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SteppIR Tuning Relay is no longer in production.

N8LP SteppIR Tuning Relay

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N8LP SteppIR Tuning Relay

The SteppIR Tuning Relay was developed in response to a thread on the SteppIR reflector for a way to protect the antenna from damage during tuning with high power. FM recommends that you not exceed 200W when the antenna is tuning to prevent possible damage. The unit uses current-sensing to trip a relay when the SteppIR motors are running.

The unit is placed in the power lead between the SteppIR power supply and the SteppIR controller. The principle of operation is that the current being supplied from the SteppIR power supply to the SteppIR box is sampled by a very low value shunt resistor. The voltage across the shunt resistor is compared to a preset level, determined by the sensitivity control. The control is adjusted so that the relay is just disengaged when the SteppIR is resting and the motors are receiving only a holding current. When any motor starts drawing running current, the relay will trip and hold until all motors stop running, and the holding current returns. Normally, your rig grounds the PTT line to key your linear amplifier. The N8LP Tuning Relay box provides isolated relay contacts that are placed in series with the PTT line center conductor. The PTT line shield is looped through the box without connecting to anything in the box. When the relay opens, the PTT connection to ground is broken, preventing the amplifier from keying.

Here is an internal picture of an assembled kit.

For the PTT wiring I chose to use panel mounted connectors instead of PC mounted ones. This allows the user to choose the connectors he needs and wire them as needed. The NC contacts and supplied RCA connectors should work for most rig/amp combos. If necessary, when assembling the kit, the PTT jacks can be wired to the relay differently than this if you need something other than standard PTT wiring. This might be the case if you are running QSK, or wish to totally disable the rig from transmitting during tuning, as opposed to just disabling the amplifier.

For more detailed information, click on the link below to read the Operating and Assembly manual. It also provides assembly details. I recommend printing the manual to make assembly easier. Assembly of the kit requires a low-wattage soldering iron and the usual small hand tools. It should take 1-2 hours to assemble. The PCB is silk-screened so that it is easy to identify parts location. Sockets are supplied for the relay and IC.

Manual in pdf format

Manual in chm format

NOTE:There is a possible issue with using the tuning relay with some of the latest Icom radios because the STR floats the ground to the SteppIR controller slightly above ground to allow for current sampling through a low value shunt resistor (0.3 ohms). Apparently, the CI-V port on these radios doesn't like the floating ground. SteppIR warns about this in their latest manual, but I haven't heard from any users about it.

 Visit Product Review page for SteppIR Tuning Relay.


Here are some comments from the three beta testers of the prototype unit...

"Well, I've been using it all last night and some of the day today as I chase 3B9C DXPedition around the bands. It's worked flawlessly, real cool little box! Purposely moving the SteppIR while keying the amp at 1.5kw output causes the box to switch, as designed, and cut off PTT. If you're still keying and SteppIR stops, the PTT is switched on and out comes 1.5 kw agn! Neat.

Even when brute forced this thing reponds appropriately and the amp (Alpha 91B) responds in kind. You have a winner here.

Its bright red "TUNE" LED offers a much easier to recognize indicator of when the SteppIR stops. MUCHO easier to see than the asterisk in the SteppIR controller. U can see yours out of the corner of your eye, where you have to be looking directly at the asterisk. Neat!

Bob, K8IA

"The N8LP STR got a workout this weekend in the WPX contest.  I did mostly S&P. When S&P and running ASSISTED with the cluster, one can move around... fast. I at times would on purpose key while the SteppIR was tuning and the amp would not kick in till it was done tuning. So cool!

The STR box is small so fits well just about wherever you would want to put it. The neatest thing is the tuning BRIGHT RED light that comes on while the SteppIR box is tuning, very nice feature when you are in a hurry, it lets you know to hold on a second.

Many times over the weekend DX stations would reply "who is the India". With a weak station I'd be throwing out my call while SteppIR was tuning and then amp would kick in about the time I'd get to the India. I'd chuckle to myself, yea it works!

Jon NJ7I

"I have just finished installing the SteppIR Tuning Relay in my system with
the 4 Element SteppIR and TS-2000 with a MA1000 Metron 500W out Amp.

Results? Brain-dead easy - works a treat - and the red 'Tune' LED is MUCH easier to see than the little flashing asterisk on the SteppIR controller display.

It shuts off the PTT until the antenna comes to a stop - and then re-energizes
it. All-in-all, an excellent addition to the SteppIR family –"

John, VE3NFK

Here are several recent comments from the SteppIR reflector...

Allow me to put in another plug for the Tuning Relay... It went together easy as pie and worked first time. Larry has done a terrific job in design and
build. I highly recommend the Tuning Relay as a "must have" for anyone running high power.

73, Dick WC1M

Here's another plug for Larry's SteppIR tuning relay - if you're running an amplifier, it's a mandatory part of your shack. Works great, easy to
assemble, and it's definitely worth the investment to protect your SteppIR antenna.

73, Joe WDM

As a very satisfied and thankful user, this is close to a "must have" item if you're running over a couple of hundred watts into a SteppIR beam. Do check out Larry's site.

Tom K1TC



Ordering information for the various options of the box are listed below. Please read through all the options before ordering, especially if you are ordering from overseas. Assembled units are available for $30 more, but due to my limited time, delivery will be delayed compared to kits. email me for ordering info and estimated delivery date.

For those who wish to pay by credit card, I have provided a secure PayPal payment option. PayPal allows you to place a credit card order now without creating a PayPal account, so this is very easy to do. There will be an additional fee of 3.5 % for PayPal orders. If you wish to use this option, click on the "Add to Order" button below the product you wish to order, and you will be directed to a "Shopping Cart" secure page to finish the order and enter payment info.

