Saturday, September 09, 2017

Fixing the Palstar AT-Auto

I have owned an AT-AUTO since they were first released and its given good service. One area that it let me down was 10M.

On 28Mhz the coil can sometimes go into self resonance so tuning isn't possible. I fixed this by temporarily shorting the last four turns of the coil with some thin coax brain. It was an easy fix as the braid just slides between the coils and no soldering is required.

The problem with this solution is that I then lost the ability to tune on 160M :(

Working on 10M is more important for me as there is no (or very little ) RTTY on Top band. But I really wanted both!

I recently bought an MFJ 962 tuner for field day operation which includes a neat little feature built into the coil to damp self oscillation. This is an elegant fix and kudos to MFJ for solving the problem!

That got me thinking, and I designed a little device for the Palstar.

My solution is basically a folded piece of .3mm copper sheet that attaches to the opposite side of the coil support and is lifted by the tuning wheel as it travels down the coil.

on 10M the resonance damper sits on the coil. I used a pair of mini cable ties both sides to keep it in position (If it slid too far back it would foul the stop which sits proud of the coil end)

I soldered a sort piece of braid to the copper sheet which runs to the earth bar, this ensures the copper is earthed. Fold the edge of the sheet up where the tuning wheel runs. It will then lift the plate from the coil as it reaches the lower end (160M) tuning  

 So far it worked fine and I get tuning down to 160M with no self resonance on 28 or 29 Mhz!

Its early days but if it seems to work reliably. I may tidy this up and do an engineering drawing. To be honest it's very simple, 

A picture paints a thousand words so here is the solution.

If you own an AT-AUTO why not give it a go. It's inexpensive, and the Palstar AT-AUTO is an awesome piece of kit.! 

Now I look at the coil I may buy a replacement?

Monday, June 05, 2017

A new addition to the Shack - the Yaesu FT-891

My original shack in a box portable set up used the FT-450D.

This is a smashing little radio except in my portable setup it includes an auto-tuner with limited capability and I integrated the Power Supply.

The whole thing along with a fairly large mounting bracket was a little large and quite heavy to carry.

I decided a diet was in order and when the FT-891 came along it seemed the perfect rig being of mobile form factor and 100 watts

I learned a lot from building and using my original shack in a box so the new system includes

  • Flip off front (rather than a fold down front)
  • Microphone holder
  • FSKit RTTY interface and sound card
  • Volt meter
  • FT-891 
  • LDG Auto tuner
I excluded the power supply

As you can see it all fit in a neat little box with power, CW USB cables and antenna sockets at the rear.

The RTTY interface includes a volt meter so I can keep an eye on the batter volts whilst portable.

I ditched the mains power supply. I figured I could carry this separately and leave it behind if I intend to work of a battery.

The FT-891 really is a smashing little transceiver, like the FT450 no filters required but the filtering and DSP in the the FT-891 seems much more flexible. It really wowed me. It a step change from the FT-450D and would recommend it to anyone looking to go portable or mobile.

It also has excellent stability so I bought a second one to replace my old 2m 28Mhz IF

I use an FT-891 to drive my Kuhne Electronics transverter. A simple switching box ensures the 5 watts power is fed through a 20db attenuator to achieve the necessary drive. The transverter is GPS locked and after 3 minutes warm up listening to GB3VHF the stability of the rig is shown to be excellent with virtually no drift.

I tried an outboard speaker but the internal speaker is so good I stopped using it!


Thursday, August 25, 2016

MB6ISR - The SW London Fusion Gateway

I recently purchased an FTM-100DE so I could have a play with Wires-x and fusion

It’s been interesting to set things up and experiment with this mode.

One thing that drew me towards it was that unlike D-Star there was no need to register, just enter your callsign and if you wish a name into the rig when you power up for the first time and away you go... (More on this later)

I soon established that there was absolutely no Fusion activity on 2M and a very distant repeater (GB7HF) on UHF.

