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Jeez Louise...Harris quote for new IPA module for HT-20

Also, be careful with those IPA modules...I replaced a failing IPA with one of those Harris ones, and had to be very careful with reflected power. Those modules smoke really easily. Plus, they are heavy as hell.
 
The good ol' Harris Intercourse Typeration... predatory pricing lives! Continental also used the Blue Boxes as drive amps... call them and ask if they know someone who fixes them.
 
I nearly forgot -- in the earlier applications, Continental modified the MM&D boxes by removing the yellow wire up in the control section, thereby disabling the internal foldback becaus ethey controlled it externally. If you get a Blue Box which was in a Continental transmitter, pop the top and check that the yellow wire is connected.
 
littlejohn said:
The good ol' Harris Intercourse Typeration... predatory pricing lives! Continental also used the Blue Boxes as drive amps... call them and ask if they know someone who fixes them.
Click to expand...

Guess again... Continental is selling their own ripoff now - a brick made by Richardson instead of the Silicon Valley.

Big headache...
 
The first Continental IPAs were 'blue boxes' from MM&D. They put them in new production and in the original retrofit kits. They then went to a Silicon Valley box which was a bit more robust if someoone had ham hands setting it up. Current production fits two amps, the same ones as used in their later transistor FM radios. They all work well properly tuned. The later setups were and are easier to tune and less subject to failing the PAF test than the MM&D stuff when the reflected is a little high. Also, some of the early Telewave directional couplers used were less than accurate, which may have contributed to some of the blue box failures. For the IBOC low level combined radios, they have fitted a video amp to drive the grid for better linearity. They're doing 22KW in the three bay cabinet, and expect to do 27 - 28 with the outboard power vault. A tribute to the original 831-G1 design.
 
Glad we could help...

I don't even really work on Harris stuff anymore but I remembered the website when I looking for some other stuff...

The Harris 30 kW I used to work on I'm sure had one of these but I don't remember it ever blowing up on me :)

PS Anybody else ever changed a Mylar sheet? ;)
 
The Kapton sheet - screen bypass? Yeh, changed one years ago in a 25K. Bad radio. Got a ht-30 now which has a mickeymouse Delrin ring around the tube anode, glued to the Kapton with bathroom sealer. Great idea THAT was. I suspect the only reason they don't ground the screen and get more stability is, the Other Guys do it that way. The only positive point about the ht-30? It's the first Harris radio I've run in many years of doing this which will come on from cold and run reliably without fiddling. You can punch the plate on button and be reasonably well assured the thing will make RF. They persist in regulating the output by varing screen current though, which chases the tube up and down the load line as the current rarios change. Again, I suspect it's a case of "The Other Guys do it that way, so we will do it thisaway". If everyone from Quincy and Dallas would meet halfway, they could build a hell of a radio using all the good ideas of both.
 
Precisely...and watch for that feed thru insulator the couples B+ thru the rear
PA cavity wall...I have had them ARC on the inside and give you fits...looks like a short in the PA supply cabinet...but is simply an internal short to ground. Keep one of the nearby RF bypass capacitors (biscuit size) on hand...it will eventually die with a BANG!. Thanks JBI
 
Well, we finally got the new IPA module in yesterday.

If anyone needs one, please deal directly with Dennis Armstrong, he is listed under 'Contacts' at

http://www.svpa.com/gold.html

This module is a 'direct drop in', no monkey-motion required to make it work.

I found that 'IPA Reflected Power' is greatly influenced by PA tuning, and that anything over about 32 watts of IPA reflected causes an IPA VSWR Overload shutdown.

It took about 15 minutes of gradually sneaking up on full output, in this case 16 kW, into the dummy load.

Then took it onto antenna and re-tuned it.

Final readings were very close to original, except that by fine-tuning the PA input controls I managed to get full output at 2.41 amps PA instead of 2.45, an increase in PA Eff of 1.4 % over what had been running.

Thanks to all who offered suggestions and where-to-go-to-get-it advice.

Gary
 
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