<![CDATA[ARCHIVE: Australian Ham Radio Discussion Forum ( AHRDF ) - *** READ-ONLY *** - LF, HF, MF]]> https://www.ahrdf.net/forum/ Thu, 23 Apr 2026 09:28:29 +0000 MyBB <![CDATA[Audio Clipping on Sideband?]]> https://www.ahrdf.net/forum/showthread.php?tid=1386 Sat, 17 Feb 2024 09:16:19 +0000 VK4JRH]]> https://www.ahrdf.net/forum/showthread.php?tid=1386
I've just recently obtained a bluetooth headset and adaptor. The bluetooth adaptor connects to my Yaesu FTDX3000. I've found that normal mic gains are far too high, so I've had to wind the mic gain back to about 7 to allow for this. Problem is, how do I know when the audio is clipping? Obviously, I want to get full modulation without clipping. I am feeding into a dummy load and monitoring on a RTL-SDR.com device, but it's hard to see if there is clipping or not.

See attachment. There seems to be lot's of harmonics. I've wound back the mic gain and there is less harmonics, but how do I know if I'm modulating 100%?]]>
I've just recently obtained a bluetooth headset and adaptor. The bluetooth adaptor connects to my Yaesu FTDX3000. I've found that normal mic gains are far too high, so I've had to wind the mic gain back to about 7 to allow for this. Problem is, how do I know when the audio is clipping? Obviously, I want to get full modulation without clipping. I am feeding into a dummy load and monitoring on a RTL-SDR.com device, but it's hard to see if there is clipping or not.

See attachment. There seems to be lot's of harmonics. I've wound back the mic gain and there is less harmonics, but how do I know if I'm modulating 100%?]]> <![CDATA[New 10m repeater VK3RBA]]> https://www.ahrdf.net/forum/showthread.php?tid=1373 Fri, 05 Jan 2024 11:39:06 +0000 VK3BA]]> https://www.ahrdf.net/forum/showthread.php?tid=1373
FYI, a new 10 metre repeater has been installed at VK3RBA Mt Buninyong near Ballarat.

It's currently a parrot repeater (with a 55sec TOT) until the licence comes through, then it'll be re-configured as a full repeater.

Repeater TX: 29.670MHz

Repeater RX: 29.570MHz

CTCSS: 123.0Hz

Built by Tim VK3TIM and site sponsored by Amateur Radio Victoria.]]>
FYI, a new 10 metre repeater has been installed at VK3RBA Mt Buninyong near Ballarat.

It's currently a parrot repeater (with a 55sec TOT) until the licence comes through, then it'll be re-configured as a full repeater.

Repeater TX: 29.670MHz

Repeater RX: 29.570MHz

CTCSS: 123.0Hz

Built by Tim VK3TIM and site sponsored by Amateur Radio Victoria.]]> <![CDATA[EasyPal SSTV]]> https://www.ahrdf.net/forum/showthread.php?tid=1316 Wed, 05 Jul 2023 06:45:40 +0000 VK4DCM]]> https://www.ahrdf.net/forum/showthread.php?tid=1316 <![CDATA[HFvertical radials...what is the most practical length of staple/pin/peg ?]]> https://www.ahrdf.net/forum/showthread.php?tid=1162 Tue, 22 Feb 2022 09:20:31 +0000 VK3LU]]> https://www.ahrdf.net/forum/showthread.php?tid=1162 Any voices of experience?

Nev]]> Any voices of experience?

Nev]]> <![CDATA[A selection of my QSL cards]]> https://www.ahrdf.net/forum/showthread.php?tid=1065 Thu, 29 Jul 2021 05:38:47 +0000 VU2NAN]]> https://www.ahrdf.net/forum/showthread.php?tid=1065
https://www.youtube.com/watch?v=qpv_qT2q_48

Those were the days!

73,

Nandu.]]>
https://www.youtube.com/watch?v=qpv_qT2q_48

Those were the days!