I use a now out of Production Araki YA485D vertical antenna that has very good performance and I live in a reasonably flat location. Placing my UHF antenna above the roof ensures it has a good range. Its a 2 x five eighths vertical and I remember back in the 80's using it to access BG3PT which was a RTTY repeater in Cambridge (Much to the suprise of the locals)

At 11M above ground level I was able to access GB7HF at Welham Green about 40 Miles north and started to learn how C4FM and Wires-x works. Trouble is the path wasn’t 100%. I also discovered that on 2M the FTM-100 suffered atrocious intermod from a local paging system, even with a PAR pager notch and bandpass filter I had problems so decided not to use the FTM-100 on 2M

My next purchase was a second hand HRI-200 which is an internet Gateway. That’s where the need to register arrives as Yaesu needed my details before allowing me access to the Wires-x network through the device.

A day later I was duly granted the appropriate access and just had to set up the HRI-200. This wasn’t that straightforward given the internet connection at my QTH. I played with lots of settings around fixed IP addresses but these were a red herring.. Eventually I worked out I had to enable port forwarding against a range of addresses for the HRI-200 to connect.

So here’s the rub. In the UK you cannot lawfully re-broadcast internet traffic without obtaining a NOV (Notification of Variation) from Ofcom.

I started by running the FTM-100 into a dummy load and using a second FTM-100 to connect to the Wires-x network. Thats was actually quite useful as I slowly learned how the system worked by connecting to a node then searching and selecting the rooms where I could work people in or just monitor.

After a little more researching I realised I could apply for an Ofcom NOV which would allow me to re-transmit the Wires-x traffic.

Application for an NOV is through the RSGB ETCC for the region. Dave G7UZN is the rep for the SE Region, He pointed me towards the online application form and some things to observe (Power, antenna etc). I completed and submitted the online form quite easily although you have to be careful to get the location and height above sea level correct.

There were a few issues to consider

  1. I could run on 2M unattended but the FTM-100 would suffer intermod causing drop-outs and in addition it would tie up 2M which I use for local chat and SSB DXing
  2. I could run 70CM but it required attended operation (Why?) so I couldn’t use it out and about mobile

I decided to apply for a 70CM NOV as it was the lesser of two evils. I built a small swich box so I could leave the Gateway running 24/7 and switch the rf to a local load when unattended,

I left allocation of the specific frequency to Dave and waited for a response. I was surprised how quickly I received my NOV and by the second day I had the power on the FTM-100 reduced to one watt (another condition) and the gateway running on 434.5125Mhz

I’m home most days from 4pm so if you live around SW London and own a set capable of C4FM, hit the DX button on your transceiver and see if my gateway responds.

Here is a MB6IFR now installed in a corner of the shack -

The MB6ISR equipment is

  • Lenovo ThinkCentre M91p SFF Quad Core i5-2400 8GB RAM 250GB  SSD Windows 10 Professional 64Bit Desktop PC running Wires-X
  • Devolo powerline adaptor delivering 100MB/s ethernet (and no, it doesn't interfere with my HF!)
  • Yaesu HRI-200
  • Yaesu FTM-100DE
  • Hombrew switch unit and load 
  • Bird Truline with RF-port for frequency measurement
  • 8M LMR-400 feeder
  • Araki 458D Vertical
  • TTI Instruments frequency counter (10Mhz GPSDO locked)
I haven't set up a room for SW London as there are already lots to choose from and the gateway is open to all users who can select what they want to listen to. I must say I enjoy listening to America Link and UK Net Hub traffic.

I will see how things go and maybe set up a 2M Gateway in the future. 

VY 73 Rex G8UBJ

Sunday, August 18, 2013

MY 2M Station

I thought I would post my 2M station details.

