Thursday, 25 February 2010


Recent questions on this on GQRP list about the docs for the setup of a TCVR using a set of boards from Kanga a few years ago... basicalkly starts off with the ONER TX from George Burt GM3OXX

> SPRAT has them all...
> SPRAT 45 Pages 4 & 5 ONER TX
> SPRAT 53 Pages 4 & 5 ONER VFO
> SPRAT 54 Pages 16 & 17 ONER 'IMP' RX
> SPRAT 56 Pages 3 ONER changeover and wiring for the whole setup on page 4.
I only know as I put the components together to build, in an OXO tin and printed them off (GQRP CD has the SPRAT as PDF).

I had to sub in a few things though.
IRF510 for VN10KM (N channel mosfet)
2N3906 and 2N3904 were used where NPN and PNP appeared.
I used J310 instead of 2N3819 in the VFO and RL1 from the ONER changeover was DPDT relay PCB mount version from Jabdog.

Wednesday, 24 February 2010

Testing Audio Transformers

(Circuit for meter details at bottom)
As I am probably daft playing with valves I had to figure out some things for AF transformers and such like.

This was written by Brian Clarke VK2GCE and appears (to me anyway) to be the clearest description of how to do it with minimal kit. My notes in bold after each section.

Testing audio transformers

© Brian A Clarke VK2GCE

1 Test equipment required

Multimeter – analog or digital

Audio signal generator – fixed frequency or variable (I have a cheap Maplin kit that does sine, saw, ramp and square waves from about 10Hz to about 25KHz, I added a little speaker so I can monitor the tone and a little frequency counter as well but they are not nesessary). If don't have one then look for a circuit for an AF generator, it really doesn't have to be complex and could be build ugly style.

Variable resistors, 1off 25k to 50k and 1off 10 Ohm to 500 Ohm (Carbon, I found wirewound will add errors to measurements)

Connecting leads

Audio voltmeter- preferably calibrated in dBm, sensitive down to –60dBm
(I use an analogue meter, dad gave me a while back no markings or who made it. Audio philes may hate me saying this but I just want rough tests and not HiFi testing so this is also true, audio is AC, as long as your meter doesn't have any unusual restrictions about frequency response (most DVM don't work well at AF), you should be good to go. Set up a 1khz tone (just a bit higher than a normal 700-800Hz cw side tione) and plug it into the AC inputs of the voltmeter and see what you get, if you get almost no response you can't use it, that simple). You could attempt to build an Audio voltmeter too, at bottom of post I include one possible circuit, or use an oscilloscope like this one but I was trying to limit the kit list!

2 Identify windings

Use the multimeter to identify continuity between the various connections.
For an output transformer, the high resistance winding, single ended or center-tapped is the primary
For a microphone, line or an inter-stage transformer, the higher resistance winding is usually the secondary
centre-tapped windings, the two halves may not be exactly the same resistance, especially on E+I cored transformers
There may also be a screen winding, which may or may not be connected to the frame.

3 Measure dc resistance

Use the multimeter to measure the dc resistance of each winding; write this down.

4 Measure impedance

4.1 Output transformers

  1. Connect the 100 Ohm variable resistor across the low resistance winding; initially, leave one wire open;

  2. Connect the 25k variable resistor in series with the high resistance winding and the output of the signal generator; set the resistance to 0 initially;

  3. Set the signal generator to 1kHz and near maximum output, which may be say, 20V rms

  4. Use the audio Voltmeter to measure the input and output Voltages; write these down

  5. Calculate the turns ratio = VIN/VOUT

  6. Connect the 100 Ohm resistor in circuit

  7. Reduce this resistor till the output Voltage falls 3dB (i.e. halves!)

  8. Increase the 25k resistor till the output Voltage falls another 3dB (i.e. halves!)

  9. Without disturbing the settings of the variable resistors, disconnect one lead from each

  10. Use the multimeter to measure the settings of these two resistors – these are the impedances of the primary and secondary – you may need to replace the 100 Ohm

    variable resistor with a lower value to get an accurate measure (I replaced with a sliding pot and fixed value resistors getting a rough value)

  11. Compare the turns ratio with the impedance ratio – do they agree? Allow for the dc resistance of the windings

4.2 Microphone, line and inter-stage transformers

Follow the procedure for output transformers, except:

