Welcome to new 160m band blog

This blog is the replacement of the my preview Topband blog here http://topband.blog.cz/ because of an aggressive advertising and flash banners inserted by the blog provider. For older posts access You can visit the old blog link which will exist still... but it will not be updated anymore.

Effective from 1st Jan 2017 please paper QSL via OM-bureau only.

Tuesday, January 24, 2017

The half sloper antenna - everything depends to your installation...

Proper installation by Jens, OZ1LWT

I noticed that several people is complaining about the half sloper antennas performance and the results are completely different from different users.

I have the sloper for several years. I tested several versions including the big loading coil at the feed point (avoid it) as same as trapped slopers and many others. There are some things that you should know about using any half sloper including the commercial ones.

1. Regardless of what manufacturers claims any half sloper is most effective when it is mounted on a tower/mast at the 30 - 60 foot level (35ft works well for me) and the tower or mast has a large tribander or VHF antennas (at least) on it. This gives the system some top loading.

The antenna grounding under test without the radials

 2. Mounting it on a pole with a lead to ground is not going to get it done and it is definitely not enough to get good performance. I have tried this on occasion and the performance is degraded considerably. Same as mounting it on a tree or on the side of a house even although I will install the grounding wire down to the radial system. You will be able to make contacts, but a low dipole or loop will almost always make similar job or even will out perform a half sloper set up this way.

3. These antennas are primarily vertical radiators and do a decent job on DX at 40/80/160 meters in case of proper installation.

Good grounding is needed (another pipe goes up for beam installation

 4. In any kind of shortened slopers (to get total length of about 15-20m) using big coils the SWR points are about 10-15kHz either side of resonance because it is shortend for that band a lot. My full quarter wave 160 half sloper during short test had about 60% more bandwidth then these shortened ones.

5. The addition of a radial set tied to the tower/mast seems to make a positive difference. I did some testing over the air using 16pcs of 1/16 wl radials and without and most stations report that there was more punch to the signal when using a radial system although it did not always show up on the S-meter. Performance without a radial system is usable however.

Sloper under test without the beams top loading setup

 If these antennas are set up correctly either the commercial ones or a simple quarter wave wire set up as a half sloper will work fine.

If you will not set up it properly, you will be very dissapointed...

73 - Petr, OK1RP

Tuesday, October 18, 2016

The 470Ohms resistors for Beverages...

Hello all,

I noticed that the terminating resistor value and material/type for good working Beverage receiving antenna for low bands DX-ing is never ending story and object of many discussions and internet threads so I decided to post over here few useful information in order to help those guys who do not want to spend annoying time to browse and investigate about this topic.

Why Composition Types?

The important is to look for carbon composition / ceramic composition resistors at 2W power rating at least. The Ohmite has their OY series / 2W for example.


Mouser   10 pack for $16.20

Farnell / Newark:

The resistors datasheet:

It is highly recommended to put a 75V 10 kA GDT in parrallel with the resistor at the end of the beverage antenna. The 10 pack at $1.41 and it will last a long time in the field.


More info links:

Hope it helps,

73 - Petr, OK1RP

Friday, February 26, 2016

W7IUV preamplifier for LB antennas - Revision 5 (built 2003)

Hi all,

as I received several emails with questions about the preamplifier which I am using for my LB external RX antennas like W2PM MiniDiamond loop, EWE loop, K9FD loop etc. I decided to post over here some informations about this unit.

The basic design is inspired with his permission by Larry, W7IUV. The complete article about his preamplifier was published on his web here:


Please read his entire document before starting to build this project. There is data contained within that is necessary to obtain maximum performance from this circuit. Be sure that you downloaded the latest - updated revision.
I started with building this preamplifier in the end of 2002 as Christmas project but I finished it in Jan of 2003. The current version of the W7IUV document was at that time Revision 5 copyright 1998-2009.

It is very important to follow the inctructions for building the preamplifier and use the parts values as described and recommended by Larry in the document.

The size, shape and terminals has been choosen according to my alu-case available...

The most important part of this design in my opinion is the transformer and working state of the transistor 2N5109. You must follow the winding rules as same as core material for transformer and finally you must use prescribed current of the transistor in order to reach expected performances.

If you are interested in the suppliers for Amidon, Fair-Rite cores or even you have problem with finding the 2N5109 there are some links which I used...



The heatsink on the transistor is a must. Do not change the resistors in order to decreasing the collector current of the transistor! These conditions are key parameters for high IMD immunity / OIP3 performance...

Testing the assembled preamplifier is straight forward. Before applying power double check your work. The most common problems are solder shorts and resistors inserted in the wrong place. Once you are satisfied you have correctly assembled the circuit place 50 Ohms terminations on the input and output.
Apply the Vcc terminal and ground. Measure the current drawn with a digital ammeter. It should be 75 mA +/5mA. Remove power and then remove the 50 ohm terminations. Re-apply power and measure current again. It should be the same as it was with the terminations in place. If not the device is oscillating and you need to fix that before proceeding.
Oscillations are usually in the GHz region and are caused by poor layout and/or poor quality capacitors. Bypass caps with very long leads could also be a cause. In fact I used in this version thru hole components but I can recommend to use high quality SMD parts.

