Quantcast
Channel: G4FRE RADIO BLOG
Viewing all 252 articles
Browse latest View live
↧

Austin QRP Club VIA Finally Built

March 21, 2017, 12:27 pm
$
0
0
I had seen the specifications for this Austin QRP Club Vector Impedance Analyser kit when it was first announced. It covered 1 to 150MHz or 8kHz to 1.17MHz (good for LF) and offered a range of different format results display on it's TFT Display; no need for a computer to drive this one!  I bought the kit from K5BCQ's web page about a year ago and recently decided it was time to build it. The microprocessor board is prebuilt, the TFT display is prebuilt, the only board which needed building is the RF board which also connects the other two boards together. The RF board took about 2 hours to build

The recommended enclosure was obtained; not cheap at around 20 pounds, but makes for a neat unit. I used an SMA connector for the antenna port.

Not surprisingly the software had been updated since I bought the kit, but it didnt take long to do the upgrade following the instructions provided.

Initially the unit was powered by six Eneloop AA cells mounted in the supplied battery holders connected via the regulator board supplied with the kit providing regulated 5V

The flash screen came up immediately and following the instructions in the manual a 2 MHz to 30 MHz open/short/load calibration was done. My Alpha-delta DXCC antenna was connected and the VSWR, Return Loss and even a smith chart plot were obtained

VSWR Plot

Return Loss

Smith Chart

It is possible to export the data to a computer and process it in any way you want. 
 Another useful display is the Alphanumeric display which shows the parameters as numbers. One use of this is to measure capacitors and inductors at RF Frequencies 
Alpha Display
Very impressed with the unit, especially as it cost under 100 pounds. Cannot wait until the transmission measurement add on becomes available

↧
Search

AQRP VIA Power Source Improvement

March 30, 2017, 11:31 am
$
0
0
Running the VIA from the rechargeable Eneloop cells from the VIA was tolerable for a while, but the batteries had to be extracted from the battery holders in the unit every time a recharge was needed.

The VIA documents mentions using a "2600mAH power bank". These provide a regulated 5V output from a USB connector and can be charged from a phone charger with microUSB plug.  Ebay had them for 99 pence (shipped) so a couple were bought.


Testing them to power the VIA externally proved they would work fine. The BIG issue was that  power bank box was too big to squeeze into the VIA so the power bank contents would have to be extracted from the package. This was done but it was quickly discovered the controller boards are destroyed if 5V from a charger is applied without the battery connected. The LIPO cell still worked. Time to look for a more robust charger for my growing LIPO cell collection

Adafruit had a Powerboost 500 charger/booster which looked to be well suited. It also had the advantage that the VIA could be powered at the same time as the cell was being charged. One was obtained for $15 and squeezed into VIA with the LIPO cell, as shown below.

Controller  shown top Left, just above the LIPO cylindrical cell
The system powers the VIA for well over an hour, which is very acceptable. A hole was made in the case to allow the charged and charging LEDs to be viewed with the case lid on.


↧
↧

Homebrew PiHPSDR

April 1, 2017, 10:26 pm
$
0
0
Having seen the Apache-labs version of the PIHPSDR I wanted to customise it to fill my needs, so I needed to assemble my own

All the needed information , with the software,  is at John Melton's github site https://github.com/g0orx/pihpsdr  The hardware shopping list includes. RaspberryPi 3, 7" Official Raspberry Pi LCD,  8 push buttons, 4 rotary encoders, case and power supply.

All the items were mounted in a 12x7x2" aluminium case obtained from Mouser, The display was held in place with plastic channel finishing strips from B&Q.

Front Panel View

Inner View
Initially I used a $30 rotary encoder that I got off ebay, but being designed for attaching to a motor it was a bit big to go in the box. I replaced it with an HP  HRPG-ASCA # 14F which cost $5 off ebay which fitted nicely into the box.

