I’m slowly getting into CW at the moment and have started with some SOTA CW chases. I’m using an ICOM 718, which is not equipped with CW filters. When the activator is “alone” on a band, I manage fine. However, when the activator is transmitting on a crowded band like 40m, it becomes very annoying to listen to, especially with 2 or 3 loud stations nearby. It’s overwhelming, and I end up turning the radio off. This got me thinking about getting a CW filter.
Option 1
Buy a second-hand official 250 or 500 Hz filter, such as the FL52a or FL53a. These are hard to find and expensive—around €200 from the US. For a €400 radio, it feels a bit excessive.
Option 2
Build my own audio filter to place between the radio and the headset. The Variable Bandwidth Filter Module SSB/CW from Sotabeams is only €45 and quite appealing. Another option is a classic passive LC filter (example here), which could be very cheap if I can build the inductor properly.
Option 3
Sell or retire the ICOM 718 and buy an amplifier for my TX500 portable radio. The TX500 has a great receiver, lots of filters, and would address the issue. Financially, it could be a neutral operation, but I’d lose a radio in the process.
I don’t know the difference in performance between embedded IF filters and “post-radio” audio filters. I’m really not an involved chaser; I just want a solution to limit the QRM. It doesn’t have to be top-notch.
Are they a lot better than audio filters ? From what I can see, my only option for them is eBay US , at around 150€ + probably 50€ shipping costs. Not cheap.
An ICOM 7300 would be great but it means selling the 718 and adding an extra 600€ to get it second hand. Truly excessive for the few minutes I spend on the radio every week / month.
I think I’d start with this option. It will almost certainly help, and may solve your problem completely. You will also have fun making it, and the enjoyment of using something you have made.
If it is not good enough, you will have learnt something and lost nothing
As a person just getting started with Morse this might be biting off more than you can chew, but a zero-cost Option 4 would be to train yourself to distinguish signals of different pitches coming through the wider filter.
There is old, free Windows software called Morse Runner that could help with this. And I recently learned of a newer free web-based practice tool called Morse Walker https://morsewalker.com/
With Morse Walker you can use the “Basic Contest” mode and under the Responding Station settings, adjust the number of simultaneous calling stations as desired.
I’ve used a Sotabeams DSP audio CW filter with my FT817 for activations and found it very effective. I didn’t like all the leads (which was part of the motivation for homebrewing my rigs) but this doesn’t matter for a shack setup. One issue to be aware of is the AGC will act on any signal in the SSB passband even if blocked by the CW filter so you may have to turn off the AGC.
I would understand you, if you were in a contest like WPX or CQWW or if you were the operator of a DXpedition.
My recommendation is “Avoid using filters” unless it is practically impossible.
Why don’t you try playing with the RIT, CLAR or the encoder?
Even though I bought the Icom IC-705 last year, I never used the filters and I assure you that in Japan the 7mhz band is pandemonium all day long.
I’m not saying don’t have a filter, just avoid using it. This will help you be more attentive and have a sharper ear.
You are probably right but I have very sensitive ears and even with a top quality headset, the sound not so loud, my head is about to explode after a few minutes. I’m using ear protection even when I hoover the floor, just to say …
I tried but no success. It’s just moving the bandpass up and down and when I get rid of a qrm signal I just gather a new one on the other side. Maybe I’m doing wrong but holly banana it’s a killer
Je veux savoir si ça vaut le coup de payer un filtre quartz relativement cher (la moitié du prix de la radio !) ou si un filtre audio dsp fait sensiblement le même travail pour une fraction du prix.
@F4LEK
If you decide to buy and you are faced with a choice of CW Filters if I couldn’t have both and it was for SOTA /P operation I would always get the 500 Hz one. I find the background noise listening to a 500 Hz filtered background is far easier on the ears than the bandwidth noise produced by a 250 Hz filter. I am prepared to tolerate the wider skirt from the 500 Hz on reception, as my ears provide me with sufficient filtering to pick out the signal of interest.
I’m not fond of audio filtering for CW. I’ve tried several and I don’t think its particulary effective as earlier in the thread as @MM0FMF also noted…