73,

Nandu.]]> <![CDATA[Loop antenna]]> https://www.ahrdf.net/forum/showthread.php?tid=1058 Mon, 12 Jul 2021 11:04:02 +0000 VK2ZIW]]> https://www.ahrdf.net/forum/showthread.php?tid=1058 I'm amazed this topic has not been discussed before.

I was looking at the 1m dia two turns loop antenna of 1/2" heliax when I noticed, it resonated at around 15MHz.
The coil had self capacitance with the turns spaced about 50mm. 

I ask, why not bring the spacing closer to bring the resonance down into the 20m band?

This brings me to why I am writing.

The hardest problem with loop antennae is tuning.

High voltage variable capacitors are difficult and having to adjust a single ended capacitor while "hot"
is even more difficult. So here in this discussion I'd like to see innovation in this subject, tuning.

Tuning methods:

Variable capacitance
================ Really not that easy. But with the two turn loop, the "hot" ends are back down near a zero voltage point
and if the conductor spacing adjustment is all that's needed, not too hard.

Variable inductance 
=============== Hardly ever discussed. However, in the Halcyon days, the Variometer was the go,
a smaller coil was placed inside the main coil and it was rotated to either enhance the magnetic field or oppose it.

Perhaps, a section of the loop could be more flexible to aid in tuning? There's been discussion here and the use of braided
coax discouraged. Well, why not use what Spot Welders and RF welders have done for years, copper strip? 

Fixed capacitance
==============   Scrap heliax is readily available and it's breakdown voltage is huge. Also it's dielectric loss is very low,
primarily designed for 100MHz and up, I'm fairly confident 20KV  would not stress 1/2" heliax one bit. (comments here please)]]> I'm amazed this topic has not been discussed before.

I was looking at the 1m dia two turns loop antenna of 1/2" heliax when I noticed, it resonated at around 15MHz.
The coil had self capacitance with the turns spaced about 50mm. 

I ask, why not bring the spacing closer to bring the resonance down into the 20m band?

This brings me to why I am writing.

The hardest problem with loop antennae is tuning.

High voltage variable capacitors are difficult and having to adjust a single ended capacitor while "hot"
is even more difficult. So here in this discussion I'd like to see innovation in this subject, tuning.

Tuning methods:

Variable capacitance
================ Really not that easy. But with the two turn loop, the "hot" ends are back down near a zero voltage point
and if the conductor spacing adjustment is all that's needed, not too hard.

Variable inductance 
=============== Hardly ever discussed. However, in the Halcyon days, the Variometer was the go,
a smaller coil was placed inside the main coil and it was rotated to either enhance the magnetic field or oppose it.

Perhaps, a section of the loop could be more flexible to aid in tuning? There's been discussion here and the use of braided
coax discouraged. Well, why not use what Spot Welders and RF welders have done for years, copper strip? 

Fixed capacitance
==============   Scrap heliax is readily available and it's breakdown voltage is huge. Also it's dielectric loss is very low,
primarily designed for 100MHz and up, I'm fairly confident 20KV  would not stress 1/2" heliax one bit. (comments here please)]]> <![CDATA[December 14 solar eclipse measurements announcement]]> https://www.ahrdf.net/forum/showthread.php?tid=1004 Fri, 20 Nov 2020 00:25:40 +0000 VK2XAX]]> https://www.ahrdf.net/forum/showthread.php?tid=1004 Feel free to share this info elsewhere
Quote:HamSCI is looking for radio amateurs around the world to help collect propagation data during the December 14 eclipse. Data collection requires an HF radio connected to a computer. Twenty-four-hour practice runs will be on November 21 and December 5. The data recording will run from December 9 until December 16. Details of the HamSCI 2020 Eclipse Festival of Frequency Measurement are on the HamSCI website. Those interested may sign up online, or contact Kristina Collins, KD8OXT.


Copied links are :
Details : https://hamsci.org/december-2020-eclipse...easurement
Sign up : https://forms.gle/C9PFSTeLf7xvCQDYA
Contact Kristina Collins : kd8oxt@case.edu
]]> Feel free to share this info elsewhere
Quote:HamSCI is looking for radio amateurs around the world to help collect propagation data during the December 14 eclipse. Data collection requires an HF radio connected to a computer. Twenty-four-hour practice runs will be on November 21 and December 5. The data recording will run from December 9 until December 16. Details of the HamSCI 2020 Eclipse Festival of Frequency Measurement are on the HamSCI website. Those interested may sign up online, or contact Kristina Collins, KD8OXT.


