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[KI4UIA]

i have a ameritron als-1306 amp driving it with a yaesu ft-991a and using a mfj-998 tuner. using a dummy load it works fine but when putting it on a antenna (hy gain av-6160, mfj-1982 or a folded diode pole) the swr jumps to 1.4 and amp goes into by pass. i would appreciate any and all sugesstions as to what could be wrong.

[K4PIH]

Nothing wrong, it's the design of the amplifier. I have an Ameritron 1306 into a TTFD, driven by a Codan Envoy. I've run into a very similar problem between 1.4 and higher SWR. How much are you driving the amp with?
I only drive with 30 watts or less and get 5 - 600 out of the amplifier. Any more drive and the amp goes into standby. The amp is also very sensitive at the outer fringes
of the frequencies it's designed for. Into the dummy load presents an almost perfect match. Using your antenna is the "real world". Either your antenna has problems, or is causing
a RF loopback into the amplifier.

Things to check:

Your antenna, coax, and connections all good? No shorts or water in the connections?
Lower your drive on the Yaesu and see if that makes a difference.
Why are you using a tuner?

These are good amplifiers and sensitive to higher SWR so that the finals don't get destroyed. 

[KH6AQ]

TCVR -->AMP --> ATU --> AV-6160 or MFJ-1982 or Dipole

I would focus on the MFJ-998 ATU. I have an MFJ-993BRT and used to use an MFJ-994B with an AL-600 amp. The ATUs sometimes retune when RF power is increased and during this tuning process the SWR at the amp can momentarily jump quite high. The ALS-1306 manual says (page 5) "The amplifier will shut off if an incorrect band is selected, if antenna SWR is too high (even for an instant),..."


A work around I have used is:

Tune the antenna at 10W straight from the transceiver
Increase to 100W and ATU may make adjustments
Activate the amp and slowly increase RF power to the amp's limit

If your antennas present an SWR within the acceptable range for the ALS-1306 you can remove the ATU.

[KD6VXI]

These are good amplifiers and sensitive to higher SWR so that the finals don't get destroyed.

That is SERIOUSLY debatable.  Look at the archives.  A LOT of users have problems with them, multiple trips back, etc.  They do not have a good reputation.  W8JI has found that the heat sinks are not even, causing thermal failures of the power transistors, among other defects introduced after the design phase (read this as MJF / Ameritron cheaping out).l

As to the protection circuits.  They don't care about SWR.  They care about reflected power.

[AC2RY]

TCVR -->AMP --> ATU --> AV-6160 or MFJ-1982 or Dipole

I would focus on the MFJ-998 ATU. I have an MFJ-993BRT and used to use an MFJ-994B with an AL-600 amp. The ATUs sometimes retune when RF power is increased and during this tuning process the SWR at the amp can momentarily jump quite high. The ALS-1306 manual says (page 5) "The amplifier will shut off if an incorrect band is selected, if antenna SWR is too high (even for an instant),..."

A work around I have used is:

Tune the antenna at 10W straight from the transceiver
Increase to 100W and ATU may make adjustments
Activate the amp and slowly increase RF power to the amp's limit

If your antennas present an SWR within the acceptable range for the ALS-1306 you can remove the ATU.

When you use amplifier, you have to use tuner that does NOT try to re-adjust on its own. Then proper way to integrate tuner into the chain is to use one that can talk to radio external tuner interface. Also amplifier needs to be in bypass while tuner is adjusting. I do not not know if MFJ-998 can be locked to prevent auto-adjustment while amplifier is not in bypass. If it cannot, then you need a different tuner.

[KH6AQ]

AC2RY, good points and if it is the tuner that should fix the issue.

The MFJ-998 can be set to not tune on its own. To do this it can be placed in semi-automatic mode per manual page 8.

The tuning/operation procedure with the ALS-1306 them becomes:

Switch the amp to standby
Apply 10W and press the MFJ-998 TUNE button
Dial the transceiver to the drive power the amp requires
Switch the amp to operate

[KI4UIA]

thanks exeryone for information i have use a mfj-986 and a mj-989d to no relief. i have put power into amp to 15 watt but i have not tried putting the tuner int semiautomatic. so i will try that. again thanks to everyone.

[K4PIH]

TCVR -->AMP --> ATU --> AV-6160 or MFJ-1982 or Dipole

I would focus on the MFJ-998 ATU. I have an MFJ-993BRT and used to use an MFJ-994B with an AL-600 amp. The ATUs sometimes retune when RF power is increased and during this tuning process the SWR at the amp can momentarily jump quite high. The ALS-1306 manual says (page 5) "The amplifier will shut off if an incorrect band is selected, if antenna SWR is too high (even for an instant),..."

A work around I have used is:

Tune the antenna at 10W straight from the transceiver
Increase to 100W and ATU may make adjustments
Activate the amp and slowly increase RF power to the amp's limit

If your antennas present an SWR within the acceptable range for the ALS-1306 you can remove the ATU.

When you use amplifier, you have to use tuner that does NOT try to re-adjust on its own. Then proper way to integrate tuner into the chain is to use one that can talk to radio external tuner interface. Also amplifier needs to be in bypass while tuner is adjusting. I do not not know if MFJ-998 can be locked to prevent auto-adjustment while amplifier is not in bypass. If it cannot, then you need a different tuner.

Never had issues with the four ALS1306's I have. In my application I don't use a tuner, no need.

[VE7RF]

TCVR -->AMP --> ATU --> AV-6160 or MFJ-1982 or Dipole

I would focus on the MFJ-998 ATU. I have an MFJ-993BRT and used to use an MFJ-994B with an AL-600 amp. The ATUs sometimes retune when RF power is increased and during this tuning process the SWR at the amp can momentarily jump quite high. The ALS-1306 manual says (page 5) "The amplifier will shut off if an incorrect band is selected, if antenna SWR is too high (even for an instant),..."

A work around I have used is:

Tune the antenna at 10W straight from the transceiver
Increase to 100W and ATU may make adjustments
Activate the amp and slowly increase RF power to the amp's limit

If your antennas present an SWR within the acceptable range for the ALS-1306 you can remove the ATU.

When you use amplifier, you have to use tuner that does NOT try to re-adjust on its own. Then proper way to integrate tuner into the chain is to use one that can talk to radio external tuner interface. Also amplifier needs to be in bypass while tuner is adjusting. I do not not know if MFJ-998 can be locked to prevent auto-adjustment while amplifier is not in bypass. If it cannot, then you need a different tuner.

Never had issues with the four ALS1306's I have. In my application I don't use a tuner, no need.

Are they reliable on 6M ?   Can you operate them at say 500-700 watts on EME data modes on 6M.... like 1 min on...and 1 min off ??    Tnx.

[KD6VXI]

You already know the answer to that, Jim.

Still have not heard back from 'JI on your question.


--Shane
WP2ASS / ex KD6VXI

[VE7RF]

You already know the answer to that, Jim.

Still have not heard back from 'JI on your question.


--Shane
WP2ASS / ex KD6VXI

Dunno abt the 1306.   Some are built right and run pretty good.  I did notice that they are essentially 2 x ALS-606's in one box...but with a slight twist.  Each 606 does NOT have a LP fiter. Instead they combine em..then run the output through a single set of LP filters. The LP filters look pretty robust to me.   Red cores used on 160+80m + 40m.   Yellow core on 20m.  Air cores on 15-10-6 m.   The wire ga on the 6m air core is pretty substantial.

Lemme know if u hear back from JI.  That's much appreciated.