Repairing a Bird “Termaline” dummy load and watt meter

 

disassembled-bird-termaline

My prized Bird watt meter stopped giving reasonable readings last year.  A check revealed that the resistance had changed from 50 ohms to approximately 65 ohms.  Opening up the dummy load I found that the cooling oil reservoir was empty.  I emailed Bird to ask for a quote on a replacement resistor element but received no reply.  I then canvassed my ham friends and was lucky to find that Dov, 4X1KP had an exact replacement resistor.

The photo below shows the new resistor next to the burnt original.

replacement-50-ohm-resistor-element

I polished the inside surface of the metal funnel that contacts the far end of the resistor element and cleaned all contacts with contact spray, then inserted the new element.  An ohmmeter check showed just a fraction over 50 ohms.

checking-for-leaks

I then purchased a liter of paraffin oil (mineral oil) at the pharmacy.  Refilling was carried out on a disposable aluminum roasting pan (to contain any oil leaks).  I filled the reservoir with approximately 150 ml of oil and left the dummy load on the aluminum pan, to check for leaks (photo, below).   I then continued filling.

After more filling I noticed that the rear seal was leaking.  On disassembly and cleaning I discovered a tear in the rubber expansion diaphragm sealing the rear port of the oil reservoir.  The function of this diaphragm is to allow for oil expansion with heating.

expansion-diaphragm

I could not locate a diaphragm of this size in town so I made a temporary repair using a sheet of rubber from a mountain bike inner tube and an O ring of the right size.  The seal, so far, is holding.  This tear in the diaphragm is obviously the root source of the whole problem with oil loss resulting in heating of the resistor element.

 

If you have any concerns that the oil in your dummy load contains PCBs – write it off and take the dummy load, intact, to a chemical waste disposal site.

 

Paraffin oil from the pharmacy requires no special precautions – just don’t make a mess that will get the XYL on your case.

 

Moral

Before applying power to that dummy load you bought from the “junk” (electronics surplus), check the oil level.

Kenwood HF Radio TS 440 S

Kenwood TS 440 S is in mint condition. Has internal antenna tuner. Output is 100 watts. c/w microphone, DC power cord and manual.

asking $600.00 plus shipping if required.

Amateur Tower Protocols

A good one for the web. Its for Calgary but the laws are federal.
Rick

VE6RAK

This message for our members in Calgary, Forwarded from Wally:

Hello all,

I was asked to help find some info on what exactly the rules for towers were within the City of Calgary. I finally tracked down the brochure from the City regarding towers and it is attached.

Bottom line is they do not have direct authority over towers but encourage some protocols be observed (kind of a good neighbour policy). There is a City phone number to call if needed as well.

Basically, towers that do not exceed 15m, and with associated antennas that do not exceed 18.75m, do not require any consultation but Amateurs are encouraged to follow the notification guidelines in the document.

There may be restrictive caveats in some neighbourhoods though, and those should be listed in the property documents.

This would be a great document to have available to all hams via their respective club websites. If anyone sees that there are other clubs that are not represented in this email please forward a copy to them or send me their contact info and I can pass it along.

Thanks,

Dave VE6GAD

73 de VE6LK/AI7LK

..Vince

city-of-calgary-protocols-concerning-amateur-towers-1

 

After the rain

SAM_3171

Mushroom at VA6TJ

 

mushrooms

 

At VE6EGN

 

20160717_204154

At VE6HPY

 

To have your Fungal Photo posted email it to VE6BLD

 

 


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Letter or email of Thanks to Radio World Central

I won a couple of prizes at the 2016 CAARC picnic that were donated by Radio World. I will be in touch and thank them, but I see they have a page on their web site full of appreciation from various organizations. I think it would be appropriate for someone from the executive or the organizing committee to write an email of thanks. Come to think of it, I bet it has happened already.