Copied links are :
Details : https://hamsci.org/december-2020-eclipse...easurement
Sign up : https://forms.gle/C9PFSTeLf7xvCQDYA
Contact Kristina Collins : kd8oxt@case.edu
]]> <![CDATA[MFJ -1848 Hexbeam HF Antenna Unboxing & Review - Part 1]]> https://www.ahrdf.net/forum/showthread.php?tid=964 Tue, 16 Jun 2020 11:48:04 +0000 VK7HH]]> https://www.ahrdf.net/forum/showthread.php?tid=964
https://mfjenterprises.com/products/mfj-1848

]]>
https://mfjenterprises.com/products/mfj-1848

]]> <![CDATA[Is it time to re-think DXCC after 3Y0I dx-pedition aborted.]]> https://www.ahrdf.net/forum/showthread.php?tid=769 Wed, 27 Mar 2019 22:46:27 +0000 VK4WDM]]> https://www.ahrdf.net/forum/showthread.php?tid=769
Is it right that a hobby, which is really what ham radio is, encourages people to attempt to travel to remote and dangerous places like Bouvet so a person sitting in comfort at home can chalk up another "rare one?

I have 238 DXCC entities confirmed, but I would be horrified if my quest to get 3Y in the log meant that lives were lost during the attempt to provide the contact.

Could the money spent on these "Dx-expeditions" be better spent in promoting AR as a whole rather than just satisfying the cravings of a just one section of the AR community? 

Is it time to re-think the whole DXCC idea?

73

Wayne VK4WDM  (I have been to Antarctica by ship and know a little bit of what that part of the world can offer weather-wise).]]>
Is it right that a hobby, which is really what ham radio is, encourages people to attempt to travel to remote and dangerous places like Bouvet so a person sitting in comfort at home can chalk up another "rare one?

I have 238 DXCC entities confirmed, but I would be horrified if my quest to get 3Y in the log meant that lives were lost during the attempt to provide the contact.

Could the money spent on these "Dx-expeditions" be better spent in promoting AR as a whole rather than just satisfying the cravings of a just one section of the AR community? 

Is it time to re-think the whole DXCC idea?

73

Wayne VK4WDM  (I have been to Antarctica by ship and know a little bit of what that part of the world can offer weather-wise).]]> <![CDATA[HF Verticals - straight or coil wound wire?]]> https://www.ahrdf.net/forum/showthread.php?tid=766 Mon, 25 Mar 2019 07:00:23 +0000 VK6ZMB]]> https://www.ahrdf.net/forum/showthread.php?tid=766
I was hoping to use a nice telescoping 7m fibreglass rod I have spare as the main vertical support and this got me to thinking...

When building a vertical like this is there any reason why you cannot use a spiral wind on the wire?  It would seem that way I could put up a 80m 1/4 wave by wiring the 20m element onto the 7m pole... right?   Is there a reason this doesn't work?  It seems to be the approach used by most CB whip antennas...right?

Ideally, what I want is an easily erectable vertical usable on field days that I could use for 80/40/20 via a tuner.  This would mean a 9:1 UNUN and 1:1 RF choke at the bottom to stop RF cmoing back into the tuner, an earth stake and a bunch of ground counterpoise wires.    Hopefully have a 20m long wire in the air (albeit only 7m up) should allow the tuner to work on these bands at least...?
OK - before he jumps on me I just found his link and am reading it now...

http://www.vk4adc.com/web/hf-projects/45...-whip-calc

OK - so it looks like the major trade-off is bandwidth huh. I wonder though, would a tuner be much help in that case?

Second trade off is the number of turns - 100m of wire on a 7m long pole = about 3000 turns! Ouch, good luck home rolling that beast...]]>
I was hoping to use a nice telescoping 7m fibreglass rod I have spare as the main vertical support and this got me to thinking...

