500 Khz signal generated

The 500 KHz transmission path works. I mixed the LO signal with a 4,433 MHz signal out of a simple xtal oscillator. The mixed signal is filtered by 2 455 KHz  IF filters. It was easy to tune those to 500 KHz.
So the transmission path works for CW. I also improved stability of the LO.
Next step is to make a IF amplifier for the receiver.

Quicky for 500 KHz

I am building a small 500 KHz transceiver. It will be simple using stuff from the Junkbox. I expect that it can be build quickly.

It will be a simple super with 4.433 KHz As IF. The  local oscillator will be 500 KHz lower. I found 2 xtals that can be used to generate signals  3.93 KHz  apart. A NE602 Mixer will be used to mix those signals. The wanted 3.93 MHz signal can be filtered out using a bandfilter.

The IF strip will be based on the bitx 20 concept. I will use a Mc1350p as  IF amplifier. Building AGC is not difficult using this amplifier.  It will be suitable for SSB so I can use WSPR.

Current status:
Xtal oscillators and mixer are ready. Some fine tuning needs tor be done though.  

 

4 Meter in the Netherlands

Today I read on the VERON side that we may get access to 4 meter. 70 to 70.5 MHz to be precise.

That would be great. I am thinking about building something for that band. I could use a transverter and my 50 MHz transceiver. I could use the concept of my CB to ham transverter. The xtal frequency can be a fixed, no need to make it tunable.  alternatively I could make a transverter for a CB radio.

Design idea 1: Use 50 MHz transceiver. Make a xtal oscillator at 20 MHz. Xtal for frequency is standard. Mix with 50 MHz using a SBL-1 mixer. Some filtering is needed at the input. I am sure a preamplifier is needed as well. This makes a basic transverter. Then the output power must be boosted to 8 watt PEP. A power module can take care of that. I found a few on Ebay.

Design Idea 2: Use CB radio and a transverter. It looks like design idea 1. However the Xtal frequency is 43 MHz and it should be tunable over 20 KHz.  This 43 MHz is not available as  standard Xtal so I may have to mix 2 Xtal signals to get to 43 MHz. Maybe 25 MHz and 18 MHz.

cb collection

Here some pictures of my collection of CB radio's.  Most of them  are working.
Some of them will be modified for use on Ham bands. Some others will be stripped for parts.

9 MHz IF strip

I am working on a IF strip for a new homebrew HF transceiver.
Some of the design goals:
-SSB/CW
-Variable IF filter width.
-Noise blanker
-AGC fast and slow.
I am building in a tin box. The components are mounted on the tin bottom of the box.
Currently the IF filters an the IF amplifier for RX are working. A picture will be posted soon.

The new HF transceiver will be described in a new blog dedicated to the project.

some activity

It has been a long time since the last entry. Ham radio activity is limited at the moment.

One of my small projects the small projects is a 137 KHz  /500 KHz generator. I have a old 27 MHz transceiver that was stripped for parts. It is still working though. I have wired it to transmit continuously.
I plan to make a digital signal out of it. Then it can be divided digitally to get 137 KHz and 500 Khz.
This can be done by small module inside the CB radio.

wire through pulley

I have a small mast with a 2m/70cm antenna on top of it. On top of the mast a pulley is mounted. It is used to keep a wire antenna in the air. This wire antenna was connected to a non conducting wire. Unfortunately the isolated wire broke so my antenna came down.

I already mounted the wire to the top of my chimney. However I want to use the pulley for a different antenna. So I had to find a way to get a wire through the pulley again.

Last night I succeeded. I took a 2 meter long tube. I pushed home electricity wire through that tube and through the pulley. When enhough wire was pushed through I connected isolated wire to the electricity cable. Then I pulled back the tube with the wire. This pulled the isolated wire through the pulley.

ic730 rx preamplifier relay problem

One of the know problems with the good old IC-730 is a non working preamplifier relay. The relay does switch but no difference in signal level is heard. The problem is dirty contacts in the relay. I found some solutions on the internet. I suppose they work but I did something more simple.
-remove transparent plastic hat of relay. Do it gently it looks like it can break easily
-turn on radio
-turn of preamp
-put some wodka/alcohol on a piece of paper. between the contacts
-turn on preamp
-gently move paper around.
-turn off preamp
-remove paper
-mount plastic hat

I have cleaned it this way 1.5 years ago, the preamp works without problems since.By the way, when using a 2x13 meter dipole antenna the preamp is not needed at all. Not even on 10 meter. When the antenna is connected the noise increases significantly.

