Heathkit HA-14 Restoration thread

This thread will detail the Restoration of the HA-14 KW AMP scored at Dayton this year
along with the construction of a Homebrew HP-24 Power supply

SO just what will I DO with this HA-14? It will be much lighter and compact to carry around to Operating events such as we had recently at FRYS. with a KW I should be able to break a few pileups

Modifications to the HA-14: Set up for soft keying, and fans to cool the 572Bs
Both mods will be housed in a mating underplate so that the HA-14 remains CHASTE

One big problem I have with the HA-14 is no LOAD CONTROL. that means I will hafta incorporate a HIGH POWER TUNER into the mix so the amp will be happy with a 50 ohm load.

The HP24 will be built on a open frame like I did on the Homebrew HP-23 I built awhile back. using Home Depot angle aluminum and bars. Then thin aluminum plates will be bolted onto the sides to enclose it. I don't see a need to make a top cover like the original HP-24 had other than to cover the exposed resistors on the Cap PCB. They are at HV levels. Safety is paramount.

One problem is the HV cable assembly. I see the connectors on Ebay but they are at $15 each so that would be $60 just for set of 4! Plus the cable!!

I already miss the California Electronics JUNK STORE where I used to score most of my needed parts for homebew!
The key to the whole project is the SB-200 Transformer I need for the HP-24. I hope Sue will decide to let hers go. NAME YOUR PRICE! Money is not an issue!
I looked for junker SB-200s at Dayton but none were found. It would cost almost as much as the XFMR is worth just to ship it from anyplace in the world!

Here is basic layout. The fan will blow hot the hot air up through the HA-14

 

I had one of those back when I was in college. I was able to scout up a power transformer from a scrapped SB-200 and made a HP-24 clone. That little amp will do 600 watts out without blinking! It gets hot! A fan blowing up is a good idea, the cabinet will pass air.

Pete

 

Looking forward to this thread!

 

eWe will have to discuss the details later this week regarding the transformer, I know where it is in the garage, I'll have to drag it out and look it over...

A better alternative for an enclouser would be to get one of those die cast housings made by Hammond.
They do make aluminum ones large enough to mount the transformer on.
As I remember you can get them up to three inches deep. More than deep enough to contain all the components under chassis.

 

Just be careful with those HV connectors... it is easy to reach behind and think you're removing a PL-259 by mistake. That power hookup is a bit scary for any amp. I got flung across the cellar when a pin hole in the HV cable entered my right hand and exited the left... I saw stars; almost didn't make it past 20 yrs. old! But, it ingrained a deep respect for HV; and not letting one's guard down.

Pete

 

Those connectors are fine for internal connections but they make me nervous when they are used externally.
The other issue I have is related to providing a good solid chassis to chassis connection.

 

today I worked on the HA-14 as gotten from the Hamvention. It came with 2 new 572Bs but not installed. FOR SOME Reason U can't put the tubes in the sockets as explained in the Heathkit manual. Maybe these CETRONS are longer than the ones Heathkit supplied but I had to remove the tube retaining brackets and loosen the side holder and physically tweak the bracket to get the last tube in. It is not POSSIBLE to put the tubes in after the unit is all assembled without doing some serious disassembly!


so I don't know how the ones that were in there were removed. Maybe if the they were broken they could be pulled out.
Next I pulled the front panel and cleaned it up and removed the meter. Upstairs I found another Heathkit Meter that was sacrificed just for the front cover, which had yellowed beyond repair. Once plastic yellows this much it is hopeless. Sanding it down will not remove the yellow so my wonderful plastic repair won't work! NOVUS won't help either.
I found a the correct color of Heathkit knob upstairs and replaced the wrong one. The bandswitch is really tight and great amount of torque is required to turn it. I have seen this in other Heathkits , sometimes the switch is frozen up beyond repair! It seems to do with the front of the switch and not the wafers. But I can turn this if I really strain my grip. The rest of the amp seems in perfect condition. I did find a HV cable upstairs in the debris (I have about 500 boxes of junk stashed upstairs the boss doesn't even know about. Some day he will go up there and have KITTENS!!!
"WTF IS ALL THIS??!!!! GET IT OUT OF HERE!!!!!!!!!!!!!!"
I was looking and have all kinds of Heathkit parts almost enough to build more SB-101s and 301s and 401s. Just need a smoldering hulk chassis to redo.
The HV cable has the correct MILLEN Connectors on it so all I need is the Chassis connector which KE9PQ has for about $15. I know I have seen these in boxes of junk at the swapmeets, I should have scarfed them up!
going to be painful to pay $15 for one of these when I know I could have had one for a NICKEL!!!


SO here is the HA-14 ready for service once I get a PS BUILT


Now going up to the JUNK STORE NEAR HRO to pick up parts for the PS. I will order the caps from MOUSEY WOUSER and then on HRO to get my FREE DONUT

 

Another thing I will be adding to the Power supply is DC Metering. There is no HV DC meter on the HA-14 like the SB-200 has or Plate current. Guess there is no way to monitor the grid current.

 

went to the junk store in Kearney Mesa near HRO but they were closed today!!! Maybe they decided to take off all Memorial Day weekend! Won't be able to visit them again till some time in June now!

 

I thought i made a post on this thread...........
Don't know what happened to it..........

Anyway...


Use a little penetrating oil on the band switch shaft a few drops at a time.
You should be able to loosen it up by ricking it back and forth a little to work in the penetrating oil.

I'll dig that transformer out tomorrow, post a picture of it and we can work out a deal.
In reality it is part of my stash of parts for a 4CX250 amplifier which I have a large number of the parts for now....
But I am open to letting it go for a reasonable price.