Lowe HF150 keypad not working

[Steve G4WCS]

Picked up a tidy Lowe HF150. Its a superb little radio.
I've fitted a backlight using some leftover led strip lighting which makes the set look a lot nicer.
The only fault with it is that the keypad doesn't appear to work. There's 8 volts to the chip and the keypad bells out. I'm guessing the next step is a scope on the output to see if there are pulses present, but just wondering before I dig the scope out if anyone has experience with them, and whether it was a common fault ?

[SiriusHardware]

These units only have a 2-terminal plug, the data is superimposed on the supply voltage so you should see that the normally steady supply coming down the cable inner core flickers between two different voltages if you put a scope on it and press buttons.

The chip is actually one which was specifically made to go in remote controls. I have a homebrew version of one of these based on a PIC chip. It took me a while to get it to work because I did not realise the original R/C chip sends each 'packet' several times over for any one keypress, and the firmware in the HF150 actually looks for this repetition. My initial attempt only sent the data packet once and was ignored.

The most likely physical failure mode is failure of the cable where it exits the keypad or right next to the strain relief on the jack plug, but I assume you have already metered that out.

Edit: Just fired mine up again. As you type digits the number you are entering should build up on the display in right-entry mode like on a calculator. If you are entering fewer than 5 digits you may have to hit '#' to confirm. If you enter 5 digits then the frequency entered is selected on entry of the 5th digit.

[Steve G4WCS]

Thanks. Ive finally cleared the workbench so can lug the scope out. I was under the impression that I would have a bit more time to play when I retired but its proving not to be the case

[Steve G4WCS]

That was an easy enough fix. The keypad was pulsing ok but there was a dry joint where the signal travels from the main pcb to the control pcb . Its much more useful with a keypad.

[SiriusHardware]

An uncharacteristically bad bit of design, relying on a solder blob to make the connection between two PCBs at right angles. Any relative movement between the two boards was always going to crack that joint eventually. I think I would bridge that with a bit of wire.

[Jon_G4MDC]

Agreed. Adding a short wire U link will allow a bit of flex. Otherwise next time it will be trying to pull off PCB pads.

[jez_145]

Good work on the back light (and the keypad repair).

The HF-150 is a great radio. I've had mine since the early 90's and it's still going strong. I think I was about the only person to purchase the official Lowe back lighting kit for this, which was ridiculously expensive for what it was. Still, it makes the radio that bit easier to use in low light. I think I prefer your version though !

Jerry

[Steve G4WCS]

Noted on the wire links thanks. And for the backlight led technology has come on a lot since the radios are made. I used 2 small offcuts from some led striplighting I had over from the kitchen cabinets . Its bright and draws very little current, and can be retrounfitted if required

[SiriusHardware]

Years and years ago I built a single frequency (7.030MHz) CW transmitter which works well enough, but then I discovered those cheap Arduino-controllable frequency synthesis modules and I had the germ of an idea about slaving the frequency controllable transmitter and the HF150 together so that one digital frequency controller would make them tune up and down together over the CW portion of the 40m band.

I had the wherewithal to make it work in the technical sense, but what snookered it was the realisation that I was rubbish at Morse, despite having passed the 12WPM test some time in the mid nineties.

I do wonder if there are further commands which can be issued to the radio via its keypad input, such as tuning step size and step up / step down, mode select, memory channel select and so on. I've never owned a real HF150 keypad, only my homebrew one, so I don't have the specific manual for the keypad. Did Lowe ever make a CAT interface which was intended to be connected to the radio via the same input?

[Steve G4WCS]

Originally Posted by SiriusHardware

Years and years ago I built a single frequency (7.030MHz) CW transmitter which works well enough, but then I discovered those cheap Arduino-controllable frequency synthesis modules and I had the germ of an idea about slaving the frequency controllable transmitter and the HF150 together so that one digital frequency controller would make them tune up and down together over the CW portion of the 40m band.

I had the wherewithal to make it work in the technical sense, but what snookered it was the realisation that I was rubbish at Morse, despite having passed the 12WPM test some time in the mid nineties.

I do wonder if there are further commands which can be issued to the radio via its keypad input, such as tuning step size and step up / step down, mode select, memory channel select and so on. I've never owned a real HF150 keypad, only my homebrew one, so I don't have the specific manual for the keypad. Did Lowe ever make a CAT interface which was intended to be connected to the radio via the same input?