When first built, I used a 5V 3A regulator bolted to the Aluminium case. However this was dissipating around 8.3V at 2A and was too hot too touch. I tried a series of diodes, each with 0.6V drop on the regulator input, but that also got hot.  The regulator was replaced with a DC-DC switching converter from ebay which kept cool. The negative lead of the power supply, and the negative lead of the RPI were both grounded to the case to avoid negative lead voltage drop issues which caused RPI brownouts

I also included a USB soundcard in the box so i could listen to both audio channels when remote from the ANAN. The audio connections were extended to sockets mounted on the Aluminium box. Due to the close spacing of the USB ports on the RPI, and to allow plugging other items into them, the plastic case on the USB soundcard was removed.

The total cost of the homebrew PIHPSDR was around £120




↧

ADF4351 Signal generator revisited

May 27, 2017, 5:29 am
$
0
0


My previous attempt at building a 35MHz to 4.4GHz signal generator here had been thwarted by  a fake chinese chip recorded  here. From consumer feedback it appeared that much less trouble was being had with the black ADF4351 chinese board with the 2x5 pin header. I also noticed that BATC were using one in their Portdsown DATV Transmitter. So I bought one from "alicehappy858" on ebay

It took 15 days to arrive, and ten minutes to rewire the header. One very important point to note is that the header pin marked "3.3V" is a 3.3V OUTPUT from  from the 3.3V onboard regulator, NOT a 3.3V INPUT.  5-9V needs to be applied through the tiny barrel connector on the edge of the board of the black version.

Having taken care of that issue I again used my modified F1CJN software published here , modified to use the Adafruit RGBLCD shield that I had. The unit locked all the way from 35MHz to 4.4GHz and the Frequency counter agreed. Success at last!
↧

432MHz UKAC August 2017

August 13, 2017, 2:28 pm
$
0
0

Time for the annual 432MHz UKAC outing, mainly to try out some new equipment locally before taking it further afield. The new all digital KR400 rotator needed testing, as did the recently rediscovered DEMI ex TV transponder amplifier. Heavy rain delayed going to site, so only operated 2 hours. However 77 QSOS were made as G4NXO/p, best one being 390km into Paris. Equipment ran a K3S into DEMI Xverter, TV Transponder PA module running 100W into a 21 ele F9FT. The HA8ET mast head preamp was mounted at the base of the mast due to the length of feeder on the Yagi


↧
↧

5760MHz UK Microwave contest August 2017

August 28, 2017, 1:13 pm
$
0
0

Having previously finished encapsulating my 6cm amplifier, I was eager to try for some QSOs. The UK microwave groups 5/10GHz activity contest on July 27, G4DDK had given me a 5Ghz patch antenna which would be easier to use than my 0.6m dish. I ended up packing the 5760 EME transverter, the amplifier , and the KX3. As it was a 12V system everything could be run from the car battery

As the local site at the tump at IO82UA had a good takeoff to many directions North through southwest, it made an ideal starting point; if anything didnt work I would be close to home to get it fixed

The first attempt was with GW3TKH/p operating from the Blorenge IO81LS. Signals were easily exchanged, but holding the antenna in one hand, writing the log entries and tuning the rig was quite tiring!Signals were also exchanged with GW4HQX/p at the same location

.
The path SW to GW3TKH/P
 The next attempt was with M0HNA/p in IO91GI. He had linearity issues so no SSB, so we tried NBFM. No problems in exchanging signals, and the best DX at 94km. I next tried with G4ODA. Signals could be seen on spectran in both directions, but not loud enough for a QSO.

The Path  SE to M0HNA/p

I wanted to try with G3XDY and G4JNT, but both were too busy setting up skeds on ON4KST. Hanging around was not possible as I needed to move to the other side of the malverns to work G3ZME/p in IO82QL before the contest ended. I left the Tump and went searching for a suitable location. I found a couple of locations but it is amazing how big the field hedges are on the west of the Malverns which precluded their use. I ended up again going to Ankerdine Hill IO82TF, where despite pointing through dense foliage a qso with G3ZME/P was completed, again handholding the patch antenna.  By this time G4JNT was free, but the Malverns caused a major path obstruction.