I have owned the FT-225RD for a number of years. Its been quite modified but nothing that can't be reversed. These include

  • Mutek front end
  • Separate RX port 
  • External Amphenol relay for RX/TX switching
  • The microphone includes a home brew compressor to  improve performance slightly
  • Mods to quieten sideband noise of the VCO
  • External PTT sequencing to protect the relay contacts from the...
  • Tokyo Hy-power HL350Vdx which is a courtesy addition for those hard to reach DL and HB stations
The IC-202S is a recent nostalgic purchase. This was the first transceiver I owned back in the 70s and I remember the fun working GW for the first time HI HI. It had some "Issues" but their mainly sorted now. 

Tune up yielded 5 Watts once I adjusted the 2M band pass filter correctly (Bypassed on RX). The ALC works well throttling it back to 3 watts but I did notice some overshoot...

I plan to fit rechargeable batteries and take it portable. See you on 2m SSB? 

Friday, December 28, 2012

Round up 'em doggies

Happy 2013 to all, lets hope its a good one. 

I achieved a good end to 2012 by coming first place in the 2012 ARRL RTTY Roundup

Of course there weren't that many entrants for England but I was top. It looks like running up a good number of multipliers (running all bands and chasing continents/countries) paid off. Congratulations also to Mike K4GMH winning the single op category for NA, hes always a big signal and I often work him on all bands. The 2013 ARRL RTTY Roundup is next weekend so I will see if I can up my 2012 score and secure another win.

I built a reasonably good VHF station this year. FT-225RD + Mutek front end driving a Tokyo High Power VHF amp to 300 watts +

My 2M array seems to have gone faulty (I think it may be the splitter) so as soon as the high winds die down I'm going to make repairs. 

The 2 x 4 ele Cushcraft boomers work well but I think I will replace them with a single long yagi.  Probably another Boomer as they work so well.

I'm up to 159 countries confirmed on HF RTTY through LOTW so I hope the double century isn't too far off. Maybe 2013 will be the year?

Anyway, I may have a busy year at work but I'm sure I will see you all on HF RTTY over the weekends?

Wednesday, April 18, 2012

A word on fraud

It would appear someone is using my name and call G3VZL to advertise equipment and then defrauding purchasers. I'm not the first this has happened to or the last.

If you ever see an advertisement with my call only those with my email G8UBJ.IO91UJ(at) GMAIL.COM is a valid advertisement. BTW I very rarely advertise and if I do I invite viewing/testing at my QTH!

Unfortunately this sort of thing will happen and so long as people are stupid enough to -
1 Set up a website without sufficient security checking at registration

If you see an advertisement for Ham radio equipment check the seller is valid through another site like QRZ.COM and LOTW

Do not send money, please report this to the authorities.

VY 73 Rex G8UBJ

Saturday, January 21, 2012

The FT-1907R UHF Mobile

I  recently started looking for a UHF transceiver for the shack. I know its easy enough to buy something like the FT-8900 but I have separate antennas for each band & I really wanted something I could leave running. 

I thought Alinco were about the only company left selling single band UHF transceivers until I discovered the FT-1907R.
 As you can see its a companion to the FT-1900 2M transceiver from Yaesu.

I found a Greek company selling this on eBay which surprised me as its not listed on the Yaesu dot com site. Either way it was quite a reasonable price and delivery was quick.

Initial testing showed that it did provide 55 watts output as specified and on the air was reasonably sensitive. I'm sure that if this gets to the states we can rely on the ARRL to put it through its paces so I won't go further into testing as my facilities are limited.

Transmit and receive runs from 400 - 470 Mhz continuous.

At the heart of the The PA stage is Mitsubishi RF Mosfet module capable of 60 watts

I found that like the FT-1900 this gets quite warm during extended transmit so I will publish a fan modification in my next post.

 As its a UHF rig an N-type connector would have been a nice addition. This was quickly fixed.

The rig comes with the usual Yaesu accessories (Even the sticky Yaesu label). I found the user guide listed on the Yaesu Russian site but strangely its only mention is on a brochure where it says Asian market only

I'm not sure why its not more widely available; maybe its early days or maybe Yaesu are trying to protect sales of their multi band transceivers in Europe and North America?