I’ve no doubt someone clever enough could/has backwards engineer the microcontroller inputs and make a computer interface, it does mention in the manual that the microcontroller sits there waiting for an input so its knows what its been told what to do. Its like any old commercial stuff though, unlike military, the design documentation has been lost long ago. Likewise on the morse, back in the 80’s I had been taught morse very well by an old G3 who took me under his wing, which enabled me to get my full licence, and after a night in the pub, used to enjoy a couple of hours on 80M CW after the lady next door had gone to bed and I wasn’t wiping out her Amstrad stereo. I do still have a tiny pic based trainer that I used to listen to at work, but am very rusty now

[SiriusHardware]

I wasn't considering writing alternative firmware for the onboard microcontroller (although I did once do that with a particular model of PMR radio). I was thinking more of exploiting the full command set already available through the keypad input, if such a thing exists.

Is there anything in the HF150 manual which explains what inputs are possible with the keypad? You can do frequency input with the numeric keys only and it seems to be frequency sensitive, so if you are already below 10.000MHz you only need to enter 4 digits, above that you enter 5 digits but on entry of the final digit the frequency changes to whatever you have entered. That leaves the # and * keys mysteriously unused.

...Or are they?

[SiriusHardware]

I've just done a search on 'HF150 on this 10 year old PC and it threw up a few interesting items. For example a brochure (attached #1) which mentions the existence of something called the IF-150, a computer control interface for the receiver.

[jez_145]

Originally Posted by SiriusHardware

I've just done a search on 'HF150 on this 10 year old PC and it threw up a few interesting items. For example a brochure (attached #1) which mentions the existence of something called the IF-150, a computer control interface for the receiver.

You just pipped me to it !

I've got an IF-150 and enclose a photo and the two manual pages for it which may provide a clue.

Cheers,

Jerry

[SiriusHardware]

I've also got the SMC version of the user manual - SMC took over the manufacture of the HF150 from Lowe for a time - and it explains more fully how to use the keypad. The manual file is too big to attach either as a .PDF or a .ZIP, so I have transcribed the bit about the keypad below. It will be interesting to see how much of this works for you Steve, it depends, I think, on whether your keypad is the original one based on the remote control IC or the V2 based on a microcontroller. I know for a fact that mine won't do the shift-number function for mode selection because it doesn't scan for more than one key held down.

Cut out and keep:

-------------8<----------------

KEYPAD ENTRY

If you plug in the optional remote keypad then you can tune the receiver by entering
frequencies directly. This is very useful for quickly checking stations at known
frequencies, or for setting the frequency in a particular band of interest and then
searching for signals with the main tuning knob. The keypad is separate from the
receiver so that it can be positioned alongside for convenient use. It is connected
by a short cable which should be plugged into the KEYPAD jack on the rear panel of
the HF-150. The keypad has 12 keys - the digits [0] to [9], the [#] key (enter) and
the[*] key (Cancel). As keys are pressed the digits are shown on the receiver's
frequency display.

Frequencies are entered in Kilohertz. The receiver will only tune to the entered
frequency when it is complete - either when sufficient digits have been keyed in
or when the enter key [#] is pressed. Frequencies above 3000KHz will enter
automatically as soon as the last digit is keyed. Those below 3000KHz should be
followed by the enter key [#].

For example

[1] [2] [0] [9] [5] tunes to 12.095MHz

[1] [9] [8] [#] tunes to 198KHz

Supplement to 'Keypad Frequency Entry'

The keypad is now being replaced with a re-designed internal configuration which
employs a small micro controller to decode the keys and output the data. While
the physical layout of the popular keypad has been retained a few extra features
have been included which still allows the keypad to be used with previous Lowe
receivers i.e. HF125/HF225.

The frequency entry remains unchanged, with frequencies of 3000KHz and above
being automatically selected as the last digit is entered on the keypad.
Frequencies of 2999KHz and below are selected with the [#] key as the last
digit.

HF-150 users may also access the different modes in any order by holding down
the '*' key and then using any of the numbers 1-8 as indicated by the keypad
diagram below.

Keypad V2 layout showing mode selection via keypad.