A very interesting trip out and some interesting points learnt for future operations

↧

RSGB National Hamfest 2018

September 30, 2017, 12:08 pm
$
0
0
This years visit was made on Friday as usual. There was heavy rain as the outside area opened, so much so that the inside hall was opened early A used tonna 50MHz five element  yagi for £20 was purchased from the flea market with the intent of converting it to a lightweight 4m yagi. Indoors a four section 20' swaged mast was finally bought (I thought about getting one last year!) from moonraker

The usual big traders were in attendance, although some on a smaller scale than last year, for example Waters and Stanton. It was impossible to get near the QRPLABS stand as G0UPL had to queue of people placing orders. I have still to finally meet him after having previously had many transactions with him from Texas

The highlight of the trip was non transactional! A few months ago I assembled the BATC minituone receiver, but it failed to receive the DATV signal generated by the RPI, even though it passed self test so I put it aside. The BATC would be newark and I guessed would have real DATV signals, so I took the receiver along. Noel G8GTZ was only too pleased to try it out and it passed testing with flying colours. Now I can move onto assembling my Portsdown Transmitter modules
↧

1296MHz Trophy 2017

October 11, 2017, 2:01 pm
$
0
0



Having been to Dorstone two weeks previously for the UKAC with poor results to the North, I wondered whether it was conditions or if there was not just enough time to set up skeds on ON4KST. to work them.  Six hours of operation in the 1296MHz should provide an answer, especially as for the first time i could use the SCC M2I.

As there are no power classes in this contest the full 350W from the 4 x MRF286 amplifier could be deployed (as opposed to the 2 x mrf9060 in the UKAC) to the 44 ele Wimo. 48QSOS were made  with the best DX being DK2MN at 684km Some other noteable dx was PI4GN, PA0S, OT5A/P GD8EXI, GU6EFB and GI6ATZ. The only failure was with G4ALY who by the time i found him on CW my keying paddle springs had fallen apart. The only escapee on ON4KST was G8PNN, who admitted at the RSGB convention had been replying to M21 not M2I 



The conclusion of the operation was that with the extra time some of the weaker northern stations were workable, the site was alright

Things got so quiet towards the end i spent the last hour trying to receive the GB3ZZ DATV repeater. The 46km proved not possible (and having plotted the path on my return home I can see why!)

I also took along the 13cm system with the KX3 which although it could receive beacons produced no power, which turned out to be a DC switching issue



↧
Search

Making the K3 internal Transverter more External Transverter proof

December 11, 2017, 2:16 pm
$
0
0
Having suffered with the K144XV internal transverter's lack of useful output adjustment range, I finally decided to do something about it. The issue is that with the power control fully clockwise the 144 MHz output power is 9W. With the power control fully anticlockwise the output is 1W. This is the only band you cannot turn the output down to 0W!.  If you set the the IF level to -10dbm, fully anticlockwise is still 1W as is every other setting of the knob.

The issue was raised with elecraft over 3 years ago, but they said there was no software solution. They did point out that there is a drive pot in the module that could be adjusted to make the maximum level suit my transverter. After blowing up the pin diodes in my DB6NT transverters on more than one occasion, it was time to do it.

Reference to the circuit of the K144XV revealed the pot was labelled R87

After removing the K3 top cover and the Transverter top cover, R87 was located between L3 and L4. It is shown in the following picture:-


Next a small hole was drilled to allow a trimming tool to adjust VR4 with the lid on the transverter, as shown below:-

I set VR4 to give 1.2W with the drive level set in the menus to 0dBm. The adjustment range is similar, but now there is no risk of overdriving and destroying the transverter
↧
↧

BARTG 2018 RTTY Sprint

January 30, 2018, 7:18 am
$
0
0



This is a fun contest. It starts and finishes at a reasonable hour (noon) and as a sprint only serial numbers are exchanged; no reports. The hardest part was that neither the confirmed dates, rules or the experts list were available on the BARTG web site or any hint where they were located before the contest

Radio conditions were poor. 15m only opened for 30 minutes on Sunday morning. 20m didnt have the usual quantity of far eastern DX. 40m was subdued. 80m was good overnight into the USA, the only failure was AD5XD in Texas, despite many attempts. The highlight was being called by YC4BGN on 40m Saturday night giving me the 6th continental multiplier (OC).

