Pressing a Harris Amp into Service

[ka1bwo]

Waiting for parts to build the control circuitry for one switch operation that will also attenuate the input drive via a current transformer and dummy load
Joe
https://www.youtube.com/watch?v=g4PmK01ZGSE

[flintstone mop]

I regret not buying one of those 7 yrs ago. Didn't take a lot of RF to drive them to beyond legal limit. Milliwatts!!!!
Very nice unit........I might still try to sneak a purchase under the "radar" one day, just to have one.

fred

[W2VW]

Remember WA1ABI?

He used a Harris amp (probably the HFL-1000) driven with a signal generator.

W2NBC had a sig gen on a few years ago.

Might work better than whatever else you want to use.

I recently heard one on the air that needed a lot of help so it IS possible to screw up.

Does that amp use a 3 phase blower like the AM-7224?

[AJ1G]

Remember WA1ABI?

He used a Harris amp (probably the HFL-1000) driven with a signal generator.

W2NBC had a sig gen on a few years ago.

Might work better than whatever else you want to use.
 

Modulation applied in the sign gen or on its output?

[W2VW]

Remember WA1ABI?

He used a Harris amp (probably the HFL-1000) driven with a signal generator.

W2NBC had a sig gen on a few years ago.

Might work better than whatever else you want to use.
 

Modulation applied in the sign gen or on its output?

To the generator.

[KA3EKH]

Cool, I have an option to pick up an AN/URT-23 transmitter that uses the same amplifier and power supply and also includes the T-827 exciter. I have an R-1051G receiver to pair with it and then will have the entire very large and heavy 1 kW SSB rig. Glad to see you video so now have an idea what noise the amplifier produces while in operation. The one I would be getting is signal phase.  Think I would like to set the whole mess up out in the shop but have to find the space for it keeping in mind that this will all eat up at least the floor space for a  six foot rack. Also would have to live with the noise while in operation.  Have thought about buying an S-250 Shelter on GLiquidators and building a system up inside that and put the entire mess on a truck and drive it around with running a couple remote pairs out for sending audio to and from the shelter so can stand outside and operate. Don’t think it would be good idea to operate it from inside the shelter. I know all this sounds crazy but that’s the kind of ways I have found to waste vast amounts of time and money. On the signal phase amplifier is it 120 or 240 volt feed? How much current is it drawing at full power? And how big is the power cable?
 

[n2bc]

The blower is not 3-phase, it is 120V 400Hz and spins at 11,000 RPM.  The 400Hz is provided by the RF-124 AC supply for the blower and ET meter.  There is also a 3-phase 400Hz supply that fits inside the RF-110 if you have 400Hz 3-phase available!  The RF-124 60Hz supply is 240V single phase 20A.

I drive mine through a 30dB 200W attenuator.  The exciter is always 'happy' looking at a 50 ohm resistive load.

The blower noise is not a big deal. A remote control box is simple to build and then move the screaming noise maker into the next room.

Here's a pic of the control box, and... something else



73, Bill   N2BC

[W2VW]

FB stuff.
Maybe the 7724 is same as yours. It sure sounds like it.
Have fun!

[ke7trp]

Cool.  That thing sounds like a shop vac running!   I am sure that can be dealt with. 

C

[Opcom]

Is it like a GRC-106 in the noise department? That one sounds more like a vacuum cleaner in a tornado.

I have not fired up the RF-110 here. The exciters and receiver are not yet repaired. time no time.. Mine has the single phase power supply unit with it.

[AJ1G]

Is it like a GRC-106 in the noise department? That one sounds more like a vacuum cleaner in a tornado.

T-195/GRC-19s put the 106s to shame in the blower noise department, especially ones with worn blower bearings.

[flintstone mop]

I need an RF 110 like a hole in the head, But the no-tune feature is nice.
I would hate to take a chance on a Fair Radio unit, as they are not going to be able to report on its condition. They will say that it is complete and it should work.
If the finals are dead, then there's more money flowing out the door.
I do see one at our expensive friends at Surplus Sales.....$3500 ea. NEW NO power supply
Fair radio is out of stock, but has a Navy version of the Harris for $1685 and P.S. for $165.
Kicking tires and hopefully not buying anything.......Gotta contain myself.

Fred

[ka1bwo]

Thanks for all the comments and questions which were already answered. I plan on locating the the amplifier on the other side of the wall next to entry door to the shack. The back pressure of the air inlet for the RF deck is 1 inch of H2O. A blower with about 200 CFM output could be a use to replace the high RPM fan if need for the high pitch noise reduction. I will have a range of input levels to deal with from the different exciters/modes to be used. My approach will be either a current transformer with multiple taps or continuous adjustable transformer to set the RF input level.     