All orders not paid for in USD will have to be made thru PayPal so that the exchange rate conversions can be processed by PayPal. There will be an additional charge of  2.5% for these orders to handle the extra PayPal fees for handling foreign currency. PayPal orders can be accepted in US dollars, Canadian dollars, Euros, Pounds Sterling or Yen. In rare cases, there may be extra shipping charges which will be determined after I ship the order. In such cases, the extra shipping charge can be sent to my PayPal account email address which I will supply.

US orders are shipped USPS Priority Mail, 2-3 days. Overseas orders are shipped USPS Air Mail, about 7 days. Air Mail is the easiest to deal with in terms of customs. VAT is the responsibility of the customer... the customs form will show the basic purchase price of the order in USD, excluding PayPal surcharges and shipping charges... ie., $75 USD.

Be sure to download and print the assembly manual if you haven't already!

Here is the pricing for U.S. customers who wish to order directly...

Complete kit, includes PCB, parts and case.
$75.00 + $5.50 S&H - MI residents include $4.83 sales tax

Send a check or money order payable to TelePost Inc. to the following address:

TelePost Inc.
49100 Pine Hill Dr.
Plymouth, MI 48170

Be sure to download and print the assembly manual if you haven't already!

Here is the pricing for U.S. customers who wish to order by PayPal...

Complete kit, includes PCB, parts and case.
$77.60 + $5.50 shipping 

>Please include your callsign in the comments box when ordering. It is easier for me to keep track of buyers by callsign.

Be sure to download and print the assembly manual if you haven't already!

For overseas customers, including Canada and Mexico...

Complete kit, includes PCB, parts and case.
$79.50 USD plus shipping.

Shipping options. Due to recent problems with overseas deliveries, we now offer only USPS Express Mail shipping, 5 days, insured, trackable online at

Canada, Mexico: $25USD

Asia: $27USD

FEDEX also available at higher cost.

Email us for payment options.

NOTICE: Customs documents require an accurate value, and usually copies of the invoice. Please don't ask me to falsify these documents!

Be sure to download and print the assembly manual if you haven't already!

Alternative wiring ideas.

Here are some ideas for wiring for the IC-PW1. The PW1 is unique in that it uses a multipin connector to connect to the rig, and this connector includes band-switching, ALC and PTT wires. If you use this cable, then the PTT line has to be opened up, either in the cable or at one end at the connector. Alternatively, you could build an external box with a pair of DIN connectors on it to loop the cable thru. If you don't care about band-switching info, then the PW1 can be hooked up like any amplifier using the SEND (PTT) and ALC connectors on the back.

The first option is to build an adapter to insert into the ACC cable at the amp. This description is provided by Joe, W4TV. He also describes a method of connecting to a Yaesu Quadra...

The DIN-7 (male) plug will fit into a DIN-8 socket ...
Purchase 7PDM (7 pin Male) and 8DFIL (8 pin Female)
connectors from BuxComm ( ... for $1.99
each. Connect pins 1, 2, 4, 5 and 7 pin for pin with
4 conductor shielded wire. Bring leads from pin 3 on
each connector to the STR.

This adapter will connect "in line" with the Icom ACC
cable between Icom transceivers and the PW-1 (can be
installed on either end).

A similar adapter can be made for the Yaesu Quadra.
It will be necessary to use the Quadra "Band Data 2"
(DB-15) connector since I have not been able to find
a female DIN-8/262 to match the Band Data 1 connector
(and Band Data connector on the Yaesu/Kenwood exciters).

For the Quadra, use a DB15F/DB15M. Connect all pins
EXCEPT Pin 2. Route wires from pin 2 of each connector
to the STR.

The Yaesu adapter will connect "in line" at the Quadra
end of the cable.


... Joe, W4TV

In addition, I think it would be even easier to build the adapter to pass all but the PTT signal through, and then use standard RCA cables from the rig to the STR, and from the STR to the amp, for PTT. Use the SEND1 connector on the amp for this.

Here is the second idea, which doesn't require any change to the rig, amp or cable, but does still require a little wiring..

Above are two possible circuits to try. They are the same except that one avoids the use of ground, which in the STR is not really ground due to the low side current sensing circuit. The idea is to reduce the drive from the exciter as opposed to opening the PTT line to the amplifier. I haven't tried this, so it is more a food for thought exercise than a blueprint for construction. Normally, the circuit is open, and therefore it has no effect. When the STR trips, the NO contacts close and a negative voltage is applied to the output jack through the two series resistors. R1 is used to set the allowable exciter output when the SteppIR Tuning Relay (STR) is tuning, and R2 is used to set a minimum series resistance. The voltage is applied to the existing ALC connection so that normal operation is not interrupted. I think it could be plugged into the ALC jack on either the rig or the amp, and will automatically be summed with any existing voltage the amp is sending through the ACC cable. I would start with about 10k for the pot and maybe 1-2.2k for the series resistor. This all depends on the ALC input Z of the rig and output Z of the amplifier... check the manuals before deciding on a value. The idea can be tested without the STR in the circuit to determine the correct values, of course. For a more permanent installation, a wall wart could replace the 9v battery.

The relay wiring in the STR is brought to several pads on the PCB, so it can be wired to the connectors any way you wish. You can start by using a single RCA connector on the backplane, but remember, the backplane is not grounded, so you would have to add a ground wire to the shell of the connector. Also remember that the "ground" in the STR is floating .3 ohms above actual ground. Alternatively (and probably better) is the circuit on the right, which would use a connector with isolated contacts so that the wiper and NO contact on the relay can be connected without relying on ground... or use just the center conductors of the two supplied RCA connectors.

I believe this idea might also be applied to any amp which runs QSK. It should reduce the drive from the exciter to a safe level, which not interferring with normal T/R switching.

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