  1. Connect the 25k Ohm variable resistor across the high resistance winding; initially, leave one wire open;

  2. Connect the 100 Ohm variable resistor in series with the low resistance winding and the output of the signal generator; set the resistance to 0 initially;

  3. Set the signal generator to 1kHz and low output, which may be say, 20mV rms (I used a Maplin AF sig gen)

Warning: do not exceed 20mV rms for microphone transformers

  1. As above

  2. As above

  3. Connect the 25k Ohm resistor in circuit – it may have to be a higher resistance;

  4. As above

  5. Increase the 100 Ohm resistor till the output Voltage falls another 3dB (i.e Halves)

  6. As above

  7. As above

  8. As above

5 Measure frequency response

Note: this section can only be done with a variable frequency signal generator.

  1. Reconnect the variable resistors without changing their settings

  2. Connect the audio Voltmeter across the secondary (I used the meter I mentioned, some DVM will not work!)

  3. Reduce the frequency till the output falls another 3db compared with steps 8 above; this is the lower 3dB point (My audio sig gen is brilliant for this you just press a button and the signal drops and you watch the meter)

  4. Increase the frequency till the output falls another 3db compared with steps 8 above; this is the upper 3dB point (My audio sig gen is brilliant for this you just press a button and the signal rises and you watch the meter)

  5. Write this information down – perhaps attach it to the transformer. (Wrote on mine with CD pen)

6 Measure power response (I never did this bit)

If you want to measure power response of output and inter-stag

e transformers, you will need a very good quality power amplifier, high power non-inductive load resistors and a CRO.

  1. In place of step 1in section 4.1 above, use a variable high power load resistor to achieve the value found in step 10

  2. In place of step 2 in section 4.1 above, use a high power variable resistor to achieve the value found in step 10

  3. Connect the audio Voltmeter across the primary;

  4. Set the input power to about 1W

  5. Connect the CRO across the secondary. Set the signal generator to 1kHz

  6. Increase the power input until the image on the CRT just starts to flatten – this is probably 3dB over the rated power of the transformer

  7. Reduce the power input

  8. Change the input frequency to the lower 3dB point identified in step 3 of section 5 above

  9. repeat step 6 at this lower frequency – the low frequency 3dB point may be at a much higher frequency than the lower 3dB point at low power [section 5] – it depends on how powerful the accountant was with respect to the design engineer in choosing how much core of what quality to use.

Precision Audio Millivoltmeter
Measures 10mV to 50Volt RMS in eight ranges


R1_____909K    1/2Watt 1% Metal Oxide Resistor
R2______90K9 1/2Watt 1% Metal Oxide Resistor
R3_______9K09 1/2Watt 1% Metal Oxide Resistor
R4_______1K01 1/2Watt 1% Metal Oxide Resistor
R5_____100K 1/4W Resistor
R6_______2M2 1/4W Resistor
R7______82K 1/4W Resistor
R8______12K 1/4W Resistor
R9_______1K2 1/4W Resistor
R10______3K3 1/4W Resistor
R11____200R 1/2W Trimmer Cermet

C1_____330nF 63V Polyester Capacitor
C2,C3__100΅F 25V Electrolytic Capacitor
C4_____220΅F 25V Electrolytic Capacitor
C5______33pF 63V Polystyrene Capacitor
C6_______2΅2 63V Electrolytic Capacitor

D1-D4___1N4148 75V 150mA Diodes

IC1_____CA3140 Op-amp
IC2_____CA3130 Op-amp

SW1_____2 poles 5 ways rotary switch
SW2_____SPDT switch

J1______RCA audio input socket
J2,J3___4mm. output sockets

B1______9V PP3 Battery

Clip for PP3 Battery


Connect J2 and J3 to an DVM-meter set to maximum amp range

Switching SW2 the four input ranges can be multiplied by 5

Total fsd ranges are: 10mV, 50mV, 100mV, 500mV, 1V, 5V, 10V, 50V

Set R11 to read 1V in the 1V range, with a sinewave input of 1V @ 1KHz

Compare the reading with that of another known precision Millivoltmeter or with an oscilloscope

The oscilloscope reading must be a sinewave of 2.828V peak to peak amplitude

Frequency response is flat in the 20Hz-20KHz range

If you have difficulties in finding resistor values for R1, R2, R3 & R4, you can use the following trick:
R1 = 10M + 1M in parallel
R2 = 1M + 100K in parallel
R3 = 100K + 10K in parallel
R4 = 1K2 + 6K8 in parallel
All resistors 1% tolerance

Another option is here

This is all for AF.