When building a vertical like this is there any reason why you cannot use a spiral wind on the wire?  It would seem that way I could put up a 80m 1/4 wave by wiring the 20m element onto the 7m pole... right?   Is there a reason this doesn't work?  It seems to be the approach used by most CB whip antennas...right?

Ideally, what I want is an easily erectable vertical usable on field days that I could use for 80/40/20 via a tuner.  This would mean a 9:1 UNUN and 1:1 RF choke at the bottom to stop RF cmoing back into the tuner, an earth stake and a bunch of ground counterpoise wires.    Hopefully have a 20m long wire in the air (albeit only 7m up) should allow the tuner to work on these bands at least...?
OK - before he jumps on me I just found his link and am reading it now...

http://www.vk4adc.com/web/hf-projects/45...-whip-calc

OK - so it looks like the major trade-off is bandwidth huh. I wonder though, would a tuner be much help in that case?

Second trade off is the number of turns - 100m of wire on a 7m long pole = about 3000 turns! Ouch, good luck home rolling that beast...]]> <![CDATA[Loss of ABC Shortwave put fishermen at risk]]> https://www.ahrdf.net/forum/showthread.php?tid=762 Wed, 20 Mar 2019 20:37:24 +0000 VK2WP]]> https://www.ahrdf.net/forum/showthread.php?tid=762
Of course when ABC Shortwave was closed we were assured there is excellent VHF FM coverage in remote regions along with on line service.

https://www.abc.net.au/news/rural/2019-0...n/10922104]]>
Of course when ABC Shortwave was closed we were assured there is excellent VHF FM coverage in remote regions along with on line service.

https://www.abc.net.au/news/rural/2019-0...n/10922104]]> <![CDATA[HF Antenna Choice for new block]]> https://www.ahrdf.net/forum/showthread.php?tid=761 Mon, 18 Mar 2019 11:10:34 +0000 VK6ZMB]]> https://www.ahrdf.net/forum/showthread.php?tid=761
Looking for some advice on HF antenna setup at my QTH.  Currently have an Icom 718 working directly into a 40/20 fan type dipole and whilst RX is excellent, not having a lot of success getting out.  I have invested in a basic ATU (LDG 100) and looking to revamp my antenna setup.  I would like to be able to work 80/40/20 as a minimum.

My shack is a 50SQM colourbond shed in one corner of the block.  The adjacent corner (about 10m away) has a very large tree I can use as an anchor point up to about 12m AGL.  The roof of the house is at about 10m AGL and the distance between the tree and the house is about 33m so there is room for a fairly large antenna but the 80m dipole I have is just a bit too long.  I suspect that part of the issue I am having on 40m is that the centre feed on the dipole is too low.

Hopefully the group will indulge me with some opinions about the following questions!

1) Given I have a fair bit of room to work with, should I stick with some sort of multiple band dipole arrangement?
2) Is a end-fed type antenna through an ATU ever going to be as effective in this situation as a dipole? 
3) Can an ATU on a resonant long dipole also tune for lower bands?  I've never used an ATU before so not sure what their capabilities are and whether this is a silly question!

The other option might be a vertical but I am limited in room to run radials.  Can the 50sqm colourbond roof of the shed be used as part of a counterpoise in this setup?

Cheers]]>
Looking for some advice on HF antenna setup at my QTH.  Currently have an Icom 718 working directly into a 40/20 fan type dipole and whilst RX is excellent, not having a lot of success getting out.  I have invested in a basic ATU (LDG 100) and looking to revamp my antenna setup.  I would like to be able to work 80/40/20 as a minimum.

My shack is a 50SQM colourbond shed in one corner of the block.  The adjacent corner (about 10m away) has a very large tree I can use as an anchor point up to about 12m AGL.  The roof of the house is at about 10m AGL and the distance between the tree and the house is about 33m so there is room for a fairly large antenna but the 80m dipole I have is just a bit too long.  I suspect that part of the issue I am having on 40m is that the centre feed on the dipole is too low.