John,  VA6SJA

2016 Raffle Winners

First prize, $500- Brad Kolody VA6BMK from Rocky Mtn House

Second prize, $200- Brian Davies VA6BD from Innisfail

 

Thank you everyone who purchased tickets to support the repeater system. See you next year!

Ham Radio – when all else fails

rural internet

Another QRP CW Kit

Super Rock Mite 40m CW QRP XCVR

schematic finished board

 

I bought this kit for US$16 including postage.  It features a keyer and substantial output power (see below).  I am posting some of the documentation inconsistencies that I found – hopefully this will smooth the build for others.  I bought my kit here   http://www.banggood.com/DIY-51-Super-Rock-Mite-RM-Kit-CW-Transceiver-Shortwave-Telegraph-p-991246.html

caveat emptor

 

Clarification to Bill of Materials (list of components)

  • C22 to C34 0.1 uF (104) disc capacitors. Approximately half of these capacitors tested within 20% of designated value, the rest within 50% of designated value. One capacitor was 0.028 uF.  All these capacitors were replaced with quality ceramic components testing within 10% or better of designated value.
  • C25 and C26: these are apparently the same capacitor. Documentation inconsistency between versions?
  • C13 to C21: 0.01 uF (103) disc capacitors. Less than half were within 20% so I replaced them all with good ceramic capacitors.
  • C35: 470 pF is necessary to prevent oscillation in the NE5532. Put it in.
  • Install the 100 pF capacitor located on the edge of the board between W2 and U3.
  • Y1, Y2, Y3: I used DIP header pins on the board and soldered the crystals to DIP sockets. Cut strips of 3 pins each and remove the center pin for the header on the board.  This arrangement will permit you to QSY to 7.030 / 7.040 when you find some appropriate crystals.  I found 7.0375 crystals in the same holder at US$0.10 each from Tayda Electronics and they should arrive in the mail any day now.  The pins will also let you painlessly try the VFO/DDS mod as per the March 2016 QST article pp 39-44.

board with caps and resistors

  • R2, R3: The schematic states that 1 W resistors should be used however 1/4W resistors are supplied. R3 is in series with the emitter lead of the 8050 driver transistor. I looked up the specs on this transistor and it can handle sufficient current to fry a ¼ W resistor. I didn’t have a 1 W 22 ohm resistor in my parts so I used a 2W resistor.  It protrudes a bit but fits. DO NOT use a wire wound resistor for R3 .  I check inductance of the resistor before using it.  For R2 I found a 1/2W 22 ohm resistor to substitute but I am not convinced it is necessary.
  • Electrolytic capacitors: The BoM shows 16V electrolytics.  My kit supplied 25V capacitors.  I strongly recommend that you do not use 16V units with a 12V (13.6V) supply.
  • D3: I have used the 1N4001 as a varicap however I also once wasted several hours troubleshooting because a 1N4001 diode somehow prevented crystal oscillation. I found that a BB221 varicap works well so that is what I used.
  • L1 and L2: My toroid calculator gives a value of 1 uH for 16 turns on a T37-2 form. The photo in the Engrish instructions shows 17 turns.  The LPF is not working well for me as I am seeing a drop of about 12 V P-P between the input and output sides of the filter section.  I used tested capacitors, within 2% of given value,  in the filter.  If anyone knows how to calculate the optimum values for L1, L2 please send me an email (QRZ.com). 

 

output filter with measurements

  • Q2 output transistor. I cut a mica power transistor insulator to fit under the heat sink and superglued it in place. The solder resist under the heat sink is a good insulator but …

 

final transistor insulator

 

  • LEDs: the long lead goes into the square pad. I used the green LED for receive and the red LED for transmit.
  • For the initial smoke test, after connecting a dummy load to the antenna terminals, I put a 10 ohm 5W resistor in series with the supply.  Current draw through the 10 ohm resistor was 85 mA.
  • I am getting 1.1 watts out into a calibrated watt meter using a 12 V battery as a supply. As mentioned above, there is definitely a problem with my LPF.  Once I get the LPF issue sorted out and up the supply voltage from my 13.6V buss, I expect to see several watts RMS out.
  • I used a USB to RS232 cable to connect the Rock Mite to my computer after finding the English version of the software. The software definitely does something but needs further research.  Who designs a board with an RS232 interface in 2016?  I was lucky my patch cable worked.