For RF you might want to look at N5ESE RF inductance meter

Saturday, 20 February 2010

M1KTA shack almost finished reorganisation

No new builds for a bit as minor problem with shack roof and had to replace some of the felt. Only found problem when started to reorganise. I must have missed the problem when tree came down last year and side swiped the back of the shack. Anyway the roof is done and the internal reorganise is 50% done now so should be back melting solder shortly.

The Yaesu FT897D will be retired (not going to sell as useful rig for IOTA trips) and use one of the two QRP2004 rigs I built as the main station set. FT817ND will remain as /P bicycle rig.

Going to finish the M1KTA version of a phasing rig I had started to blog as well as a HB1A/KX1/Drew Diamond clone , I had the boards with me at GQRP Rishworth. Adding RIT to the SW20+ and building a kit and manhattan FtTuthill80 TCVR.

As I have a 500KHz NoV will be finishing off building a station too. 500KHz RX will be SDR with HB9DRV new SDR-Radio and I'll run a remote server so you can hear/see activity on 500KHz from JO02bd, TX will be DDS based driving a MOSFET. The shack line up of DDS is pretty excessive so going to prune a few but before do that going to do a side -by-side comparison. I recently added a K5BCQ DDS to the line up and going to see which is best for the 500KHz TX (with a 4020 or 4060 divide by 8).

The shack clear out I seem to have managed to sell most of it except the Norcal2030 partial kit (just the things you cannot buy from Digikey et al), PFR-3 and ATS-3 rigs. Will take a lot of the rest not on the blog to CDARC March 7th Rally as will run a GQRP stall with M5CHH this year. Need an ATX based PSU got plenty of units to convert and will have a completed example with me.

Scheduled to build a K1 for someone else as I am a UK Elecraft builder now.

Monday, 15 February 2010

Clearing M1KTA shack of some items

Clearing the M1KTA shack of built kits I am not using to make way for and raising a bit of cash for newer projects so have decided sell a few things, I will sell these at what they cost me, check the respective websites in the list for original details, or do a google search or look on or QRP-L.

Please contact me directly via email if interested. My email address in is valid.

I'll update this specific blog post with details and images and add to the list but possible items include:

1. Completed Norcal power meter. I purchased and assembled the kit in 2008, it even appears on the blog. The unit is in pristine condition and works perfectly. Never taken out of the shack. I am selling it because I'm not using it and have other power/SWR measurement options in the shack.

Here are some basic specs. See the Norcal website for more details.
Frequency range: 160 thru 10 meters
Power level: 0.1 to 9.9 Watts
Accuracy: +/- 10%
Insertion loss: 0.1 dB
Power: Internal 9V battery
Connectors: BNC

Both digital and analog power displays. PEP for sideband. Audio Morse
output also.

I checked the completed unit against a calibrated power meter (I had used a Bird Meter as the callibration standard) and there was no marked error across the frequency range.

I include an assembly and operating manual.

Promised elsewhere now.

2. KD1JV, Steve Weber, QBSA
This is the shack base accessory to the ATS-3 rig.
Description: Actual size, 3" long, 2.55" wide, 1.45" high.
• Digital Dial
• 0- 9.99 Watt power meter, Forward or Reverse power
• 2 Watt audio amp
• 6 to 11 volt variable voltage regulator
Designed primarily for use with the kd1jv ATS series rigs to enhance base station use of the rig, the QBSA can also be used with other QRP rigs. IF offset for producing direct reading digital dial is programmable and IF offset arithmetic operations are pin selectable.
The QBSA may also be useful on your work bench. The frequency counter is usable up to 45 MHz (100 Hz resolution), and the variable voltage regulator can deliver up to 1 amp of current if heat sinked.

This cost me $45 but never used, AVR not even mounted and still in the foam.


3. KD1JV, Steve Weber, ATS-3B
This is a set of built boards and the LPF filters. The variable capacitors need to be added to the LPF and finally aligned but complete otherwise.