500 KHz and 137 KHz

Hopefully we get an allocation around 500 KHz. It seems to be an interesting band. At the moment a few hams are permitted to use 500 KHz on a temporary base. I was too late to apply for a license.

Nevertheless I start building an synthesizer for 500 KHz and 137 KHz. When it is ready I can use it for a 137 KHz transmitter. And hopefully for a 500 KHz TX too.
What I have here is a PLL synthesizer that works from 5 MHz to 5.5 MHz. It has TTL output. It was intended for a HF transceiver project. It works but it produces to much phase noise for a receiver. For a transmitter it is good enough though. Especially when when frequency is divided.

For 500 KHz Dividing is done in 2 steps. First divide by 5 then by 2. The divide by 2produces a signal with 50% duty cycle. That is important for the power amplifier.

For 137 KHz the divided by 5 signal is divided by 8.

I made a small print for the dividers. It works, the signals sound good on a HF receiver. A picture will follow soon.

160 meter

I received my 160 meter CW signal on websdr twente.The signal was not strong S7. Maybe the new antenna layout helped. The test was performed in the middle of the night using 80 Watts. It must have been skywave propagation as the distance is over 120 km.
Now I hope to make some contacts on 160 meter.

Transmitter using tuner

At a flea market I bought an old PLL tuner. I wanted to know if the synthesizer could be used for hamradio. It had to be an old one as the new ones use a everything on on chip approach. I suppose the synthesizer is unreachable in the new tuners.

Plan was to use the synthesizer for the FM band. Mix this signal with a signal out of a VXO at 98.7 MHz. then filter it using a lowpass filter at 20 MHz. This would make a 0-20 Mhz signal generator. I listened to the signal of the synthesizer in cw mode to check the quality. Unfortunately It does not sound like a T9 signal.

I also listened to the signals out of the medium wave synthesizer. This signal sounds T9. The synthesizer can generate a signal in the 160 Meter band. Stepzize is 9Khz. I could make a AM transmitter just for fun.

fixed antenna

One of my trees had grown into the wire dipole antenna. It had a big effect on the antenna especially during rainfall. So I cut some of the branches. Unfortunately one of the support wires broke. It turned out that the weather had weakened it. I could pull it apart by hand easily.

So I climbed upon the roof to connect the wire antenna to the chimney. I suppose the antenna works beter now. Previously 4 meter of the wire ran parallel to the metal VHF/UHF antenna pole. That is not ideal. I did not make a qso using the new setup. So I don't know how it performs. I did found out that the antenna tuner needs different settings.

Coax balun 1:4 for open line fed dipole

My antenna tuner is a asymetrical tuner. I want to use it for my dipole that is fed using open line. So I need a balun. I made this one PA0FRI coax balun

Instead of 3 meter coax I have use 5. I did this to make it work on 160 meter.
3 meter is recommended for 80 meter and higher.

My antenna is an compromise. It consists of 2x13 meter dipole fed by 14 meter open line. The dipole is folded to fit in my small (15x5 meter)garden . Inside the house the open line is connected to the balun. The balun is connected to tuner by 5 meter RG213coax.


The antenna should work for all HF bands. It does, even on 80 meter. I checked uing the websdr located in twente. Just 3 watts was enough to produce a clear CW signal. Even 1 Watt produces a audible signal. The distance Tilburg Twente is 134 km.

Previously I used a hf choke made of coax instead of the balun. It is hard to compare the choke and the balun. The balun should work better but only time will tell.

I hoped I could produce a usable 160 meter signal using this antenna and the balun.
Unfortunately it is not going to happen. Although the reception on 160 meter has improved dramatically compared to the RF shoke, the signal is hardly readable on the web sdr in Twente. It is not even readable on the websdr in Eindhoven. Not even when 100 Watt is used. Eindhoven is just 40 km away from Tilburg. I can tune the antenna to 1:1 easily.Unfortunately the power is converted into heat inside the tuner. It gets hot.

loop antenna 160 meter

This is a loop antenna for 160. It is based on a design from SMOVPO. I have changed the dimensions though. Capacitor is 1-50p. Wire is remaining antenna wire. Pickup loop is made of solid 220V domestic electricity power wire.
The construction is not suitable for outdoor use.



It can even be used for TX. Five watt is possible. Sparks occur when more power is used. SWR 1:1 when tuned properly. Reception on the loop is way better than on my 20 meter long dipole. I knew loops can be great RX antenna's.Still I was surprised by its performance.

start of blog

In this blog I will describe my ham radio activities.
For some of my bigger projects I have created separate blogs.
However It would be unpractical to make a blog of all smaller projects.and activities.
Those are described in this blog.