06-02-2022, 07:50 PM
Hi Doug
As the manufacture has still not responded to or acknowledged my enquiry from more than a week ago. It seems they are no longer interested in offering any assistance.
The ATU in question is a SGC 235. – Reputedly the “Mack Truck” of all ham ATU’s. From my experience thus far. It is actually a “Dinky Toy”
What I am attempting here is a direct substitution
ie- removing a Icom AT140 from a working system and replacing it with a (supposedly far more capable and robust) SGC235 – no other changes.
At the moment I don’t have any RF Caps. I could do the inductor. But today I am pretty browned off and I am done with the whole deal. This has consumed an inordinate amount of time, energy, not to mention considerable amounts of money on something that should be almost a plug and play installation.
Yesterday I pulled the second 235 out and replaced the burnt relay by cannibalizing a working relay from the first 235 board. After replacing that faulty relay and re-installing everything. The 235 functioned. I then set the TS480 to tune at 20 Watts max. By the published specs the 235 can supposedly take up to 100 watts at Tune. I wanted to give the 235 enough power to tune & lock correctly. I put the Power SWR meter in line and went from 3.5 Mhz to 28 Mhz in 0.5Mhz steps testing the 235 against SWR. It tuned perfectly across that range with a couple of peaks. A couple of times I had to force a re-tune but each time it re-tuned with a better solution. The most pronounce peak at 26.5 Mhz was a max of 1.8 – 1. The overall performance was excellent.
I then put a contact thru to the SailMail station in NSW on 12 Mhz and uploaded a test message. (The previous SWR tests gave a SWR at 12 Mhz of 1.09 and 1.05 at 12.5 mhz) The signal strength was very low with a lot of QRM and it took a lot of time/attempts to transmit the data. During the contact the SWR did not waver. The TS480 is set to 100 watts. The link initiates at 100 watts and once established drops to ~ 50 Watts. So the 235 was doing much of it’s work at ~50 Watts. I then tried a Winlink station VK6KPS on 7 Mhz but had no response. I then tried VK6KPS again on 10 Mhz. After less than 10 seconds the SWR started to waver and I shut everything down immediately. That looked exactly like another burnt relay.
Today I took the cover off the 235. There is no apparent external heat damage on the relay K14 plastic cover. Maybe with so much practise I was able to shut it down before it burnt thru the Relay plastic cover.
At this point I think that I must accept that the SGC 235’s will not work where the Icom AT140 will.
Mike
As the manufacture has still not responded to or acknowledged my enquiry from more than a week ago. It seems they are no longer interested in offering any assistance.
The ATU in question is a SGC 235. – Reputedly the “Mack Truck” of all ham ATU’s. From my experience thus far. It is actually a “Dinky Toy”
What I am attempting here is a direct substitution
ie- removing a Icom AT140 from a working system and replacing it with a (supposedly far more capable and robust) SGC235 – no other changes.
At the moment I don’t have any RF Caps. I could do the inductor. But today I am pretty browned off and I am done with the whole deal. This has consumed an inordinate amount of time, energy, not to mention considerable amounts of money on something that should be almost a plug and play installation.
Yesterday I pulled the second 235 out and replaced the burnt relay by cannibalizing a working relay from the first 235 board. After replacing that faulty relay and re-installing everything. The 235 functioned. I then set the TS480 to tune at 20 Watts max. By the published specs the 235 can supposedly take up to 100 watts at Tune. I wanted to give the 235 enough power to tune & lock correctly. I put the Power SWR meter in line and went from 3.5 Mhz to 28 Mhz in 0.5Mhz steps testing the 235 against SWR. It tuned perfectly across that range with a couple of peaks. A couple of times I had to force a re-tune but each time it re-tuned with a better solution. The most pronounce peak at 26.5 Mhz was a max of 1.8 – 1. The overall performance was excellent.
I then put a contact thru to the SailMail station in NSW on 12 Mhz and uploaded a test message. (The previous SWR tests gave a SWR at 12 Mhz of 1.09 and 1.05 at 12.5 mhz) The signal strength was very low with a lot of QRM and it took a lot of time/attempts to transmit the data. During the contact the SWR did not waver. The TS480 is set to 100 watts. The link initiates at 100 watts and once established drops to ~ 50 Watts. So the 235 was doing much of it’s work at ~50 Watts. I then tried a Winlink station VK6KPS on 7 Mhz but had no response. I then tried VK6KPS again on 10 Mhz. After less than 10 seconds the SWR started to waver and I shut everything down immediately. That looked exactly like another burnt relay.
Today I took the cover off the 235. There is no apparent external heat damage on the relay K14 plastic cover. Maybe with so much practise I was able to shut it down before it burnt thru the Relay plastic cover.
At this point I think that I must accept that the SGC 235’s will not work where the Icom AT140 will.
Mike