With power applied and the specified current being drawn the transistor should be very warm to the touch but you should be able to hold the tip of your finger on it indefinitely. If you cannot either you have insufficient heat sinking or the device is drawing too much current...
If you have proper alu-case then you can use it as the big heatsink.
Final quick measurement in the lab confirmed it's parameters. The gain is slightly lower than expected. Also be careful which power supply you are using. In some cases you can get strange noise from the PSU (mainly switched unit) I am using linear PSU with enough power and proper filtering from AC mains.


Hope it helps.

73 - Petr, OK1RP

Monday, February 1, 2016

CQ 160m DX, CW contest 2016 at OK5T

Hi all,
if you worked OK5T this weekend in CQ160 contest on 160m then there I am sending my operation time schedule from OK5T log...

I was on key as follows:
30Jan16 03:30-06:30UTC
30Jan16 19:15-21:30UTC
31Jan16 04:30-07:30UTC
31Jan16 20:00-21:30UTC
The condx was not as good as we expected. We worked much less US friends and signals were really weak. We used 330m long Bevs to 320/30/90 degs. They wkd very nice even although the VK Bev was so low. (1m up only)

Mr. Murphy visited us when I was on key first morning at 05:00U when I lost NA Bev > stopped work so I was so deaf for last 2hrs of opening to USA. We repaired it during the daylight few hours after. My apologize to all US guys!

We really tried to catch our kangaroos friends in this event too. I am really sorry but no way to work VKs in this CQ160...

I was both evenings on time around 1820-1825kHz. Our VK Beverage sounded also quite well with no usual high noise level.

I really looked for famous Ron, VK3IO and both Steves, VK6VZ and VK6IR. Unfortunately the band was extremely crowded and I am pretty sure that even although we used narrow filters (only IC7600...) our receiver/AGC has been knocked down from so strong nearby signals so I was very deaf even with 330m long Bev to VK.

Well the only single spot I realized on cluster with VK6IR on 1833 on Sat evening but I did not hear Steve unfortunately on this frequency. No VKs readable at our QTH even with Bev to 90deg at all.

As Ron, VK3IO already mentioned on Topband Reflector - http://www.contesting.com/_topband  "This year's contest was almost a total wipe out as far as VK was concerned, due to summer storms on the east coast and the usual topical storms up north and a cyclone off the west coast made it impossible."

Never mind, it is just hobby. I was really happy to work XE2X, YV1KK, HK1X, BA1CW, B1Z. Many thanks for your time and effort and hope to work you soon outside the contest on quiet band.

Many thanks for nice QSO to all members and hope to work you soon again.

73 - Petr, OK1RP

Thursday, January 7, 2016

Stew's 160m BULLETINS by Jeff, VY2ZM

Hi all,

thanks to Jeff, VY2ZM(K1ZM) we are able to go back into the TB history and read the Stew's (W1BB) 160m BULLETINS!

As Jeff posted on the TB reflector...

"Most of STEW's 160m BULLETINS from 1930 to 1965 are on my website in the W1BB section - these chronicle the history of the early TRANSATLANTIC TESTS and were sent to me courtesy of PY1RO. Stew used to send these out to anyone who wanted to be on his distribution list - GRATIS too - just another measure of the man....

They are from his mimeo machine and some of them are a bit hard to read - but well worth a looksee.

The site is K1ZM.com/w1bb



I would like to thank Jeff, VY2ZM for his job and sharing these documents. It is great chance to study the history of the band, operation and other details from 1930 up to now!

best regards,

73 - Petr, OK1RP

Tuesday, December 29, 2015

Friday, October 16, 2015

PreStew here tomorrow...!

The PreStew topband distance challenge will take place from 
1500Z 17 Oct
1500Z 18 Oct. 

This is a CW only event that takes place on 160 meters.  The band has been
coming alive with good solid openings during darkness. 

The "distance" aspect of this is a unique rule where you get more QSO
points for working stations that are further away. 

For example - a station
in Oregon would get 2 or 3 points for working California - 8 or 9 points
for working the East Coast - and 15 or 16 points for working Japan.  VK6 is
worth 30 points!!

Furthermore - if you - or the other station - are running either low power
- or QRP power - the QSO is worth more for BOTH stations involved in the

This unique scoring method encourages and rewards working those weaker
signals - and benefits those who have put a lot of effort into hearing

This PreStew is a warmup for the "big" Stew that takes place on December

Full rules and results of previous events can be found at

Hope to hear you on the band tomorrow night. 
Tree N6TR/7

Topband Reflector Archives - http://www.contesting.com/_topband

73 - Petr, OK1RP