 

On the air:  I received reports of clean keying from several hams within 100Km.  A CQ in the evening brought a prompt response from Europe.  The QSK works fine.  My straight key was recognized after sending a few V’s.   The side tone leaves room for improvement.  I connected the audio out through a small digital audio amplifier module. I am confident that a good CW operator could fill his logbook using this transceiver.  For the rest of us I suggest working stations within a few hundred Km during daylight hours – the large number of stations heard concurrently after dark overwhelm my ability to sort out signals by tone.

The PCB layout shows some thought and some nice features.  It was designed without mounting holes made to slide into a ready-made case.  As may be seen on the photos I had a groove machined into some aluminum bar stock to hold the PCB.

This kit fails its “ISO9002 audit” because of the “instructions” and the poor quality of the disc capacitors supplied.  Google does a terrible job translating Mandarin to English.

 

 

 

New volunteer net control operator

We have a new volunteer for the Monday evening net controller.
Thanks to Maria VA6TFL for your willingness to help with the net.
Any other volunteers would be welcomed to add to the list.
Thanks to the five other net controllers for taking your turn.
Please check Updated Net Controller List under the Net info TAB
73
Bob VE6BLD
CAARC Net Controller Co-ordinator

 

  • Calendar

    December 2017

    Sun Mon Tue Wed Thu Fri Sat
    1
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    • Koffee Klatch Join the local Hams for coffee at the A and W in the Village Mall across from Wall Mart on the North hill in Red Deer. .Listen to VE6QE 147.150 MHZ plus 600 for directions. See you there!
    3
    • ARES Net on the CAARC repeater system
    4
    • CAARC 2 Meter NET Please check in to the CAARC net on VE6QE 147.150+ repeater.,VE6VHF 146.91-, VE6PZ 145.210 -, VE6UK 145.25 -...
    5
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    8
    9
    • Koffee Klatch Join the local Hams for coffee at the A and W in the Village Mall across from Wall Mart on the North hill in Red Deer. .Listen to VE6QE 147.150 MHZ plus 600 for directions. See you there!
    10
    • ARES Net on the CAARC repeater system
    11
    • CAARC 2 Meter NET Please check in to the CAARC net on VE6QE 147.150+ repeater.,VE6VHF 146.91-, VE6PZ 145.210 -, VE6UK 145.25 -...
    12
    13
    14
    15
    16
    • Koffee Klatch Join the local Hams for coffee at the A and W in the Village Mall across from Wall Mart on the North hill in Red Deer. .Listen to VE6QE 147.150 MHZ plus 600 for directions. See you there!
    17
    • ARES Net on the CAARC repeater system
    18
    • CAARC 2 Meter NET Please check in to the CAARC net on VE6QE 147.150+ repeater.,VE6VHF 146.91-, VE6PZ 145.210 -, VE6UK 145.25 -...
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    • Koffee Klatch Join the local Hams for coffee at the A and W in the Village Mall across from Wall Mart on the North hill in Red Deer. .Listen to VE6QE 147.150 MHZ plus 600 for directions. See you there!
    24
    • ARES Net on the CAARC repeater system
    25
    • CAARC 2 Meter NET Please check in to the CAARC net on VE6QE 147.150+ repeater.,VE6VHF 146.91-, VE6PZ 145.210 -, VE6UK 145.25 -...
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    29
    30
    • Koffee Klatch Join the local Hams for coffee at the A and W in the Village Mall across from Wall Mart on the North hill in Red Deer. .Listen to VE6QE 147.150 MHZ plus 600 for directions. See you there!
    31
    • ARES Net on the CAARC repeater system
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