The dual vfo FSK configuration using a pair of TinyFSK worked very well using the method by K0SM , Although N1MM v1.0.7013 was supposed to support TinyFSK natively, when tried it showed highly corrupted text in the transmit window meaning it could not be used effectively to see what was being sent! Hence I resorted to the K0SM setup configuration

There were no equipment issues. I used my newly made accesory cable to replace the elecraft made one that caused trouble the previous weekend on the RSGB Data AFS which worked fine switching the KAT500

Results:-
        Band     QSOs     Pts  DXC  Are  Con  
         3.5      90      90    4    0    0   
           7     224     224    9    0    1   
          14     256     256   39   19    5   
          21       7       7    0    0    0   
       Total     577     577   52   19    6   


  SOAB100W section Score : 245,802


↧

10MHz Distribution Amplifier

February 1, 2018, 6:47 am
$
0
0


I have had a need for a distribution amplifier for a while now. Searching around I found the design by G4JNT in Radcom, which filled my needs. I redrew the circuit for 4 outputs and had PCBs made. I now have the units in my M1DST 10MHz Thunderbolt monitoring project and in my LPRO101 10MHz Rubidium source. The project is written up at http://g4fre.com/10MHz_distribution.htm
↧

RSGB Data AFS 2018

January 23, 2018, 7:54 am
$
0
0
The original plan was to operate with G4BVY from GW0FRE. However he was detained elsewhere so I would have to do it single operator, I decided to use MW2I

As it is a dual band (80/40m) dual mode contest (RTTY/PSK63) I could not just use MMTTY. At his talk on data modes at the Malvern club G4BVY suggested using MMVARI, which I hade never used before. Using it on AFSK you could have one window for RTTY QSOs and one for PSK31 QSOs. With Rogers remote guidance (including a Skype call 10 minutes before the contest!) I managed to get it going

Originally I had intended to use the KPA500/KAT500 at 400/100W output. However during pre-contest testing there were many issues with the switching. Most often with the correct antenna and band selected on recieve, when i went to transmit the amp would change band (sometimes with "Invald" on the KPA500 display) the atu would switch antenna and try to tune it and the KPA500 would fault out.  With time running out a decision had to be made, so i used the K3s barefoot at 100w with its internal ATU and the 2 antenna ports switching between bands

Conditions were poor on 40m, just 6 RTTY (no PSK) qsos into central europe. 80m had a reasonable rate
              PSK        RTTY      Total
80m       52           90           142
40m       0             6              6


Grand Total 148 QSOs

After the contest I investigated the issue further. It was narrowed down to the 15pin to 15pin aux cables supplied by elecraft with the KAT500 and KPA500. One worked fine but the other appeared to have an intermittent short between the band1 pin and the ptt (hence why it changed band when going to transmit).  During the following week I cut apart the molding on the faulty cable and saw how unreliably it was assembled. Although their was a clamp that held the screen, which was doing a reasonable job on the screen, it did absolutely nothing to stop the cables in the bundle moving and rotating. This had happened and the band data lead was wandering around the plug, touching the PTT pin.



I looked at the cost of a replacement cable, but at nearly 50 pounds and the photos not assuring me the cable grip method was any better I decided to make my own

A search of the Farnell website revealed a 15 pin HD metal shroud that had a selection of cable clamps that would grip any cable firmly. They were not cheap (6.52) but I needed reliability.