[LSB] [USB] [AMn]

[ASL] [ASU] [AM]

[ASD] [ASF]

[*] <------ Shift Function

Because frequencies entered by the keypad are to the nearest kilohertz, it
may be necessary to retune the receiver slightly to correctly resolve single
sideband signals or when using the receiver in AMS mode.

If you press an incorrect key on the keypad, the current digits can be cleared
by pressing the cancel key[*], after which the frequency should be re-entered.
Please note that once keypad frequency entry is started the other controls
on the receiver will be inoperative until entry is completed or cancelled.

There is quick access to frequencies stored in the receiver's memories. If a
number between 1 and 60 is keyed in, followed by the enter key [#] then the
appropriate memory is recalled and the receiver's mode and frequency set. To
key in a frequency below 60KHz, prefix the number with a zero.

For example

[2] [#] recalls memory 2

[4] [5] [#] recalls memory 45

[0] [4] [5] [#] tunes to frequency 45 KHz

[SiriusHardware]

jez145, that looks like great info. Unfortunately what that does not tell us is what numbers the IF-150 sends to the radio when you send those psuedo-english commands to the IF-150 from a terminal. But it gives us an idea of the full command set available through the keypad interface. I notice that even the proper Lowe interface is transmit-only because the keypad interface is a receive-only input. Any characters sent back to the user by the IF-150 are generated within that unit, not sent by the radio.

[SiriusHardware]

The thing I particularly notice is that the IF-150 seems to be able to send frequencies with greater precision than the 1KHz steps allowed for the keypad - so there must be a command set that it can send that the HF-150 understands, but the keypad is not designed to send it.

[jez_145]

Originally Posted by SiriusHardware

.... Unfortunately what that does not tell us is what numbers the IF-150 sends to the radio when you send those psuedo-english commands to the IF-150 from a terminal. But it gives us an idea of the full command set available through the keypad interface.

Yes, I suspect that the IF-150 doesn't actually send the frequency as it is entered but as a number of 8Hz steps, possibly including an offset. Since the receiver has a tuning range of 30 kHz-30 MHz, this could possibly take the form of a number ranging from, say, 0 to 3750000, so 3750 could represent 30kHz, 24750 might represent 198kHz and 3750000 may represent 30mHz for instance. Looking inside the IF-150 (attached), you can see that the circuitry is rather more advanced than the basic keypad and includes a micro that could easily handle the data entry, conversion and validation. In any case, the output is very different compared to that from the keypad unit.

A quick look on the scope reveals that most, integer, frequency commands seem to output six packets of "bits", regardless of the frequency. However, when a decimal point is included in the data, as in the 28734.324 example, an extra couple of packets are added. The MOD commands just seems to output a single packet to represent the chosen reception mode. It looks very similar to typical output from an infra red remote control - probably using Manchester encoding etc. Sadly, I haven't really got the time or inclination to study this in depth but it's certainly "crackable" with a bit of effort. Either that or find John Thorp and see if he remembers how he did it !

Jerry

[SiriusHardware]

I wonder if the code in that 87C751 microcontroller is protected? Sometimes people did forget.

As I mentioned my own HF150 keypad is a homebrew effort based around a PIC16F690 - I made it based on the information about the keypad signalling in the service manual, and it appears that the original keypad chip sent 5-bit packets, but what tripped me up originally was that the keypad chip always sends several repeated characters for one button press and the HF150 actually expects that and looks for several repeated characters before it will respond. I was originally sending perfectly formed 5-bit single characters and the HF150 just sat there like a stone. It wasn't until I started sending three identical characters one after the other that the unit started to respond.

So my first question about those packets you are seeing would be, how many of the characters in the packets are repeats?

[jez_145]

Originally Posted by SiriusHardware

... So my first question about those packets you are seeing would be, how many of the characters in the packets are repeats?

Well, in the case of the IF-150, apparently none !

I've attached a couple of zip files containing scope screenshots of my findings. The first shows the output from my legit Lowe keypad, which does repeat each digit entered as you mentioned - seven times no less! In contrast, the second file provides some IF-150 output for frequency, mode and memory selection. As you will see, this appears to use a bit of a different approach compared with the keypad.

Jerry

[Steve G4WCS]

Glad my post has stimulated some interest in these great little radios