Nov 112013
 

I have left a note with Carol at RSGB to confirm our exam status. Both Conrad and I have completed Assessor vetting forms and these will be sent off this Friday.

These may take two months to approve.

I am in contact with Steve Hartley from RSGB trainers sourcing the best training slides and information available which we can tailor to our needs.

Im sorry it is a long slog but we were left in the lurch a little.

We are hoping to get a batch of M6 and 2E processed in the new year.

I see no reason why we cant start getting to grips with some basic elements such as tuning a radio, re connecting and SWR tuning etc.

Other practicals such as morse awareness and making a qso can only be done whilst on a dedicated course.

Ill update you with progresss.

Robert
M0RCX

Nov 012013
 

Published on CCW reflector 31 October 2013

The design for the PA board is now finished. The Sentry SDR transceiver will use four Mitsubishi RD16HHF1 mosfets in push pull parallel.

I’ve just spent an afternoon measuring the transmit IMD performance of the prototype transceiver both as a transverter driver and transceiver.

The transmit third order IMD of the 1 mW transverter output at full power is -35 dB. At half power it is -48 dB. This checks that the USB sound card, transmit I/Q filter, upconverter and driver amplifier are working correctly and the output is very clean.

Testing the PA at 12V rather than 13.8V the transmit third order IMD at 25W peak output is -30 dB. Running at 13.8V will improve the IMD by a few dB but I wanted to test the worst case scenario.

What do these figures compare to? In recent QST reviews of amateur transceivers an Elecraft K3 had a third order IMD of -27 dB and the Flex Radio Flex-1500 came in at -22 dB.

The tests I’ve run used HDSDR as the SDR software with Spectrum Lab generating the two tone signal of 700 and 1900 Hz using Virtual Audio Cable. Measurements were taken both with a HP spectrum analyzer and a SDR-4+ receiver.

I also tried some digital mode programs generating PSK signals with similar results.

I’ve also run the transceiver and prototype PA on permanent transmit at full power for three hours so it should stand a few RTTY contests!

I should get the PA and low pass filter PCB board designed over the weekend and then it’s just some firmware testing before I can finish the main board PCB design.

Regards,

Chris, G4HYG

Jun 052013
 

Like a car manufacturer keeping their new designs under wraps until release date, NWRC has seen a few changes this week of which I am not going to publish but let you see for yourself on your next visit to the club.

In essence the possibility of SDR may well be greatly achievable within our budget if we purchase a used system .

Flex have had a bit of hype but the reviews on the Flex 3000 are quite impressive. Unfortunately we missed out on one at a steal of a price but we are keeping our eyes peeled and they seem to be more available in the UK than Apache Labs .

Use this link to see the Flex in action.

Conrad seems to have sorted the resolution of the wall display now and it’s looking much better. We were using it today to keep an eye on spots as we did some cabling work at the HF station.

We are keen to get our members hands on training and involvement with the club. In the past it has always been a bit of a sit and have a chat club but we would like to change that and encourage members of all levels and experience to share in the club experience.

Some good team working today with a fast black express delivery of some plugs from LAMS and Conrad and Mick sorting out the second HF Amplifier. It’s a loan unit and an Ameritron A811. Its assigned to HF whilst the new 6/4 dual band amplifier is under construction and the Acom is in use on the 6m station.

It works and rather well I am lead to believe although I wasn’t there to see it as i was demoted to lawnmower man and had the job of stimming back the nettles to create a non stingy pathway to HF and VHF towers.

Some automation of antennas has also taken place but how and what will be revealed on your next visit.

This Thursday I would like the HF Radio on and new members take turn to call CQ and get a few contacts under their belt. We will be there to guide you on logging and operating and assisting with any questions you have.

See You next time at the club.

73
Robert
M0RCX

Jun 052013
 

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The EQSL has now been received at the shack for this contact.

The contact was barefoot at 100W and the tower was fully retracted (down).

I can see Electronic QSL being the way forward with QSLing in general. All our stations are configured to send these automatically when we log using HRD.

If you also check our QRZ page you will find that a live feed is entered on to the page of our most recent contacts. We therefore encourage members to use the logging software wherever possible.

73

Robert

Jun 052013
 

 

0001 UTC 17th AUGUST TO 2400 UTC 18th AUGUST 2013 (48 hours or part thereof)

CALL CHANGED THIS YEAR TO GB4FCL ALL OTHER INFO IS THE SAME

This is a Special Event Station operated by North Wakefield Radio Club

Camping will be at World Farm which offers the highest focal point to Flamborough Head Light and close to the local bird sanctiry (Puffins).

This Annual event is normally a whole lot of fun and the pinnacle of the G4NOK calendar

Please watch for further postings detailing information on camping charges and directions.

 

gb4fl

 


gb4fcl

Apr 262013
 

Firstly I would like to publicly thank the two Micks, Robert, Karen and Tony who have been down to the shack and had a tidying up frenzy after the work we have been doing of late. The cables on the tower have now got plenty of cable ties and have been routed to the appropriate radios in the trunking. They have also got rid of quick a lot of ‘junk’ – in fact the shack looks enormous as a result and has a distinct echo :)

I have forgotten one or two things that have also been done – Robert will put me right. One thing is for sure we are making rapid progress!

Thanks for your hard work everyone.

I took a rather posh Rohde & Schwarz  ZVL Vector Network Analyser up to the shack tonight to have a look at the new 50/70 MHz dual bander. The tuning is not quite right, more on that later. Anyway here are the plot, still perfectly usable but we can make it better.

Click for full size images:

Screen grab of the return loss (RL) on 49-53 MHz. Maximum RL (min VSWR) is 50.398MHz - little high

Screen grab of the return loss (RL or S11) on 49 – 53 MHz. Maximum RL (min VSWR) is 50.398 MHz – little high

RL (S11) for 70 MHz. Minimum is out of band and needs to be improved.

RL (S11) for 69-71 MHz. VSWR Minimum is out of band and needs to be improved.

You may be wondering what this Return Loss or S11 is. I will do a little article explaining it, how it relates to VSWR and even links to a tool so that you can convert one to the other. To put things into perspective with the return loss shown on 50.398 MHz if you were to put 100W into the antenna a little less than 5mw would be reflected. This is a VSWR minimum of 1.01:1, pretty good! We just need to move it a little lower to the DX portion of the band, although the RL at 50.000 MHz dead is still 23dB which means 100W forward 0.5W reflected – actually quite good enough.

On 4m however 11 dB RL at 70 MHz means 100W forward just under 8W back, that needs some improvement I think.

I am fairly sure that the HF antenna is too close to the dual bander so we are hoping to get a longer stub mast.

Justin G0KSC has also suggested how I can improve the way that the choke balun is mounted – only a 5 minute job fortunately.

Mick and I were talking about the luffing winch and head unit bearing loading tonight, if we were to extend the stub mast appreciably and use a steel scaffold pole. He is a bit of dark horse that one, he knows a lot of stuff about a lot of things. It seems that our Mick has done some fairly serious mechanical engineering at some point.  So we’ll work stuff out properly and do the best we can. We all have a feel for these things but its always better to do the calculations and find a use for those redundant fag packets. Or we could do a spread sheet but then that would be like being at work for me!

The HF antenna is working marvellously though!

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