The notes on it say:
  • 3.1" x 2.2" board fits into standard Altoids tin.

  • Main board + one filter board weighs 1 ounce

  • 80/40/30/20/17/20 meter operation using plug in filter modules (supplied)

  • AD9834 DDS VFO for rock solid frequency stability

  • Sensitive 0.2 uV superheterodyne receiver

  • Double tuned receiver input filter for excellent image and out of band signal rejection

  • Four crystal IF filter and 600 Hz audio filter provide excellent CW selectivity and opposite sideband rejection

  • Audio AGC and limiting eliminates need for volume control.

  • Simple four push button, multi-function switches operate the rig.

  • RIT/XIT split modes

  • Unique "Direct Frequency Entry" using the paddle allows moving directly to any frequency in the band.

  • Single digit seven segment LED display for frequency readout and visual feedback, in addition to Morse annunciations.

  • Built in 5 to 35 wpm Iambic keyer, selectable A or B mode operation

  • Three keyer memories, up to 124 character total.

  • Reverse paddle sense option

  • Alternative "Stealth" paddle option allow use of tuning switches as paddles - saves additional weight by not needing an external paddle or use in emergency when external paddle or cable breaks!

  • 2.5 watt power output with 9 volt supply, over 4 watts with 12 volt supply - on all bands. Typical PA efficiency is over 70%

  • Modest 35 ma receive current for long battery life.

  • Operates down to 5.5 volts and transmitter still puts out usable power - 800 mw!

Cost me $200
Steve has retired this now.


4.KD1JV, Steve Weber, ATS-3A kit unmade
Original cost $180

Check too

5. KD1JV, Steve Weber, PFR-3
I built this whilst attending FDIM 2008. Ken Evans reviewed it in the QQ shortly afterwards. sells an updated version right now. I paid $200 for mine.

6. MKARS80 SSB Rig and CW interface
G6ALU, bought mine at the Leicester rally and the CW interface later.
I have a spare set of enclosures so you could improve on mine.

Promised elsewhere now.

7. BITX20A
Built kit.

8. Tayloe SWR Indicator/Bridge built Kit

Promised elsewhere now.

9. Through hole Firefly 20m
Part built kit

10. SMT Firefly 20m
Unbuilt kit

11. Rockmites

12. Rockmite AF filter kits

13. Softrock V6.2 RX lite kits
Several bands

14. Norcal 2030 partial kit

15. KD1JV Switched Longwire Tuner from was $40

Promised elsewhere now.

16. Tenna Dipper
Two of these one is complete other still a kit of parts.
Cost me $29 each

17. QRP2004 complete set of components for a build.
£187 (cost price)

18. Norcal VE3DNL Marker Generator
Cost $10

Thursday, 11 February 2010

500kHZ NoV Application Success!

As they say if at first you don't succeed try again.... OfCom have just granted an SRP to M1KTA for 501-504kHz and will be active on the band asap.

For those interested my application supporting docs.

Wednesday, 10 February 2010

5MHz NoV

My new 5MHz NoV arrived today, I let the old one lapse.

So should be QRV on 5MHz again soon.

/P from Snettisham

For those that might have worked me and wondered about the location as different to the one in qrz yes it was me /P from Snettisham yesterday (9th Feb).

Testing another antenna on the beach as well as using the trusty W3EDP on 80m.

Am building a /P DX trip rotatable wire 2 el vertical beam for 15/17/20m using 12m fishing pole using an IP56 ABS box to hold the balun, feeder etc and a cross member made from a couple sections of 5m fishing poles. It was a bit windy yesterday and I lost my reference buddipole as it blew over and managed to snap the whips off (again!)

Managed a nice chat with EI4IT, who was /P also in Donegal about the Lough Erne Rally 11 April. As MI5MTC said:

News item for RSGB news on Sunday 14 February 2010

Rev. George Dobbs, G3RJV is the world’s best known QRP enthusiast. He will attend a major QRP display at the Lough Erne Amateur Radio Club Rally on Sunday 11 April. The Rally is again in SHARE on the shores of Lough Erne, where islands abound with remains of ancient Celtic Christianity, George’s other keen interest.

