28 May 2008

Six meters mobile does work ...

... when propagation helps!

That's the case of yesterday 27/5/2008 with a super ES opening when I could work HA3UU (JN96), 9A3GI (JN95), HA807PL (JN97), YT1VP (JN94) between 1630 and 1700UTC.

I could also hear SV and I7 stations. All those I could hear were working DL and G as well: there were several ES clouds.

This morning I greeted IW1FZV and IZ1ERV in a local QSO, since the band was closed.

The mobile shack - inside.

The mobile shack - outside

PS: all these mobile contacts were done in SSB with 5W.

26 May 2008

Operating QRP mobile on 6m

The 2008 sporadic-E Spring season has started, so did I with home>office and office>home 6m QRP mobile activities.

The first attempt was on Friday, May 23 between 1500 and 1545 UTC, on the way back home throughout the banlieue of Torino.

The setup consists of:
  • FT817, 5W, SSB
  • homebrew earphone-microphone adapter
  • modified CB antenna to 6m
On 6m a 1m long antenna has a minimal loss compared to a full 1/4lambda vertical. A urban environment does not help, though! The adapter includes up/down tuning buttons, as in the original 817 microphone, and a switch to use an external voice keyer for automatic CQ.

I checked the DX cluster before getting in the car, and there were no spots to/from my area, but the band was open indeed: always try a scan through the (beacon) band before giving up!

A few observations.
  • Even last year I had noticed that calling CQ when QRP mobile is not a successful way to achieve some contacts. Search&pounce has proven to be more effective with my setup when the band is open and stations are calling CQ.
  • VOX operation is cool, but noise in the car can turn into pain (open windows, horn, ...): better add a flip PTT switch, so your hands are free except when you have to change TX/RX. Moreover I suffer from some kind of VOX apnea...
  • Paper logging the contact is awfully dangerous especially in the city traffic if you are both the driver and the operator. I do prefer to record the audio with an MP3 player/recorder and then fill in the log, but this requires the audio to be broadcasted in the cabin, so VOX disabled.
This June/July 2008 look for me on 6m between 545z and 630z and after 1530z!

22 May 2008

Magmount base, cable attenuation

Once I've seen the lossy look of the RG58 coax cable, I did a quick loss measurement with the MFJ-259:


Given a cable length of 5 meters (I think), this is not the best performing RG58 ever.

21 May 2008

Magmount base, one more fix

New problem on the new magmount base: the PL-259 connector.

Moving the coax cable right at the plug sent SWR from 1:1 to infinite. This is a sign either of a short or a broken connection.

Heated the soldering iron and found out two things:
  1. it was a short caused by erroneous (criminal?) coax preparation
  2. the crimp-on section for the coax braid was loose and I could pull the coax out with no effort
I re-peeled the coax and replaced the PL-259. Now it works.

Morale: if you care about your finals, check the plug assembling quality on your new magmount base!

Now I wonder how bulky the pseudo RG58 coax is! Will do some measurements soon.

05 May 2008

The SW30+ is here!

23/04 to 02/05: 9 days including a weekend, a national holiday and a stop by the customs. That is how long it took the small packet to come.

I had to pay extra 13 EURO as import duties and postal service theftcosts.

The PCB is really compact. I could fit 4 SW RTXes into the one I had chosen, or all accessories: battery, antenna, key, log.

Building will begin shortly.

First mod will be a better polarity reversal protection, in place of the 1N4001 D13 diode. I will instead use a fuse and a surge-suppressor diode.

02 May 2008

Additions to my SW30+

This is a brainstorming reminder, so that I won't forget to add useful modules to my SW30+, when it arrives.
  • improved polarity reversal protection (bypass D13)
  • keyer, using SKC and an additional 78L05
  • integrated LED frequency counter (with on/off switch)
  • integrated LED SWR bridge
  • integrated antenna tuner (z-match or L-network?)
  • output power pot
  • vernier reduction tuning pot
  • trail-friendly box
So, on the front/top panel there will be:
  • tuning pot
  • RF gain control
  • keyer button
  • counter's LED and switch
  • power switch
And on the back panel:
  • antenna BNC connector
  • power plug
Location TBD:
  • key, probably on the LHS
  • headphones, probably on the RHS

I keep on dreaming...