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 on: Today at 08:46:53 AM 
Started by W6GX - Last post by VE3VEE

Interestingly, his send speed was 18WPM on 160. Everyone slows down on top band!

Ray, hmm, is it possible you worked him on 30m, only wishfully thinking it was 160?  Grin Grin Grin


Marvin VE3VEE

 on: Today at 08:44:46 AM 
Started by K8AXW - Last post by KA4DPO
Do you have a gas range in the kitchen?  If you do, you have what you need close at hand.

As for the buzzer idea, it is the repetitious opening and closing of the coil via contacts that create the miniarc at the contacts.  Lenz's Law (for NN4RH's benefit - hi Ron) or simply the voltage produced by a rapidly changing magnetic field is - L di/dt.  When time approaches zero, well, the voltage approaches ...... the sky.

You can devise one very simply, if you have a junk box with an SPDT or DPDT 120VAC coil relay.  Simply connect a set of the normally closed contacts in series with the coil and you have, depending on the size of the relay, quite a spark gap machine.  Just don't connect an antenna to the contacts... :-)

You could do a similar thing with a small SPDT DC coil relay, but only half the fun, unless its a big one.

To take it a little further get an old automobile spark coil and connect the primary in series with the buzzer, other end to ground (negative terminal).  This will make a potent spark using a 9 volt battery and since you will only use it for a few seconds the battery will last quite a while.

Another way would be to get a large electrolytic capacitor and simply charge it up and discharge it through a carpenters pencil lead.  That will make one heck of a spark. and arc actually for a very brief period much like lightning.

 on: Today at 08:39:11 AM 
Started by AI4WX - Last post by W9IQ
If you are measuring the impedance values at the end of your 22 ft of RG-213, then you need to be aware that the coax is transforming the impedance that exists at the base of the antenna. Using the numbers you supplied, the impedance at the base of the antenna at 146 MHz could be 40-j13 or 57+j18 - either of which also indicate an SWR closer to 1.4 at the base of the antenna.

You may wish to bring the tilt of your radials up a bit to observe the effect on the impedance. Typically a 30 degree down tilt on the radials will get you closer to 50 ohms.

It is great that you are trying to learn more about antennas through experimentation. More hams should do what you are doing. But finally, be aware that an SWR of less than 1.5 is more than adequate to get your signal out. You will notice no practical difference in signal strength going from an SWR of 1.5:1 to an SWR of 1:1. In fact, in your case it will only yield about a 0.7% increase in signal strength or less than 1 dB gain on 2 meters. So the exercise of tuning the antenna may be instructive but the difference in performance is decimal dust.

- Glenn W9IQ

 on: Today at 08:37:27 AM 
Started by K6UJ - Last post by KD0PO

Marvin, I would expect that 5 element yagi to make its own propagation!

No, Mark, not up here. Up here in Canada we need 5 element monobanders just to match the G5RVs south of the US/Canada border.  Grin

Different CONDX up here, Mark.  Angry

Marvin VE3VEE

that made me chuckle!  Grin


 on: Today at 08:34:20 AM 
Started by W6GX - Last post by KD0PO
"listening" is how I got my 160 Q last night!

I was monitoring the 30M station. He announced that VP6J was QRV
on 1.813.5...
I tuned in and sure enough there he is S4 with a S2 noise floor calling
CQ CQ up.
It took several exchanges for him to get my call right, but I should be good to go.

I checked back several times over the next few hours and he was still there with very few callers. The best his signal got was S5 again with S2 noise floor.

Interestingly, his send speed was 18WPM on 160. Everyone slows down on top band!


 on: Today at 08:33:57 AM 
Started by K6UJ - Last post by VE3VEE

Marvin, I would expect that 5 element yagi to make its own propagation!

No, Mark, not up here. Up here in Canada we need 5 element monobanders just to match the G5RVs south of the US/Canada border.  Grin

Different CONDX up here, Mark.  Angry

Marvin VE3VEE

 on: Today at 08:30:42 AM 
Started by KC8KTN - Last post by W6EM
Thanks, but I'll give her the 'old wave.'

Energy density is the key, of course.  Things like ultra-thin electrodes and insulating layers.  Ever heard of graphene?  Electrodes one carbon atom thick are possible.

What KK is dropping is probably a new graphene electrode concept.  However, with thinness comes durability worries.  Drop it, dent it, and run like H***, because if you don't, who knows what internal shorts on super dense cells will do.  At least a big fire.

I can say, from experience, that LiPoly batteries have torched RC users' cars and garages.....and more.

If you want to do something productive, shoot off a letter to Dr. Ernest Moniz, DOE Secretary, and tell him he should be spending billions on large-scale battery research in order to realistically deploy renewable generators like wind turbines and solar farms to replace base load fossil fuel generation.

 on: Today at 08:30:41 AM 
Started by VE3YF - Last post by WB6MMV
I also would suggest using RG 142B or RG400 in place of RG58.  As pointed out earlier, using 11 turns on two -52 ferrites makes an excellent balun.  I measured mine using Steve's test measurement setup and got results that were quite similar.  I have made a large number of these for our local ham club and they work very well at legal limits.  They also solve lots of rfi problems.  And yes, I put them on Moseley beams despite what others say.  Its simply good engineering practice.  Most of the steppir's down here use a balun mounted on the boom.

RG400 is easier to find and wind then RG142B but both work well.  Short sections of RG400 can be found on the internet as that is the cable of choice for most all RF applications in aircraft so lots of spool ends are around.

Also, the -43 ferrite will work also.  My measurements led me to using the -52 on 20-6 meter beams.  I use -43 on 40 meter beams.


 on: Today at 08:22:22 AM 
Started by LOWLYTECH - Last post by N7EKU

First thing is to download the manual for your radio and at least read the first few pages.  On page 5 they have this really great section 5.2 called "Transmission" and they tell you how to test the transmission modes and make the adjustments needed for proper and safe operation of the radio. Cheesy  A good way to break a rig, or send out a poor sounding voice transmission is to start pushing buttons and operating without reading the manual.

For sure do the service modification for cleaning and then setting up whetting current on the relays.  They could be oxidized so you can't receive well now.  I had one of these rigs once and it was intermittant on receive until this was done.



 on: Today at 08:21:37 AM 
Started by W6GX - Last post by VE3VEE
Thanks, Ken. Not having a QSO in my log the first couple of days of their activity started to worry me Grin. GL with this ATNO.

Luke, you are absolutely right about the 14.040 mess. Sometimes it's better to listen a bit and move the antenna left and right to find out who it really is Grin. GL especially with the 160m QSO!

Marvin VE3VEE

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