As the Elecraft aux cable used only 10 cores I found some 10 core+screen cable and made a pair of 1 metre long 15 pin male to female cables; enough for the KAT500 and KPA500. I also made a shorter cable that could be used to connect the KAT500 to the KPA500 when the ATU is sitting on top of the PA,

 I also found my 3 metre 15pin to 15pin all pins connected cable (with moulded plugs), As it had 2 female connectors, i chopped it in half and with two of my newly purchased connectors made a pair of 1.5m male to female leads. These cables are useful when connecting to my K3 switching box which has a possible need for all pins
↧

432MHz AFS 2018

February 7, 2018, 2:04 pm
$
0
0

The final leg of the RSGB as usual is held in February starting at 0900. This would be the first opportunity to try the newly built G4DDK Iceni 432MHz Transverter, along with the K3S, solidstate amplifier, HA8ET masthead preamp and a 20 element yagi at 20'


As the first 2 hours overlapped a French Cumulative contest there was some interesting DX to be worked, which made up for the lack of ANY DL/ON/PA stations! There were a few snow flakes before and after the contest but during the contest freezing feet were the main hazard

The only equipment issue was the audio from the K3S. At times there would be buzz on the monitor audio on transmit. The monitor was set at level 2 and the buzz was equally as loud Eventually it was correlated with the fans running on the K3S.  The fan was running more often than previously as the Iceni was placed on top of the K3S, as shown above.

Searching the Elecraft website after the contest revealed there was a mod for this issue, although they were slightly confused as to whether the hum was on transmit or receive. The fix was a 470uF capacitor mounted on the KPAIO3. The mod was done and the issue resolved
↧
↧

HF NFD 2108

June 7, 2018, 1:45 pm
$
0
0
Unable to go out portable for this years contest i decided to have a go in the fixed station with the remote MW2I station

The interesting part of the fixed section is that if the station worked is not a portable or is not a multiplier then it is valueless. Hence no point in calling cq and working streams of no point qsos

The K3 was used at 70W with the Cushcraft A3S 2.5 element tribander on 10/15/20 and the 80m dipole on 40/80/160m

The remotehams software was used to remote the k3 front panel and send the audio to the client computer. Remote desktop was used to run the N1MM logging software on the server computer. Keying was achieved witha K1EL winkey at the server end

 It was only possible to operate 11.5 hours during the contest but the goal of 100000 points was achieved:-

 Band     QSOs     Pts  DXC  Pt/Q
   1.8      32           248    7   7.8
   3.5      63           220   17   3.5
     7       52           182   18   3.5
    14      60           200   27   3.3
    21      50           136   26   2.7
    28      20             52   13   2.6
 Total     277         1038 108   3.7
Score: 112,104

The 80m dipole worked surprisingly well on 160m and 40m


↧

CQWW RTTY 2017

September 25, 2017, 10:29 am
↧
Search

RIP Meg

June 11, 2018, 9:44 am
$
0
0
 Meg Robinson 1947-2018 (G7FRE), M0FRE, (KB2NCP) N2NQI, 9H3MW


W2SZ/1 50MHz 1993
↧

K3S HI SIG WARNING

August 5, 2018, 11:03 am
$
0
0
While testing before the IOTA contest at G8X the K3S came up with the error "HI SIG warning" From the manual:

"An extremely strong, sustained signal (e.g., a broadcast station’s carrier) may be causing
excessive post-mixer amplifier current when operating on the present band. The K3 will automatically turn the preamp OFF, and in extreme cases will also turn the attenuator ON"

After disconnecting the antennas and turning the rig back on again the same error was displayed, and all controls were sluggish. At this point the K3 was used as a replacement and survived the whole contest

An Internet search suggested that the IF amplifier following the mixer consisting of Q8 and Q9 had now got shorted devices. Elecraft support were contacted and quickly responded confirming this theory. The devices were discontinued but some were found on EBAY. These took 24 hours to arrive and when fitted resolved the issue. The IF amplifier in the sub receiver had escaped unscathed. As a note Q8 and Q9 were easy to replace as you just have to remove the front half cover underneath the K3S, thet are soldered to the underside of the motherboard

Elecraft support also mentioned that for a time the K3S was shipped  R66 in the IF amplifier as 10 ohm 

"On K3S, make sure R66 is 15 ohm  E500610 not 10ohm. We briefly shipped with it 10 and reverted back, **AND at the same time changed R60 & 75 so if R66 is 10 ohm, change it to 15 E500610 and R60 to 150 ohm E500251 and R75 6.2 ohm E500265"

My K3S was one of these radios so having replaced Q8 and Q9 and checked it worked I changed the values of R60, 66 and 75.