Graham Firth, G3MFI, who is another listed in the International QRP Hall of Fame, is bringing the entire G-QRP Club stall, with lots of interest for low-power radio amateurs, and those intrigued by building their own rigs. Graham will also tour the Erne’s historic Second World War flying boat sites in the Battle of the Atlantic . On a second QRP table, Dom Baines M1KTA will display home-built kits, receivers, transmitters and accessories, similar to his very popular exhibition at the recent GQRP Convention. This will be another excellent opportunity to examine, ask questions and get expert advice from a master kit-builder.

A third display will be set up by Brendan Minish EI6IZ, from the Mayo Radio Experimenters Network. His will feature top quality Elecraft QRP kits from the USA , with much good advice from Brendan for novice and experienced kit builders alike. Along side he will have Elecraft’s latest high power K3 kit to build your own rig to standards of quality that match the best on the amateur radio market.

So, for all radio amateurs and experimenters interested in today’s thriving and traditional heart of amateur radio, home construction and low power operation, the place to be on Sunday 11 April has to be the Lough Erne Rally in Fermanagh , Northern Ireland . Details are on the usual rally lists.

Enquiries to Michael Clarke, Mi5MTC, Chairman Lough Erne ARC

FtTuthill 80

Following on from
fttuthill80.html a kit just arrived.

Also a spare PIC for a homebrew build.

Monday, 8 February 2010

16 pin SMT

Recent email thread on gqrp about how do you use SMT IC with those tiny pins.

These are samples of the 16 pin daughter boards I bought from FAR CIRCUITS a while back. I bought a bag full of all the possibles from 8 pin up to 28 pin TSSOP (those pesky AD DDS chips!)

The middle one I found wide body SOIC could use it by snapping the board in half and remounting it. You have to be a little careful though. The really small one can be used with short wires to place soic into 16 pin DIL sockets.

Sunday, 7 February 2010

Stereo input for PSK on Asus eeePC

Just asked about this..

----- Original Message ----
> Sent: Sat, 6 February, 2010 21:34:59
> Subject: PSK31 on an Asus EEE?
> Good day Dominic,
> I caught a note from you a couple of years back about using an ASUS pc mic
> input for IQ input. Do you know if the newest EEEs also have a true stereo
> in? I work mostly 40m QRP CW, but I'm thinking about building a PSK31
> transceiver for 20m and I'm trying to find a light, portable PC with good
> battery life to use with it. Any suggestions would be appreciated!

There is a eee forum... do a google for it and ID the chip.

The two eeepc I have (401G) 100% have quad input channels but using only 1!

That said even most consumer specs say stereo inputs on most laptops these days.

Friday, 5 February 2010

USB to Rig Interface and CW keying II

The prebuilt FT4232H mini modules are small.

In the photo is £1 coin for size comparison.

Just adding a few jumpers and using a a small USB cable and the unit added 4 COM ports to laptop. Going to build up a PCB using daughter boards to add 4 TSSOP MAX3243 RS232 line drivers and 4N25 optocouplers. Farnell have also furnished the 6 and 8 pin sockets for FT897 and FT817 CAT and Data connections.

Paul Harden on Diodes


Some common preferred devices typical to QRP rigs and as
available from DigiKey, Mouser Electronics, etc.

***** SMALL SIGNAL DIODES ***** (Pd=50mW)
DIODE Bv Vr Ir Vf @ If Ir @ Vr Trr CdM Cd(pF) @ Vr=
TYPE (V) (V) (nA) (V) (mA) (mA) (V) (nS) (pF) .1v 1v 10v
1N914 GE 75 75 25 1.0 10 25 20 4000 4 2.3 1.8 1.3
1N914A GE 75 75 25 1.0 20 25 20 4000 4 2.3 1.8 1.3
1N914B GE 75 75 25 1.0 100 25 20 4000 4 2.3 1.8 1.3
1N4148 GE 75 75 25 1.0 10 25 20 4 4 2.3 1.8 1.3
1N4448 GE 100 75 25 1.0 100 25 20 4 4 2.3 1.8 1.3
1N4150 GE 50 50 50 .7 10 100 50 4 2.5pF Max.
1N4148 is low storage-time version of 1N914