Hopefully the group will indulge me with some opinions about the following questions!

1) Given I have a fair bit of room to work with, should I stick with some sort of multiple band dipole arrangement?
2) Is a end-fed type antenna through an ATU ever going to be as effective in this situation as a dipole? 
3) Can an ATU on a resonant long dipole also tune for lower bands?  I've never used an ATU before so not sure what their capabilities are and whether this is a silly question!

The other option might be a vertical but I am limited in room to run radials.  Can the 50sqm colourbond roof of the shed be used as part of a counterpoise in this setup?

Cheers]]> <![CDATA[HF Verticals... How close is too close?]]> https://www.ahrdf.net/forum/showthread.php?tid=755 Wed, 13 Mar 2019 02:29:28 +0000 VK3LU]]> https://www.ahrdf.net/forum/showthread.php?tid=755 I can't find any info on the internet so far. Maybe I'm using the wrong words!
I am looking at the feasability of installing a 43 ft vert. and the only location I can put it is 5 metres from the metal clad wall of the back of the house ( which is in the europe direction Undecided) and 6 metres from the metal panel boundary fence.
Has anyone had any experience in this regard?

73 Nev]]> I can't find any info on the internet so far. Maybe I'm using the wrong words!
I am looking at the feasability of installing a 43 ft vert. and the only location I can put it is 5 metres from the metal clad wall of the back of the house ( which is in the europe direction Undecided) and 6 metres from the metal panel boundary fence.
Has anyone had any experience in this regard?

73 Nev]]> <![CDATA[9:1 OR 4:1 ??]]> https://www.ahrdf.net/forum/showthread.php?tid=668 Mon, 22 Oct 2018 04:52:25 +0000 VK4CCV]]> https://www.ahrdf.net/forum/showthread.php?tid=668
I can only place a wire up that is 88' in length.
At the centre it will be 33' and the ends drop down to 20'.
The Antenna will be fed with 450 Open Wire which will be 33' to the ground where the Balun will sit.
The run back to the shack will be around 40' where I will use LMR195 to the Tuner.


I have purchased a 9:1 but now wondering wether it should have been a 4:1 ??


VK4CCV   Pete]]>
I can only place a wire up that is 88' in length.
At the centre it will be 33' and the ends drop down to 20'.
The Antenna will be fed with 450 Open Wire which will be 33' to the ground where the Balun will sit.
The run back to the shack will be around 40' where I will use LMR195 to the Tuner.


I have purchased a 9:1 but now wondering wether it should have been a 4:1 ??


VK4CCV   Pete]]> <![CDATA[ACMA Spectrum Outlook : 5MHz / 60 metres]]> https://www.ahrdf.net/forum/showthread.php?tid=643 Sat, 22 Sep 2018 21:26:06 +0000 VK4ADC]]> https://www.ahrdf.net/forum/showthread.php?tid=643 From text edition for SEP 23 2018 - VK NATIONAL NEWS BROADCAST ON VK1WIA : http://www.wia.org.au/members/broadcast/wianews/

Also in MP3 edition of news available at: http://www.wia-files.com/podcast/wianews-2018-09-23.mp3



"The ACMA released their five year spectrum outlook, and unfortunately, due to a high demand for spectrum, Australian amateurs will not have access to 60m in the near future. 

Overall, no spectrum was added, and more importantly, no spectrum was lost. 

This has been a great outcome for our bands with pressure from 5G and internet of things, so make sure you get out there and use it!"]]> From text edition for SEP 23 2018 - VK NATIONAL NEWS BROADCAST ON VK1WIA : http://www.wia.org.au/members/broadcast/wianews/

Also in MP3 edition of news available at: http://www.wia-files.com/podcast/wianews-2018-09-23.mp3



"The ACMA released their five year spectrum outlook, and unfortunately, due to a high demand for spectrum, Australian amateurs will not have access to 60m in the near future. 

Overall, no spectrum was added, and more importantly, no spectrum was lost. 

This has been a great outcome for our bands with pressure from 5G and internet of things, so make sure you get out there and use it!"]]>