As mentioned elsewhere on this site I am the proud owner of an Acom 1010 linear
amplifier.
I would say that Acom amplifiers deservedly have a good reputation for quality
and reliability. However, I have had an issue with mine and after seeking
advice via email from Acom I have been able to repair it satisfactorily.
I am embarrassed to say though that I have experienced the exact same issue
three times now. The first time I would say was a simple mistake but the
subsequent two were caused by me not learning from the first!!
Symptoms
The amplifier powered up and went through the start/warm up entirely normally.
On keying the rig and applying RF to the amplifier the amp switched to TX but
there was no RF output from it at all. Receive was OK as was transmit when
the amp was powered off. Upon investigation and having the cover off the
amplifier I could see no readily visible signs of any issue.
Although I had purchased the amplifier second hand from a reputable source any
warranty period provided by them had long since expired. I decided to
reach out to Acom for some assistance and sent an email describing the symptoms.
My email correspondent at Acom advised that he believed that the issue lay with
a RFC on the wattmeter board. Removal of the cover over that board
verified that. There were visible burn marks on the inside of the cover by
"RFC1" and corresponding evidence of burning on the choke itself.
Visible burn mark.
Wattmeter board RFC1
The Fix
After a payment of the required amount and providing delivery details a
replacement RFC was duly received from Bulgaria. After removal of the
wattmeter board the replacement of RFC1 was quite straightforward.
Once the wattmeter board was re-installed the amp was back to normal operational
again.
As I said earlier I am embarrassed to say that I have had the same issue a total of three times now and the second and most recent time I have rewound the RFC myself rather than purchasing a replacement from Acom. I had the original choke, stripped off the burnt wire and wound 52 turns of 0.35mm enammeled copper wire (approximately 2m) on the core to form the replacement choke.
The Cause
My setup consists of my FTdx101MP connected to the Acom 1010. The output
from the amp then goes to the input of my Tokyo Hy-Power HC-2000 atu and then to
the antenna/s. My primary antenna is the EFT described elsewhere on this
site and the rig's internal tuner will find a match on most bands.
Although I generally use the HC-2000 to match the antenna I have used the rig's
atu from time to time instead, but only when not running the Acom.....probably to save a few precious seconds when
having heard something "choice" that I wanted to get in my log. So, in
that case, although the rig was seeing a match the watt meter board in the amp
would still have been seeing a high SWR and there, I believe, is the cause of
the problem.
The Cure
There are two options here.....
1. Remember to always use my HC-2000 matching unit to allow the rig to see a low
SWR rather than the built in atu or
2. Re-connect a switching unit that I built after the second time I had this
same problem!! The switching unit is very simple and I will describe it
along with photos on a separate page. Very simply the unit bypasses the
amplifier so the rig's output goes directly to the
HC-2000. When powered up the unit redirects the rig output to the input of
the Acom and the Acom output to the HC-2000.
A Word of Warning
If you are using an Acom 1010 in a similar fashion (ie inline but not always in
use) always ensure that you get an antenna match using your atu even if the
rig's internal tuner can make it. Even at modest power levels I think you
could risk the same issues.
As an aside and relevant to the above I did confirm with Acom that running 200
watts from the rig via the amp powered off or in "standby" was OK.