***** RECTIFIER DIODES (Low Power) *****
DIODE Bv If Ifs Vr(rms) Ir Vf Trr* Cd at Vr=
TYPE (V) (A) (A) (V) (uA) (V) (uS) 0.1v 10v
1N4001 50 1.0A 30A 35v 30 0.8v 3.5 50pF 20pF
1N4002 100 1.0 30A 70 30 0.8v 3.5 50 20
1N4003 200 1.0 30 140 30 0.8v 3.5 50 20
1N4004 400 1.0 30 280 30 0.8v 3.5 50 20
1N5400 50 3.0A 200A 50v 500 1.2v 3.5 50 20
1N5401 100 3.0 200A 100 500 1.2v 3.5 50 20
1N5402 200 3.0 200 200 500 1.2v 3.5 50 20
1N5404 400 3.0 200 400 500 1.2v 3.5 50pF 20pF
Schottky Rectifiers (very low Vf)
1N5817 20 1.0A 25 14 1000 0.3v 190pF 90pF
1N5818 30 1.0 25 21 1000 0.3v 160 65
1N5819 40 1.0 25 28 1000 0.3v 115 50

Bv= Breakdown v. If=Avg. forward current Ifs=Max. surge current
Ir= Max. DC reverse current Vr(rms)=RMS reverse volt.
Vf= Avg. forward voltage drop Cd=junction capacitance @ given Vr
CdM=Maximum junction capacitance
Trr= Reverse recovery time at If=10mA to 1mA
Trr*=Reverse recovery time at Ir/If=1 (for rectifying AC)

1. GE Semiconductor Data Book
2. Motorola Rectifier Device Data Book (DL151/D) 1992
3. Motorola TVS/Zener Device Data Book (DL150) 1992

IRF510 Data


Manufactured by Harris Semiconductors
Available at most Radio Shacks (although incorrectly labeled "IFR510")
Cost: $1.99 at Radio Shack (Cat. No. 276-2072)

The IRF510, IRF511, IRF512 and IRF513 are n-channel enhancement-mode
silicon-gate power field-effect transistors. These power MOSFET's are
designed for applications such as switching regulators, motor drivers,
relay drivers, and drivers for high-power bipolar switching transistors
requiring high speed and low gate-drive power. These types can be
driven directly from integrated circuits.

Vds Drain-source voltage 100v 80v 100v
Vdgr Drain-gate voltage 100v 80v 100v Rgs=20K
Vgs Gate-source voltage +/-20v +/-20v +/-20v
Id Continuous drain current 5.6A 5.6A 4.9A

ELECTRICAL CHARACTERISTICS (All types unless otherwise stated)
Igss Gate-source leakage 500nA (forward) -500nA (reverse)
Idss Drain current, Vg=0v 250uA
Id-on On state drain current 5.6A IFR510, IFR511
4.9A IFR512, IFR513
Rds-on Drain-source "on" Res. 0.4-0.54 ohms (device ON resistance)
Cis Input capacitance 135pF (at Vds=12v, Cis=180pF)
Cos Output capacitance 80pF (at Vds=12v, Cos=130pF)
Td-on Turn-on delay time 8-11nS ) These parameters define
Tr Rise time 25-36nS ) how fast the MOSFET turns
Td-off Turn-off delay time 15-21nS ) on and off when gate is
Tf Fall time 12-21nS ) driven with a square wave

Vsd Diode forward voltage 2.5v (dropped across the source-drain
due to the internal diode)


Output drain current (Id) vs. gate-source voltage (Vgs) at Vd=+12v
Vgs=4v Id= 0A
Vgs=5v Id= 1A
Vgs=6v Id= 2.8A
Vgs=7v Id= 4.8A
Vgs=8v Id= 6.8A

NOTE: Therefore, for a 5W QRP power amplifier, the gate-source voltage
should not exceed 5-6v; otherwise excessive current will attempt
to flow. A continuous applied Vgs >7.5v will cause Id to
exceed the maximum drain current rating of 5.6A (IRF510). This
will cause "catastrophic substrate failure" (commonly known
as smoke!).