↧
↧

A weekend at Dorstone on 71MHz and 50MHz

October 25, 2018, 11:00 am
$
0
0
Having got my 71MHz NOV and built a 71/437 MHz Transverter,  I decided I needed an outing to exercise them.  I noted the 50MHz AFS was happening shortly so I decided to combine the two events in a weekend in Dorstone IO82LB. G8GTZ would be out at IO91GI (136km) over the weekend so I would have someone to work

I set out from Malvern on Saturday morning. Got to site and erected the new 2" mast system with the 5 ele 70MHz Powabeam.



I transmitted to G8GTZ who could see my signal a few db above the noise floor but could get no video.  However I did receive Noel's 15W signal and decode it easily at 125kB.

Noel retired to fault find his receiver while I retired to the Pandy arms for the night

The following morning I returned to the site and assembled the old 5 ele Tonna antenna along with the K3S and KPA500 for AFS.

 

After a very slow start I managed to work 96 stations, best DX being PA4VHF at 640km. During AFS Noel informed me he had fixed his receiver by disabling his laptop PSU to lower his noise floor 10dB, so we could try again.
When AFS finished at 1400 I took down the 6m 5 ele yagi and put up the 4m 5 ele yagi again. This time Noel received my signal:-

I also received Noel, this time with much better MER, up to 24dB which shows the system had some performance left for a longer path

I returned to Malvern Sunday evening after a great weekend, including my first DATV QSO on any band


↧

DATV Predriver Amplifiers

November 14, 2018, 1:39 pm
$
0
0
Having built the BATC Portsdown DATV transmitter I realised I needed amplifiers between it and my final amplifiers. The neatest solution would be to use Mitsubishi Power Modules. I managed to obtain some

I used RA070608 on 4m, RA081317 on 2m, RA07H4047 on 70cm. Each could produce around 7W. I managed to source some G4DDK PA/LPF PCB onto which these modules would fit.

Each amplifier was mounted in a diecast box, with an SMA input connector (to match the Portsdown output connector) and BNC output connector to match the following amplifier. A BTS4140 high side switch IC driving a 78L05 regulator was used to provide switched 5V to bias the module. Switching was achieved with an earth on transmit signal from Portsdown. The amplifier also provides an earth on transmit output to switch the following amplifier.

Each module produces 7W output with all harmonics over 55dB down on the fundamental

  

The Fourth amplifier, the one on the right, is a Chinese broadband 2 to 900 MHz 2.5W amplifier from Ebay, that may come in useful one day!
↧

DATV Expedition to Clee Hill

December 13, 2018, 2:31 pm
$
0
0
To coincide with the BATC activity weekend on 9th December I decided to go and see what could be worked from Clee Hill, IO82QJ. especially as G8GTZ said he was going to Win  Hill IO80XH which would allow an attempt on the 71MHz RBTV UK Record. I also packed a 2m system
4m System 5 lele @5m

Signals from Noel were succesfully received on 4m using the 71MHz/435MHz Nacton Transverter and Noel had little trouble seeing my transmission using the Portsdown to drive th Transverter, extending the UK distance record to 160km. I then took the 4m antenna down and put up the 2m antenna. I used the contest MHP with the HA8ET preamp that supplied some pre-selection for the minituner. Unfortunately the Portsdown Transmitter couldnt produce any 2m output, so I switched to the Adalm Pluto. This enabled me to generate a signal so Noel could see and give me my 1st 2m DATV QSO
2m System 9 ele Tonna @ 5m

The G8GTZ 2m signal from 160km




↧
Viewing all 252 articles
Browse latest View live
Search