3B8 I did in March 2008, the RadCom photo of me looking like I am demonstrating using a hammer to Hans G0UPL, was from that first meeting where Hans also talked, (if you hit a project like this it is bound to work) I think was the quote from HOGCON.

If you read the blog and want to ask a question or post a comment please do.

The blog contains a lot of different topics and may seem to bounce around, I used to try to update a project blog post directly rather than add new posts so it might not seem like much has changed sometimes.

Monday, 9 November 2009

M1KTA QRP TCVR HB-1A - KX1 Clone

Ok moved a bit further on this over w/e as my own HB-1A SMT build stumbled. I had added a solder bridge under IC6 (DDS) and IC5 (EEPROM). 101 SMT soldering means they should not have happened but I rushed the build and was late and made a simple mistake....

Anyway this post is to state that it looks like I have managed to add SSB to the AD9851 DDS and the RX chain. I have two alternate IF frequencies right now either 4.1952MHz or 11.0592MHz and could go either way. I also decided to drop the idea of making the SSB offset in the DDS and went with the 'standard' BFO setup where you use two crystal oscillators, set off set either side of the IF. Adds to the component count but then that isn't a bad thing.

The Softrock V9.0 Switchable BPF, along with the PIC-A-STAR and the QRP2004 designs have made me rethink the front ends and I am thinking that these should be switched. Now I don't mind winding toroids but I am thinking that some small SMT or through hole can type inductors might be workable for a 'no torroid' design.

Monday, 2 November 2009

A random cw log

I was looking through some old emails the other day and forgot I did this....

CW as a mode is winning me over and it is probably use that made the difference.

Why not also have a go at the RSGB CC on 80m too, just one evening a month, there are also ssb and psk evenings and it only lasts 90 minutes. Yes I know it is a 'horrid' contest but I find my biggest hurdle is still callsign recognition and responding practice from home during these contests helps. Many do slow right down for you. There really isn't much to remember or get wrong so you can focus on the callsigns you hear. I am sure the more of us that take part that are slow or rusty will encourage others to join in...

My best so far was using a full size vertical loop I put up on 80m for fun back in May and managed 34 at 12 wpm in an hour, it really was me too!
There were lots of GQRP members those ones in the log that night were:

QSO: 3551 CW 2008-05-22 1905 M1KTA 599 0002 M3WCK 599 002 #11717
QSO: 3551 CW 2008-05-22 1908 M1KTA 599 0003 G3JNB 599 004 #3432
QSO: 3551 CW 2008-05-22 1913 M1KTA 599 0005 MM0RKT 599 006 #11898
QSO: 3551 CW 2008-05-22 1914 M1KTA 599 0006 G4CZB 599 O9 #582
QSO: 3551 CW 2008-05-22 1917 M1KTA 599 0008 G0TPH 599 012 #7642
QSO: 3551 CW 2008-05-22 1922 M1KTA 599 0013 GW0ETF 599 026 #6822
QSO: 3551 CW 2008-05-22 1928 M1KTA 599 0017 G3YAJ 599 031 #2913
QSO: 3551 CW 2008-05-22 1934 M1KTA 599 0022 G3YMC 599 035 #11029
QSO: 3551 CW 2008-05-22 1935 M1KTA 599 0023 M0BZU 599 025 #10402
QSO: 3551 CW 2008-05-22 1937 M1KTA 599 0025 G4DDX 599 043 #141
QSO: 3551 CW 2008-05-22 1942 M1KTA 599 0028 G0WBC 599 026 #8999

I carried on afterwards and managed to put LA, EA, DL, F and IK stations into the log.

LM3914 and SWR and protection



I found a tin of bits and a page of scribbled notes and the above circuit.
Got a spare pair of LM3914 and LED as well so could display both fwd and rev not just the SWR.

Using the above as a guide I think I could do this also.... build new or salvage a CB SWR bridge (£3 from Rishworth) - as I need a voltage for FORWARD and one for REVERSE. I believe a stockton bridge would be frequency independent, I think the CB strip line one (stripline circuit) would work but might not work at VHF and might not be very sensitive but either will work. Using Shottky diodes instead of the originals might make it much more sensitive.

The circuit has the pins listed but basically you Connect the FORWARD voltage to the REF input on the LM3914. Connect the REFLECTED voltage to the INPUT pin. The data sheets says the REF pin has something like 25K of resistance across it for the comparators, you need a similar resistor across the REFLECTED line so they are seeing the same load so may need to play with various resistors.

If I were qrpp then the maximum output from the SWR bridge may be considerably less than the maximum input to the LM3914 so I could use a dual opamp (a LM358 can work with a zero input too can't it?) and amplify both channels - that will give you better sensitivity. I have some LM324 in the tin too.

I have a note that says use a small pot to apply the tiniest bit of forward bias to the REF pin to keep prevent a random display of segments when there is no drive.

The protection is adjustable... you source the output of the LM3914 at the level you want the protection to start and use it to trigger a relay or whatever so that the RF goes to a dummy load rather than to a PA etc...