[WA1GFZ]

How about a step attenuator?

[ka1bwo]

Hi Frank........The step attenuator would have to dissipate 50 to 75 watts average worse case (output ssb transceiver).

[WA1GFZ]

use a fixed pad (s) to get it down to the rating of a step attenuator.
Say 1/2 watt and get something that does 1dB steps.

[W3RSW]

Frank,
fire up your QS1E for minimum excitement. 

well, I'm still waiting; Phil says April.

[flintstone mop]

Is there any way to replace the noisy fan with something equivalent that would push the required air across the finals?

[WA1GFZ]

Rick,
HPSDR Hermes 1/2 watt XCVR soon.
I'm doing HPSDR Penny into a modified MRI amp. I'm up to 300 Watts PEP.
I just bought some 1200 watt MRI boards and in the process of moving one down from 80MHz. I have heat sinks and a big slab of copper 3/8 X 6 X 60 inch
that will be the heat spreader. I hope to do 4 boards into a combiner and run at reduced voltage. I have 1 board making good power on 75 but still need to modify more broadband transformers. 16 SD2932s should be enough.

[Opcom]

Is it like a GRC-106 in the noise department? That one sounds more like a vacuum cleaner in a tornado.

T-195/GRC-19s put the 106s to shame in the blower noise department, especially ones with worn blower bearings.

Before I sold my collection of them to an umm... Collector, I was considering putting a speed control on the external fan so that it would turn only as fast as necessary to keep internal temperature down. In indoor ham service only a little air is necessary especially on SSB and with the AM function being a 50-70W carrier and intermittent, there's no way that fan is needed all the time. That set, Like the RF-110 I suppose, was designed for 24x7 use under RTTY or other demanding conditions, and even more so since it is an outdoor unit.

It might be that the RF-110 could use a mod for less airflow when permissible, based on tube seal or anode temperatures. Measuring those temps could be challenging but IR thermometers are cheap.

In the GRC-106 a separate internal blower cooled the tubes and the rest of the 'sealed' set and the flow passed through an air to air heat exchanger about 18x12x2" in volume and therefore a simple thermistor and backup thermistor would be sufficient to measure circulating air temp or heat exchanger outer temp with (not sure about the T-195's arrangement)

The RF-110 is not sealed, complicating a solution. Maybe a remote high pressure blower. I don't want to put the pretty amplifier out of sight.

I need an RF 110 like a hole in the head, But the no-tune feature is nice.
I would hate to take a chance on a Fair Radio unit, as they are not going to be able to report on its condition. They will say that it is complete and it should work.
If the finals are dead, then there's more money flowing out the door.
I do see one at our expensive friends at Surplus Sales.....$3500 ea. NEW NO power supply
Fair radio is out of stock, but has a Navy version of the Harris for $1685 and P.S. for $165.
Kicking tires and hopefully not buying anything.......Gotta contain myself.

Fred

Doesn't the RF-110 have a knob on the front to manually select the band and then it will fine-tune itself? For that money a 208U-3, 208U-3A, or 208U-10 from Fair would be a better buy.

[n2bc]

The RF-110 has 19 bands, each is broad-band tuned, no 'fine tuning'.

I did a number of experiments with mine trying to reduce the noise.

First I made some baseline exhaust temperature readings @ 500W and 1000W over 10 minutes key down.

Then I disabled the internal fan and tried a few different squirrel cage blowers 'rigged' to the front panel of the RF-110. None were close to the internal fan - I figured that the internal fan being in place was likely a big impack on performance.  So, for the next round of testing I tore the RF-110 apart and removed the fan - not a fun job.

The next round of tests were much more successful. 

To make a long story a bit longer, I mounted a 250CFM blower on a panel below the RF-110 & fashioned a 4" x 4" horse-shoe shaped duct from the new blower up into the front of the RF-110.  Temp readings vs the original fan were excellent.  BUT, it was still too noisy to have in the shack!

Another point, the cooling inside the RF-110 is more than the 4CX1500s... there's a pair of 8122 drivers that take air and both the RF input and output transformer assemblies get some cooling air.

These things were clearly designed to sit in a room by themselves and operated remotely.

In the end, I tore off the horse-shoe duct and re-installed the 4" muffin fan screamer.  I suspect as I age past my current 64 years the 11,000 RPM while will become less and less of a problem!   

Here's a pix of the RF-110 with the added blower:

[Opcom]

Its amazing that the modded arrangement was still too noisy especially with the fan inside the rack but air is air.