Thursday, November 8, 2012

Can you hear me now!? Kenwood TL-922A

For some time I have had my eye on a few linears, and when this one showed up on eBay recently I could not resist. The Kenwood TL-922A unit was for sale and a weekend trip from Ottawa to Manchester New Hampshire made a safe and enjoyable way to get the unit home.

In the picture below, the amp is shown along side of my father's (VE1JNA - SK) Kenwood TS-850SAT, and these do make a nice pair.

Kenwood TS-850SAT and TL-922A
The TL-922A is a heavy brute coming in at 31kg. Flipping this beast over, when working on it will leave marks on your desk if you are not careful!

The HV supply has two modes which change the plate voltage from 2.2kV to 3.1kV for CW and SSB modes. In SSB mode this amp is specified to generate 1kW out for approximately 80W in. (This is what the curves at the back of the service manual say!)

Call me old fashioned, but if you are like me, then you too believe radios must have plenty of knobs and switches to be interesting. I should add that the metering on the TL-922A also meets my expectations too.  I know analogue meters miss the peaks but there is a satisfaction in seeing the physical needle move as you tune up the amp.

TL-922A Metering

Many folks have commented on the physical build quality of this design, and I will add my comments to the pile-up. I did not confirm when this unit was built, but being of the late 1970's, I can say this 30 year old unit will be here for many years to come because it does not show its age. I was very lucky because the previous owners, and I do not know how many there were, have taken good care of this amp.


Kenwood TL-922A

I have picked over much of this amp from outside and in, and in terms of modifications, there are only a few.
  1. The Tubes are a pair of 3-500Z's from the good folks at RF Parts.
  2. The suppressors are the original Kenwood items and have not been changed out.
  3. The 10M band addition was done as described here
  4. The HV caps have been replaced with Cornell-Dubilier 210uF 450VDC
  5. The SS-100 Universal Soft-Start from Harbach was installed
Thee are two signs of undesired operation, but first I must say that the unit was very clean otherwise. The 1000pf 15kV plate cap, in the center of the image below, has a odd "scar". You can see it in the picture below. The discoloration is highly localised on the edge of the cap, and is "baked on" in that it does not rub off. I am unsure what would have caused this.

Burnt Plate Cap?
The bandswitch was ruined and I had half expected this to be the case. I was able to get a new switch from Multi Tech Industries . Although it took me a bit longer to get it in, it was a easy job none the less. You do have to be careful to make sure every thing gets connected back to where it started.

Installed Multi Tech Band switch
Interestingly, the amp was able to run on all but 20m. A close inspection of the 20m input filtering led me to a pair of mica caps that had been pushed against each other. This caused their leads to cross and touch, shorting out the inductor. Simply fixing this, made the input SWR drop from over 100:1 to 1:1 and 20m was now in business too.

Shorted input filter for 20m

As an example, operating on 40m, the setup below shows 55W in and 650W out. The plate and grid currents are 450mA and 150mA.

55W in and 650W out

Having only had the amp for a few weeks, I know this is going to be a good addition to the shack. If you are in the market for a this piece of Kenwood history, I hope you are able to find an Amp as well cared for as I was able to.

MHz       1.8    3.5     7     14     21    28
Band      160m   80m    40m    20m    15m   10m

Plate     3.5    7      7      14     21    >21   
Load      0      1.8    2.2    4      4.2   4.8
Ip (dip)  Yes    Yes    Yes    Yes    Yes   Yes
Ip        480    500    500    500    500   350   (mA)
Ig        200    150    180    175    150   150   (mA)

HV       1900V  1900V  1900V  1900V  1900V  1900V  at load

Pout      550    600    700    800    625    435   (W)
Pin        65     55     75     70     55     40   (W)
SWRin    1.5:1   1:1   1.3:1   1:1   1.3:1   2:1


Sunday, October 21, 2012

VE3IAC/2 et l'île Verte


IOTA NA-128 is an island group in the Quebec province of Canada in the St Lawrence Seaway. IOTA indicates that this island group is well claimed by 43% of participants. l'île Verte is one of many islands in this group which includes a 350km stretch of the St Lawrence Seaway.

NA-128 Island Group
With your help we completed 153 QSOs. My thanks goes to all who answered my "CQ de VE3IAC/2 IOTA NA-128" call. I realize that pileups can be hard to get through, and I appreciate your patience.

From a volume perspective, notable QSOs are all of those from Europe and Middle East. I am always amazed how many operators there are in Germany.

New for me was Iceland, Aegir Olafsson TF2CT, many 73s to you.

Noel Hammond ZR6DX of South Africa at 12600km was especially nice, 599 both ways.

I must not forget 9000km South America stations in Argentina Horacio Cortadello LU6EHO and Dani Grezzi LW1DG.

The operation station included a Yaseu FT2000D Transceiver running 200W SSB through a Palstar AT1500CV Tuner into a twin lead fed DX Engineering 80m Doublet. 50watts was run on 10m and 20m with a YP-3 Portable Yagi .

VE3IAC/2 Operating Station at Ilse Verte NA-128
The station also used a Icom 756 Pro III Transceiver running 100W SSB through an Icom AH-4 Tuner into the twin lead fed DX Engineering 80m Doublet.

