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:

MHz	dB
10	0.6
50	0.8
145	1.4

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

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.

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.

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
• SWR LED
• 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...

Small Wonder Labs SW-30+ - shipped!

According to the "shipping status" page, it started its journey on 23rd April, 2008.

Keeping my fingers crossed...

A (great?) weightsaver for SOTA excursions

I am test driving an SGH-i780 smartphone that weights about 120 grams. It has:

• mobile phone
• internet surfing abilities
  
• embedded GPS
• photocamera 2Mpx
  
• videocamera 320x240
  

The operating system allows running all sorts of applications, including HAM related ones.

In 120g you have at least two devices you would probably carry along: the photocamera (say 150g for ultracompact year 2008 models) and the GPS receiver (that's 100g for my Geko201). You might or might not want to film your activation, that accounts for 400g or more. A light mobile phone is around 90g. Some crazy SOTAers have carried laptops with them, that is at least 1kg... Let's try a comparative table:

Tool	Weight (g)	Weight gain (g)	Cost (EURO)	Saving (EURO)
Mobile phone	90	Assuming i780	30	Assuming i780
GPS	90	with second	130	Costs 400 EURO
Camera	150	battery is 160g.	100
Videocamera	400		160
TOTAL w/o laptop	730	570	420	20
Laptop	1000		300
TOTAL	1730	1570	720	320

As of mid April 2008, this smartphone seems to be both a weight and a cost saver for technologically sick SOTA activators.

Drawbacks found so far:

• it has a non-standard connector for audio in/out, so it cannot be easily used for digital modes with PocketDigi
• the battery does not last very long, and Samsung sells the device with a second battery
  

Let's see how it performs next Sunday if WX allows for an excursion.

VCR Power Supply

While the shack is still a "work in progress", I disassembled a working (electrically) Philips VR301 3-head VCR. It still was a 98% through-hole device, and it shows A LOT of molded inductors.


The power supply caught my attention. It is in a shielded box, relatively compact and has many unmarked output wires. It might work as a bench lab supply, so I checked unloaded voltages.

On one line it has:

• +5.35V
• +13.7V
• -22V
  

On the second line:

• +5.25V
• +10.7V
• +24V
  

I had hoped for a dual +/-5V or +/-9V, but I got instead a nice +24V for driving a varicap diode.

I wonder how much current each line can source. That's for the next experiment. One day...

The shack is building up

New home, new shack!
Here's how it looked like on April 7th, when the laminated flooring was almost complete.