What is the maximum frequency? Max. frequency is not specified, but
since Tr= 36nS (rise time) and Tf = 21nS (fall time), a total device
delay of 57nS occurs, worse case. f=1/t = 1/57nS = 17.5 MHz. Total
"typical" device delay is 25+12ns= 37nS for f= 27 MHz. This does not
take into account L/C loading of the output filter, etc., which will
lower the maximum frequency which the MOSFET will toggle on and off.


| O |
| | <--- Metal Flange (Drain) ISOLATE FROM GROUND!!!
| IRF |
| 510 | <--- Plastic TO-220 case
| |
I I I <--- Leads (Max. temp = 300C for 10 seconds, max)


GL de Paul NA5N (1-97)

Thursday, 4 February 2010

USB to Rig Interface and CW keying

Going to build an interface that will do CAT control and CW keying using USB

I can see I could start off with an FT232, FT2232 or FT4232 I cannot find samples in SSOP28, LQFP48 and 64 pin packages (You can also buy them <£8 from Farnell, Digikey or Mouser) and have single, dual or quad com port emulation, the FT232, 2232, 4232 datasheets cover the TTL-RS232 level conversion and self powered (from USB port) capability. There are prebuilt modules complete with USB socket and header pins.

If paranoid could add opto isolation for the keyed RTS/CTR signals using single 4N25 channel or dual channel 4N32 (22p from Farnell).

There are options available to buy (I already have a early G4ZLP USB CAT and K1EL USB WinKey interface) but looking for something that could be home brewed as pretty sure plenty made themselves a COM or LPT port keyer using a NPN transistor at some point.

Wonder if any interest in this as a kit?

Tuesday, 2 February 2010

Local metal hardware

Asked where I get some hardware and this is the flier from my local metals supply place, who also do helium gas... for those all important LF/160m antenna balloons

Water slide decal paper?

Anyone using laser or inkjet printer water slide decal paper?
If so where did you get it, any good and any hints?

If like me you made Airfix models as a youngster you'll remember it well.

As you can see phiotos from the blog I have used a CD pen and a brother label printer until now for simple ID labels, but I want to try and print some front panels with dials. I experimented with one option and it is possible to use normal non-gloss photo paper, print it in reverse and just like PCB fabrication iron on (the ink bonds to the pcb) and then 'wet' the paper and carefully rub it off but results are a bit hit and miss and you obviously cannot use on either plastic or a painted surfaces.

Monday, 1 February 2010

Old books

There have been a few threads on various lists recently about trying to find old copies of some texts which is a little like the proverbial search for hens teeth.

As one that has spent ages and ages in libraries for literature searches for MSc and PhD I know a little how to use the system for old out of print texts.

Recently I was searching for a copy of Terman's Radio Engineering from
1947 ( and this was how I found it....

I knew it was published in the US.

A recent search has been for Doug DeMaw's

"W1FB's Design Notebook"

The book details are:
# Paperback: 195 pages
# Publisher: American Radio Relay League; 1st edition (June 1990)
# Language: English
# ISBN-10: 0872593207

Armed with this you can find it in the US library of Congress catalog:
Will give you:
LCCN Permalink:

Look at the permalink info and you will find:
LC Classification: TK9956 .D4517 1990
Dewey Class No.: 621.384/12 20
With these that should mean you might ask/find it in a local big town
library maybe your local library can order a copy for you to
read/study, as they will understand the Dewey bit?

As it has an ISBN and was publishing in US recently that means there
should be copies in US copyright and some non-copyright libraries. I
wrote something in 1990 with a US publisher and I know it is there

If it was a UK published book you can do a similar search in the British library.

If the book was published elsewhere maybe start here to figure out where to start looking:

OK a tad geeky but I spent months in libraries doing literature search for university research so you learn how the system works.

As this is for radio I think we all know QST is like RSGB RadCom in this sense at
least, much of the technical article content from the authors also
appears in the annual handbooks and other published books it would
probably be safe to assume that much of the W1FB's writings would have
been published in articles in QST, ARRL handbooks and other places
over the years. Just like ARRL does with other writers e.g. KK7B
articles on R2 and T2 appear in QST and several ARRL books.

If you're an ARRL member you can search for articles by DeMaw at There are 600+ and
some (50+) that can be downloaded as PDFs. The rest you could get off
QST CD Rom collections.

Maybe a nice man from ARRL might make a pdf of the ARRL back catalogue available for members as a download as it doesn't look like they are reprinting much of it.