AMP Relay (Y301) PN

[AC1I]

I am seeing an issue where my HR-500 occasionally does not seem to release a relay when the PTT signal is de-asserted. When this happens the next assertion of the PTT results in no amplification (indicator set), but the drive power is passed through. Asserting and de-asserting the PTT clears the issue. I suspect that Y301 (AMP_RLY) is the problem, but I can't read the Part number.

Would someone please provide me with the Part number for this relay?

Thank you

Patrick AC1I

[jcve...@gmail.com]

Hi Patrick,

Here is the ordering info for the relay:

RELAY GEN PURPOSE SPDT 16A 12V, TE CONN, RZ03-1C4-D012, MOUSER, $1.46

73,

Jim WA2EUJ

[AC1I]

Thanks;

 But, I'm confused; The schematic (HR500 LP FILTER SCHEMATIC REV D) indicates that Y301 is DPDT. Am I missing something?

Patrick AC1I

[jcve...@gmail.com]

Yep, you are right, I had the wrong relay. This is the correct unit:

RELAY DPDT 12V, KEMET, EA2-12NJ, MOUSER, 551-EA2-12NJ

[AC1I]

I finally got around to replacing the relay (Y301), that was not the problem.

Here is the issue; randomly, I have a condition where when the PTT is asserted there is no amplification. What I see/hear is:

1. Assert PTT, indicator changes from green to red, you can hear the relays (Y101, Y102, Y301) engage. (Well, maybe I only hear Y101 and Y102)
2. Transmit, have amplification.
3. De-assert PTT, indicator changes from red to green, but, you do not hear the relays disengage.
4. Assert PTT,  indicator changes from green to red, you can hear the relays (Y101, Y102, Y103) engage.
5. Transmit, no amplification
6. De-assert PTT, indicator changes from red to green, but, you do not hear the relays disengage.
7. Condition remains
8. Click the PTT on/off a few times until you hear the relays disengage.
9. All works well, until next time.

Instincts say to replace Y101 and Y102, but and ideas would be appreciated. I don't have extender cable to separate the rear panel PCB and it is not that easy to get to the back of the board to troubleshoot.

Condition is very random, and I can operate for some time before it occurs, but when it does occur it stays that way until I bounce the PTT input several times. What I truly find odd is that I always hear the relays engage, even after I don't hear them disengage.

Thanks

Patrick AC1I

On Sunday, June 2, 2024 at 9:37:09 AM UTC-4 jcve...@gmail.com wrote:

[AC1I]

I can't say that I understand it, but there seems to be a condition where the HR-500 sees the PTT assertion well enough to activate the indicator/bypass, but not well enough to activate the amplifier. I was triggering the PTT with an open-collector output, but apparently I was just on the edge of some detection threshold. I have studied the schematics, but frankly I just don't see it. Anyway, I swapped the OC output for a direct connection to my IC-705 (via relay) and everything seems fine now.

Confused, but operating;

Patrick AC1I

[KD8K]

I have seen something similar on my HR500, especially on CW. PTT would trigger, but no amplification, causing random CW elements to not be amplified. 

Appears like some type of timing issue with PTT. It was random but would happen at least a few times during a CW QSO. I do use Semi-QSK, with the CW delay set to around 500ms

John KD8K

[jcve...@gmail.com]

HI John,

I have also seen some infrequent, random behavior with the PTT. It's an interrupt service routine that is called when a change is detected on the PTT  line. It doesn't happen reliably enough for me to definitively troubleshoot it so I put bandaids on what I think it might be. If we can find a repeatable condition I might be able to debug it.

73,

Jim WA2EUJ

[AC1I]

It depends on how random you are willing to work with. I was seeing this at about 1 in 20 attempts. Once it occurred it was persistent unless I switched the PTT on/off at a rate of around 5 cycles per seconds. It is possible that there was some hysteresis on the PTT line from the 74HCxx chip (but it did have decoupling caps), I never checked with a scope. I can only speculate, I would suspect the PTT off transition is the culprit. I have not seen it at all since I started driving it directly from the radio.

Patrick AC1I

[Geert Jan PE1HZG]

Hi all,

I have also encountered this a few times, and I now wonder if there is a timing issue in the firmware. Since I "made my own changes" I did not complain here as I thought it was my own bug but perhaps not.

I have seen the issue mostly when not operating the KX3 microphone correctly, causing a few switches back-and-forth. And since it didn't replicate...

What would be helpful is "how to recreate"

If you have a way to trigger this, I'd be most interested.

73, Geert Jan

(pe1hzg at arrl dot net)

PS: a number of people have contacted me, over time, about "firmware changes" in past months. Due to personal circumstances I have not been able to keep up (sorry!). Today someone "new" contacted me and it is time for me to catch up, clean up and connect everybody, since, for some, Google groups gave challenges (I'm struggling a bit, too!). And, given that the HR500 kit is no longer sold, we need to ponder how to do firmware since some of the upgrades I have seen are significantly better than mine. I hope to be able to catch up this week.
@Jim, how do you see the future of firmware changes, given the status of the HR500? For "only a few kits sold", I see a lot of activity...

