Can the 6400M radio be used with a Heathkit SB200 Linear Amplifier?

Rapidrob

We just got the 6400M. I have a working Heathkit SB200 linear amplifier ( tube type amp ) which has been upgraded and working very well with my ICOM 756PRO II radio with no issues via an Ameritron ARB704 interface device taking care of the PTT signal,etc.
Can the 6400M be used using the ARB704 to the SB200 in a normal manner?
I'd hate to damage the new radios computer or the like due to an incompatibility issue.

Ha Gei

I see no reason why that should not work . The relay output is isolated anyway.

The only issue i see...which we had with tube amps:

The 6400 is very picky on SWR and lowers power very soon . So, if the input circuitry of the SB200 does not provide good SWR, you may need to use the tuner of the Flex every now and then . We got fed up with that habit quite soon and went to a solid state amp .

Harry

Gord-VA7GP

@Rapidrob your ARB-704 is the perfect interface between your Flex and your Heath amp. I use an ARB-704 (with Collins 30S-1) and my Flex is completely happy. In my particular case, my 30S-1 amp only has +12V on the T/R jack, but the current exceeds the Flex' capabilities, and the inductive kickback-on-release would toast my Flex.

I use my amp with other gear (Kenwood TS-850S/AT) that provides a fast +12V output for TX. I built an opto-isolated / open-collector interface for my '850 to the 30S-1, and am happily able to parallel both my own interface and the ARB-704.

In Summary: I've found the ARB-704 works well with the Flex. Being all-solid-state, your TX - RX delay will be dominated by relays.

Rapidrob

Thank you for the replies. What would be the correct wiring to the Flex - Ameritron 704 -and out to the Heathkit?
Here are the wiring photos from the ICOM 756PRO II ( one wire only ) to the 704 and then the Heathkit.
The orange Motorola cable comes out of the ICOM to the 704
https://i.imgur.com/N8DT5t6.jpg
A black cable comes out of the 704 to the Heatkit Antenna Relay port.
https://i.imgur.com/M2MLunT.jpg
https://i.imgur.com/2wJnl31.jpg
What is the correct wiring run for the Flex to the 704 and then to the Heathkit? is ALC used?
***********
The Heathkit's SWR is very stable and my test equipment shows 1: 1.2 to 3 max at 900 Watts out on the ICOM set to 100 Watts out.
The FLEX to amplifier instructions are vague as to going to an electronic relay interface.
Thank you for any helpful instructions. We really looking forward to reaching out and making some DX contacts with the new radio.

Gord-VA7GP

The ARB-704 requires +12V power in order to operate. So, you need to provide that.

Then, it requires a TX input (from your Flex). I used a long RCA-to-RCA cable for this.

Lastly, it requires an amp-TX output cable to your SB-220. In my case with my amp, I used another long RCA-to-RCA cable.

That's it - 3 connections are required.

Now, about ALC. The ARB-704 simply passes the ALC through, from the RCA-jack to the multi-pin rig-specific jack. If you want to use ALC, and especially if you're not using the mutli-pin rig-specific cable, then just run ALC from your SB-220 to the Flex. Nominally, ALC runs around -5V or so... However, in my case i have plenty of amp-headroom, and do not experience splatter (use websdr site to listen to yourself, or use a meter, etc). ALC is there to prevent over-driving into non-linear region, and you can be just as clean if you stay light on the gas-pedal. Don't overdrive. Googling should show you extensive arguments over a very long time if you want to dive into the pros and cons of ALC... 😯

Rapidrob

So, if I understand your reply.... My 704 is powered by a 12 VDC supply.
I only need ONE cable FROM the Flex radio to the 704, which in turn, has a 2nd cable that goes to the Heathkit amp.
Which Flex radio port should I use?

Rapidrob

Reading the online manual, it looks that the Motorola jacks I need to use are TX1-3 only,is that correct?

TX Request says it stops the signal going to the amp.

Rapidrob

I did a truth table using a DVM and figured out which Motorola jack to use. I'm using TX1 now with a "ground" signal from the radio ad it is working as it should.

Rapidrob

We made a bunch of contacts last night using the Heathkit SB200 at 900 Watts. Every thing worked as it should with great signal and audio reports.

Still lots to learn with this new radio.