VE3IAC/2 Operating Station at Ilse Verte NA-128
YP-3 setup for 10m Operation
The view facing Europe.
Lighthouse on the North Shore

Here is a link from the last time we were here.

73 OM

Monday, February 27, 2012

2012 Silent Lake DX expedition


Thanks for visiting, this post is for another trip to Silent Lake. This trip was especially nice for a few reasons. My work takes me away from home on occasion, and I had just returned from Stockholm. Roxanne and I love time we spend together and this was a nice way to slow down a bit and enjoy each others company. On the other hand, the real reason, (but don't tell her!) is that I get to play radio once again.

Silent Lake is a provincial park in the central south Ontario. 

This park has a number of Yurts for daily rental, more information on these can be read at . The more notable items that are provided by the park at each Yurt are;
  • Two sets of bunks beds, sleeping 6 or more (depends on how cozy you want to be!)
  • Heating is by wood burning stove, with a endless supply of wood that splits very easily 
  • Propane barbecue, this is truly nice.  

Entry into the park, starts with your personal vehicle but does not end there, because you can not drive to the yurts, even though the yurts are on the normal campground road system. The park Ranger takes you and your stuff the last 1 to 2 km into the park with a ride in a mini bombardier and a pair modified sleighs.

At the site we were welcomed the next morning by a doe and her two yearlings. The park ranger  had told us that there was a threesome that was wandering the park, but for the past few days, they had not seen them all together. It was nice to see that nothing had happened to them.

I'd have to say with ears like those there is no wonder you only see them if they want.

 On the radio front, the important bits of the setup was the usual stuff.
I would expect that most folks are familiar with the IC-7000. I like the radio very much, it gets a bit hot at times and can use a bit of extra cooling at times. This is simply done with a 3in muffin fan.

IC-7000 100W Transceiver
The AH-4 tuner is another cool (especially in the winter time!) piece of equipment. It connects to the IC7000 with two connections. RF coax, and a 4 wire control link. It is activated, and powered from the IC7000. I have used this unit for both random wire end fed and in this case feeding a balanced system.

Icom AH-4 Tuner

The antenna I have used on this trip as well as a few others is a 80m doublet. It is twin lead fed (about 90ft) to the main part of the antenna which is about 130ft in total length. The connection is a bit different from the usual description in the manual which focuses on unbalanced feed lines. I am sure there are other ways to do this but, in this case, the balanced feed line is attached across the tuner from the "Hot" connection and the ground. A choke is on the feed line to the rig, this unit is from MapleLeaf. The tuner is not grounded, as it would be when driving a end fed system. There is no set of ground radials either. This makes this a nice and simple setup. It tunes up any where 80m to 10m, SWR at the rig was usually 1:1. Gotta love that!

80m Doublet (feed line at least)

Back inside, the radio is powered from the battery booster, which takes the voltage of the batteries that droops as they are discharged and provide a rock solid 13.5V under tx load. I can say that, I know this is a switching supply, and these can be nasty for birdies. But this unit has never given me problems, even in this place where the noise level is S0 when the bands are good! This unit is not large and is triggered by the TX RF and provides boost only while TX. I imagine this is why on RX there is no noise. Very smart design I suppose.

Battery Booster

The actual battery plant is four 50AH gell cells. These are charged up at home and used for the duration without any additional charging. With 200AH, the rig draws about 20A at 100W, but perhaps 8A at 25W so I'd guess there is 25Hrs TX key down time, that must easily translate into days of operation time. I have never run out of juice. The laptop is powered from the same plant, but I use a 12V laptop adapter, The goal was to avoid a 120V inverter, and one less thing to take along.

The Batteries

The whole thing ends up being the "Silent Lake HF Station".

The Silent Lake HF Station

Now, for the operating, well it was very good for a portable setup, and QSOs were truly global.

The best contact of the trip, was to Frank Schoombie's South African station ZR6RC. This was done on 15m, at mid day, in BPSK-31 mode. He answered my call and I almost fell off my chair. I would imagine this QSO hit the water a few times making its way nearly half way around the world. Thanks Frank for being there.

Now, the next new thing for me was to notice that ONTARS needed a controller Tuesday afternoon in the 2PM slot. With some reservation, I threw my call in the hat and away I went. You can see may name there at 2PM, as soon as Barry ISX updated the ONTARS website I knew there was no turning back!

Well, the hour went very fast and I was pleased it went well. I did not run out of power, I did not make to many mistakes, and most of all it was a blast. I enjoyed answering the many questions that helped folks understand where I was and the station setup.


I know there was one check in I missed to log at the start and for this I am truly sorry.  Thanks to all who checked in with me.

  • VE3CAK    John
  • VE3ISX  Barry
  • VA3ZW     James
  • VE3FAS    Philip
  • VE3NJV     Nick
  • VE3ODT     Don
  • VE3GGP     Harry
  • VE3ZP     Pat
  • VE3XDJ     Rich
  • VA3HRH     Handiradioham Amateur Radio Club of Canada
  • VE3BWQ     Allan
  • VE3UFO     John
  • VE3MDL     Marcus

I guess I better press the "Publish" button on this post. I look forward to the next DX expedition in the heart of Ontario or other place, and look forward to seeing everyone again.


Below is a post of a previous winter DX expedition is at the link below.