RadioBanter - HF band scope???

Bruce W.1 wrote:
DX will soon be upon us. This time around I'd like to have a band scope,
without spending thousands of dollars. This so I can see band activity on
a display screen. For this I have not found a solution.

The cheapest solution that I have found is an Icom IC-PCR1500 PC
controlled receiver, for about $500. It would do the job.

My Icom IC-735 HF rig does not have an IF output on the back.

I recall seeing standalone band scopes, but I can't seem to find any now.

Can anyone recommend a solution?

Thanks for your help.

Hi Bruce,

I've been using a Heath SB-620 "Scanalyzer" for about 20 years (Yaesu made a
similar unit, the rare YO-901 w/ bandscope option). The Heath units can be
found for around $100. I used mine with a Heath SB102, and now with a
Kenwood TS-130S. My SB620 came built for the Heathkit IF of 3395KHz (I
didn't get the parts for other IFs). When I ran the SB102, that wasn't a
concern. But, when I switched to the TS120S (and now TS130S) with their
8830 KHz IF, I needed to come up with a way to make it work. The first was
to tap off the rig's IF at the mixer (before the crystal filter) w/ a simple
buffer amplifier, and feed it to the ACC socket via some small RG174 coaxial
cable.

In looking at the input amplifier of the SB620, I saw that it could be
configured as a mixer with the flip of a switch. I would need to supply a
signal to mix with the IF signal from the rig (e.g.: 3.395 + 8.83 = 12.225
MHz). I built an oscillator (dead-bug style) using a crystal meant for an
old 2M rig (146.76 / 12 = 12.23 MHz ), plugged it in to the SB620, and
tweaked the 620's sweep oscillator inductor just a tad. Voila!

The first thing I noticed was the difference in how far I could sweep. With
the SB102 et al, you have a preselector which limits the bandwidth you'll
see at the mixer output. About ±50 KHz was the extent of the response.
However, with the TS-120/130, there's a bandpass filter at the frontend. I
can sweep the entire band. The limiting factor is the width of the CRT...
the blips become VERY close together. hi!

According to the service manual, your '735 has a 2nd IF of 9.0106 MHz, and
you'd pick off the signal at the output of the 2nd mixer on the 'Main Unit',
ahead of the IF filter(s). Short of having a standalone spectrum analyzer
or receiver w/ Panoramic Display, this is your best bet.

vy 73,
Bryan WA7PRC