Interfacing with the Heathkit SB-230 and ANAN 7000 DLEMKII

[KC4LZN]

I recently acquired a Heathkit SB-230 and the previous owner used it with an Icom IC-7300. Worked wonderfully.

Educate me where I'm possibly missing a step.

I have Ant1 going to the input of the amp. Output to an SWR meter and then into a dummy load (until I can assure myself this is working).

I have an RCA cable going from PTT Out to the jack on the back of the amplifier. ALC is not connected.

Drive set to 10, when I transmit, I'm not hearing the relay kick in on the amplifier.

Is there a setting in the software that needs to be checked to engage the PTT Out?

John

[w-u-2-o]

I don't have an SB-230 so I'm not 100% sure of my interpretation, but...

You may have damaged your 7000 by directly connecting the PTT output to the PTT input of the amp. It is probably not capable of keying that amp directly.

The SB-230 is a typical amplifier design of that era. Such amp's used a -120V power circuit to one end of an internal relay coil. The PTT input of the amp provided a means to connect the other end of that coil to ground. You can see this on the SB-230 schematic:

https://televideo.ws/images/docs/SB-230/sb230schem.pdf

As you can see from the schematic, the amp PTT input is connected via SW-2F to both relay RY2 and the base of Q1. When that input is grounded it causes Q1 to conduct after some period of time thereby actuating time delay relay RY2 and allowing the -120V to flow through the coil of RY1 and out the PTT port to ground.

If so, then at a minimum you may have replace the PTT output MOSFET on the Orion board. Once that is done, then you'll have to obtain or build a solid-state to relay PTT adapter.

You can test that the amp works by simply shorting across the terminals of the PTT input.

You can test that the ANAN works by using an Ohmeter with the positive lead on the PTT center pin and the negative lead on the ground. If it shows near 0 Ohms with PTT out active the output MOSFET is probably OK.

The PTT output MOSFET on the board is an IRLR120NTRPBF. It is rated for a maximum drain to source voltage of 100V and a maximum current of 10A.

[KC4LZN]

First, to answer your tests in regards to the relay on the amp and two the PTT on the radio.

No, the radio is not damaged. in receive, the PTT out reads infinity and when keyed, reads 11 ohms. Not sure what the parameter is for this but it does not read zero. 

The amp relay closes when shorted across the PTT input terminal. 

I successfully completed a CW and digital QSO after the fact and into a dummy load, it transmits 100 watts on dead key CW. 

One thing I failed to mention about this amplifier. This amplifier is not in its original build and I was not the one who built it. I bought it from a fellow ham who bought it from a ham and I was informed that it was modified to use the GI-46B tube because of the unavailability of the original tubes. 

Because it was used in conjunction with an IC-7300, I saw no problem with using the 7000. I have not tested again with the 7000 and do have an IC-7300 as the previous owner had and will test with it later (maybe) and later may be after Christmas . 

I will definitely re-think any use of this amp with this rig, and even potentially not even using it with the 7300. While I have experienced trial and error, this isn't one of those moments for me to be without one, less two radios.

I do not know what the reading was prior to this test. I do not use the PTT out on this radio so I am not sure if it was working properly or not. I also understand, 11 ohms is not any where near zero. Is that within parameters for the MOSFET to function properly or do you think it is in need of replacing?

John

[w-u-2-o]

Not sure, John. I could measure mine but I won't have an opportunity to do that until later in the week.

Perhaps someone else could make that measurement?

If the amp was being used with a 7300 then it might have an internal mod to make it more compatible with the solid state, low current, low voltage PTT outputs used on modern gear. Any chance you could take a peek inside it?

[KC4LZN]

Absolutely. With the holidays approaching, gonna be tricky but I'll get under the hood, time permitting and answer here.

73
John

[WM4CH]

I have an SB-220 that supposedly has the keying mod to make it compatible with DC keying transitor transceivers. I use it with an IC-7300 but use an MFJ keying buffer because although this amp supposedly has the mod, I don't know what the mod is capable of sinking. There is no real standard and no way to know when the mod was made and to what standard it was made to, and I was too lazy to look at the circuit built into the amp and figure it out, so I use the buffer.

[KC4LZN]

I'm learning more and more about this amp.

Yes, it was modified and this is what I have.

It is a Russian GU-34 amplifier built into a Heath SB-230 case using the same power transformer and RF deck that the SB-230 used. It has GI-46 tube installed.

If I need to get the interface relay for this, I will. Definitely don't want to fry anything.

John

[w-u-2-o]

https://mfjenterprises.com/products/arb-704#description

[KC4LZN]

Thanks, Scott.

I should have it in a day or two.

I'm still concerned about the 11 ohms. For any continuity measurement, that, to me would be out of spec. I'd expect less than .5, no more than 1 ohm.

John

[w-u-2-o]

Unfortunately I will not be home enough until later this week to measure anything. Maybe Glenn would consider making the measurement?

[DL2XY]

Looks reasonable, mine is 5.6 Ohm.

[KC4LZN]

Looks reasonable, mine is 5.6 Ohm.

Thanks for the check.

I'll be getting the interface buffer in a day or two. Hopefully this'll be the ticket.

73
John

[KC4LZN]

Received the Ameritron 704 today.

Whew!

Works like a charm. I am a happy ham now. Can't wait to fire up some serious power now with the key. Huge lesson learned and avoided a major disaster.

To all, Thanks for the inputs.

73
John

[w-u-2-o]

Great news!

[KC4LZN]

One other question.

In transmit, where is the setting for TX or PTT delay? I saw for CW the transmit delay was set to 300 ms.

In some reading, I'm finding recommendations for anywhere from 15 to 30 ms for TX Delay.

Is there a separate tab for the actual PTT delay time?

73

John

[w-u-2-o]

Setup > General > Options > Options-1

[KC4LZN]

Thank you, Scott.

[w-u-2-o]

Make sure you read the tool-tips pop-ups carefully. Those settings can be a bit confusing.

See also this topic: viewtopic.php?f=9&t=4382