What's on your Workbench?

[VK3ALB]

Lou, are you quite sure that it is not a pulse latching relay?

Owen

Hi Owen,

It certainly doesn't behave like a pulse latching relay and during my initial testing inside the transverter I didn't see anything that would make me think there was something wrong with it. I'm interested to hear why you think it might be a pulse latching relay.

[VK2OMD]

Lou, are you quite sure that it is not a pulse latching relay?

Owen

Hi Owen,

It certainly doesn't behave like a pulse latching relay and during my initial testing inside the transverter I didn't see anything that would make me think there was something wrong with it. I'm interested to hear why you think it might be a pulse latching relay.

Lou, they often have a lower resistance coil than an ordinary relay and may not be intended to carry that current continuously (the big idea of a latching relay). Clearly a latching relay works differently, and if you operated it like an ordinary relay... it won't work.

Have you searched for a datasheet, and checked the product code for options? Last I saw, Transco was purchased by DowKey, and some of their datasheets were available in an archive.

Owen

[VK3ALB]

Hi Owen,

I searched for the data sheet but no luck, just plenty of Asian wholesalers with many pcs available. Still, I learned a little bit about relays and certainly know how I'll be testing the next one I select for a project. Heat, prolonged power on and many switching cycles. No point being gentle with them, if they fail on the bench they will most certainly have failed in the field.

[VK4REX]

Hi Lou

Does your relay have 2 or 3 contacts on the side of the relay. Ones with 3 contacts are usually the latching relays, you pulse one lead or the other to change the relay over and there is a ground connection. Applying power to the latch coil for a long period will heat up the coil and possibly damage it. Current draw is around 1A when power is applied.

Rex

[VK3ALB]

Hi Rex,

They're pictured up the page a little, only two wires to the coil, current draw is 130mA@28V.

[VK2OMD]

Hi Rex,

They're pictured up the page a little, only two wires to the coil, current draw is 130mA@28V.

That is about the current specified for a Dowkey 402 series latching relay (looks similar to your pic). I would have expected more like 100mA for a normal relay.

BTW, latching relays don't have to have two coils, there is another option with only one coil and the direction of the current determines the direction of operation. Disadvantage of this type is that you need a H-Bridge driver.

Owen

[VK4REX]

Not quite on the work bench anymore, the first trial of mine and VK4OE's 47Ghz transverters.
Both have been built independently and not "air" tested before.
Contact was made this morning (7/11/2013) at 0022z at a distance of 91Kms on SSB.
Atmospheric conditions were not the best but good enough for the test to continue.

Rex

[VK3ALB]

A freshly reapired FT817. Most of you probably know that the ACC socket on the back of the FT817 has supply available on pin 1. This supply is always there as long as you have a battery installed or supply connected even if the radio is off. The power is provided via a 0605 series 10 ohm resistor (R1235) on the underside of the board.

If your radio should suffer the same fate you might consider the following modification - http://vk4ghz.com/ft-817-12v-acc-mod/

Note, not all FT817's are the same. Those of you with very old FT817's will find the board layout is not the same as Adam's radio. Proceed with caution.

[VK6WAX]

Gathered together a few round "to-its" and produced this reverse protected DC distribution box. Circuits for this kind of thing abound on the interwebs, this one based on an article by Dale Hughes VK1DSH "A polarity protection circuit using a power FET", Amateur Radio Jan/Feb 2011.

All a tight fit as evidenced by the offset LED. The FET used is STP80PF55 and the rather fine box is a Hammond 1550Q (Minikits).

[VK2EM]

If anyone should want a relay for 300W 2.2GHz (probably 2.4GHz) they should check here

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... SS:AU:1120

Bob is very reliable, and tests all his equipment before sale. I have bought many items from him.

[VK2ZRH]

Latest addition to the workbench - a desktop magnifier with LED lamp On the bench is a new Hohner Blues Harp (in key of C)

Christmas presents

Somehow, I think learning to use the magnifier will be easier than re-learning the blues harp - my old teacher, O'Shane (aka Shane) Duckham is SK.

Having cleared some scientific papers on Es from the bench, I have space to check out my new toys.

[ZL3RC]

I see you where one 6 meters when the picture was taken, top right.

HNY

Roger.

[VK2GOM]

On the bench is a new Hohner Blues Harp (in key of C)

Another ham with a Hohner Blues Harp I have had mine a number of years - again tuned to C. Not the bluesiest key... E would probably be better to keep (backing) guitarists happy.

The best trick I have discovered with mine, is to suck (not blow, entirely contrary to popular belief) the next to lowest note (ie. D) and then by employing some mouth cavity shaping, you can achieve some very bluesy note bends up to almost a full tone.

Great magnifier too Roger. It looked almost reminiscent of a toilet seat and lid at a glance Great for any SMT work. I wouldn't be without my magnifier when it comes to some of these tiny SMD's.

73 - Rob VK2GOM / GW0MOH

[VK4GHZ]

Currently upgrading both dual-band microwave transverter systems.

1) Removing the 3.4 GHz 8W PA module, and about to fit it's bigger brother!
This isn't a straightforward drop-in, because it involves removing the ThunderBolt (with it's display and associated switches) into it's own box first.
ThunderBolt has just been evicted!



This 3.4 GHz PA Upgrade is being documented on vk4ghz.com.


2) Installing a 10 GHz 10 W PA module.



See more of the DL2AM 10 watt PA module.

This should keep me off the streets for a while.

[VK4GHZ]

The ThunderBolt was evicted into it's own enclosure, and is now a self-contained unit.



See more pictures of the ThunderBolt rebuild on vk4ghz.com.

[VK5TM]

Not exactly on the bench anymore as I finished it, but I have built a simple VFO based on the cheap Chinese DDS modules and an 8-pin PIC.

You can see the details here if you are interested:

http://www.vk5tm.com/homebrew/dds_vfo_8/dds_8.php

[VK3YE]

A new 7 MHz monoband magnetic loop. Designed for apartments, units and retirement villages. 1m diameter. 100w power handling capacity. Uses 1.8m RG213 coax instead of vacuum variable capacitor. Parts commonly stocked by Bunnings. 1 - 2 s-points below full-sized antenna.

[VK2OMD]

First step in developing a new Guanella 1:1 tuner balun design, HiPot testing of the wire (the little red piece attached to the ground terminal).

General purpose current baluns for use with an ATU must withstand high differential voltages.

Withstands 7kV one wire, 14kV wire to wire, it will be fine.

Follow the progress of the project at http://owenduffy.net/blog/ .

Owen

[VK4EA]

Just completed a VK3ES cavity backed dipole, to suit my 1200mm dish with a f/D of 0.39.

Pretty fiddly, the 9cm version was way more difficult, onto the 2.4GHz version now.

[VK1JA]

The ThunderBolt was evicted into it's own enclosure, and is now a self-contained unit.

See more pictures of the ThunderBolt rebuild on vk4ghz.com.

G'day Adam,

I'd be very interested to know where I can buy two of those cases from - they're the perfect size for the projects I have !