Batboard

Just purchased a two channel low split Maxtrac. From 29.6 and up the power out is 40 watts which is where I set it. If I try putting in a freq. between 29.5 and 29.58 the power out jumps up to eighty watts. Tried different power settings in the software but cannot bring it down on those lower channels.
Anyone have any ideas?

Thanks

You will have to put in a manual power control.
The alignment does nothing below 29.6 so it runs wide open.
You will find the deviation may be off too.

Too bad they couldn't have made it 29.5 instead of 29.6!!!

Still awaiting a smart computer guy to hack the tuning ranges for all Maxtracs....

I have one I will be adding manual power and dev controls to.

Thanks Max-trac. Spent the last hour looking at that on repeaterbuilder.
Looks easy enough, will pick up the multi-turn tomorrow.
Yep, 100kc more would do the trick!

The reason your power is going through the roof is because the logic board's programming has range-specific settings tied to whatever split the radio was initialized for. Exceeding that initial range goes outside the lookup table, and causes the power to go full-bore.

A more elegant solution than the multiturn pot trick is to simply blank the board, and reinitialize it in the bandsplit you desire. Once you go through the subsequent alignment, power control will behave normally.

Keep the peace(es).

Opened the radio up to do the manual power control mod and found out I have the HLN5172A 5 pin logic board. Does anyone have the info on where to cut the board trace on this one? It has the V5.34 chip so it will be a keeper if I can get this mod finished.

On that board the two resistors are on the bottom side of the board, underneath the D/A chip. If you find where the chips pins come through the board you should see 5 resistors between them, one by itself and 2 pairs of 2. The 56K resistors mentioned in the articles are the pair towards the back of the radio. Remove those and connect your circuit to the pad that connected them together. I saw in the one article how they said to cut the pad to avoid losing the resistors, but if you wanted to undo the mod I'd rather get a couple of new resistors than have to repair a hacked up trace. The 9.6V connection should remain the same, pin 1 of the cable going to the PA.

The blanking trick doesn't work on the lowband High or Lowsplit.
There is no split below 29.7 nor above 50.

I have done it on the VHF to get one to tune properly below 145. However either the xtal or tuning data was different as it was out of range (ie the different splits have different tuning values).

Thanks a bunch guys, will flip the board over and take a look.

Steve

I've done several in the low split, 29 to 29.7, and in the high split,50.3 to 54 Mhz, maxtracs and radius by the blanking/reinit method and never had the run away power problems. Even 2 radius that I re-blanked as 32 channel maxtracs behave perfectly at 60 watts from 29 to well over 32 Mhz and the other from 50.3 to 54 MHz at 60 watts across the band.