Band Switch
The TL-922 band switch copped a bit of a hammering especially on the higher bands on tune up if not loaded properly, or in situations where the aerial change over relay disconnected the antenna before drive was removed. Whatever the cause, when tank circuit voltages spike, you might have a case where the band switch arc’s over.
Multi-Tech, a US manufacturer, made outstanding replacements. The Multi-Tech switch for the TL-922 was in their 80 series, and the specific part number was R802G1130003.
I replaced mine and found that the install was actually easier than I thought it would be. Initially, it was a job I was not looking forward to. Being larger, and it having go into the same spot, meant that it was going to be a tighter fit, right? Just working through it slowly and patiently it all came together nicely. Don’t be put off … it was straight forward.
What makes the Multi-tech switch so good? Take a look at the photos.
From the front the new switch is substantially larger then the original Kenwood switch on the left.
Now looking at the business end, (the Multi-Tech switch is now on the left) Notice the blue arc shields. What a great idea to improve the switch in an RF application.
- The quality is excellent
- It has a ceramic former for each wafer
- Silver plated contacts
- The spring pressure on the contacts is higher
- The blue shields are corona or arc shields
- The arc shields increase the rating to 7.5kV
In the following two photo’s, the first is JH2CLV’s installation in his amplifier, and the 2nd is the install in my amplifier.
I am not sure if Multi-Tech is still in business. I say this because their web site is no longer active. I did find that they seem to still have a Facebook page. I have included their details and I truly hope they are still in business as this is a highly recommended upgrade. I am sure that anyone who has already fitted the switch to their amplifier would also agree.
https://www.facebook.com/MTIINC1/
Multi-Tech Industries
64 South Main Street
P.O Box 159
Marlboro NJ, 07746
Phone 732-431-0550
Fax 732-761-0573
If Multi-Tech are no longer manufacturing, then it becomes much more difficult.
One of the most complicated I have seen is what Roberto IW1PUR was forced to do. It is also interesting to note that Roberto also believes that if he had changed his aerial change over relay earlier, then the band switch failure would not likely have happened. Roberto is not blaming parasitics, rather the hot-switching of the slow antenna change-over relay allowing high voltage spikes.
Image credits: JH2CLV, VK3BBQ and IW1PUR