[Andrew Catanzaro]

Phil Salas AD5X presents a construction article in September QST for a QSK adapter for *any* power amplifier.  The PTT on the amp is keyed on continuously and his device uses a new Panasonic high speed, high power relay that will handle the full legal limit.  It keys the transceiver around the amp during receive and into the amp on transmit.  He compares the $8 relay's attributes favorably with a Jennings vacuum variable.    

This device would not only allow one to run QSK (or semi-QSK) CW, it would totally circumvent all the T-R and PTT issues in this thread.  He offers a complete Mouser bill of materials in the article.  If you contact him directly he is selling the PCBs for a small price.  I plan to build two.  First is for the HardRock to get around the sometimes-it-doesn't-send-all-the-dits problem and the other for my Expert SPE 2K amp that doesn't do QSK.  

73 - Andy W9NJY

[jcve...@gmail.com]

OK so before anyone tries Phil's circuit with a Hardrock-500. Remember that a pair of VRF2933 MOSFETs is currently $330.

1. Leaving the amp biased all the time is VERY risky. The control circuitry in the HR500 won't apply the bias until all of the switching has settled down and removes the bias then the amp is unkeyed or a fault occurs BEFORE any relays are switched. Switching relays with the amp biased on could easily lead to the amp putting power into an open circuit destroying the MOSFETs in a brief blue flash (BBF).

2. Fault conditions in the Hardrock-500 are cleared by un-keying then re-keying the amp. If you just strap it in TX and a fault occurs, you can't clear it.

3. The frequency counter that prevents a band mis-match from destroying the MOSFETs only operates on the first burst of RF after the amp is keyed so if the amp is keyed all the time and you change bands on the radio and forget to change the band on the amp expect a BBF

4. The relay he selected is only appropriate for full-legal power at 50 ohms. If your HR500 has the tuner and the antenna impedance is very low the 8 amp rating of the Panasonic relay is not sufficient. The relays in the HR500's ATU are rated at 16A. If that relays fails you'll get a BBF. The 2 kV caps are probably OK for most loads, the HR500 has 4 kV caps in the ATU.

5. He mentions in the article that you have to worry about isolation because the amp is always active and could easily turn into an oscillator and destroy the MOSFETs. He's using 100W in amps which have 15 dB or less. The HR500 has over 20 dB gain so this is even more critical. If the HR500 goes into oscillation; BBF.

6. Not specifically related to the HR500, his PTT line floats at 8V which could damage the keying output of the IC705 which is only rated at 5.5V. Dead ICOM.

As a person who designs amplifiers I can tell you that the switching scheme is carefully designed and closely coupled to the processor in the amp. If you decide to start making adjustments be prepared to replace MOSFETs.

73,

Jim WA2EUJ

[AC1I]

In my circumstance I have a HR-500 and a HR-50+ that are capable of operating in parallel, the HR-50+ being used solely for 6M, and the HR-500 for everything else. The PTT signal was being routed between the amps via a SN74HC00. The 5V for the IC was from an internal power supply, the ground common. Most of the time everything was working fine, but after perhaps 20 operations you would fail to hear the relays release on the HR-500 and afterward the HR-500 would not amplify, but it would recognize PTT transitions. Quickly toggling the PTT cleared the condition.

I thought that perhaps I had a sticking relay, but replacement of that relay did not remedy the problem. Direct connection of the IC-705 to the HR-500 did not exhibit this issue, so I replaced the SN74HC00 with a relay, and it has been solid ever since.

I suspect that this issue is related to TTL low level, as seen by the HR-500 not being near enough to ground level, and I was just on the edge of the detection threshold. It would seem to be related to the software, as the PTT assertion is indicated, but not acted upon. Perhaps there was some ringing in the PTT signal, I never did put a scope on it. The HR-50+ never displayed any issued with the PTT.

Patrick AC1I

[Adrian Scripcă YO6SSW]

Hi Geert Jan.

I'd like to add some small information regarding the firmware. Following an email discussion with Jim and you, I got a hold on the sources and decided to go my way and hack at them. First thing I did was to migrate the project to PlatformIO since I wanted to use more potent IDEs (CLion, VS Code) which would help me to refactor things easily.

After the project compiled from my IDE of choice (PlatformIO based), I started heavily refactoring the code, reverse engineering and extracting abstractions from the code to make it easier to understand.

During that time I also grew tired of the slow firmware update process and I added a HW mod which would allow direct programming from the PC.

After that I noticed I had an elevated noise floor in 30M when the amp was running so I hunted that down for a while and managed to tame it by putting the mcu to sleep. There is still a lot of work I want to add but I've broken by left arm falling from a stupid electric scooter and I'm waiting for it to mend. 

One more thing I did was to work on the display speed. I ended up finding the display datasheet and rewriting the video driver a bit. You can see the result here https://www.youtube.com/watch?v=UN1pEMEVmiQ

If Jim allows it, I am sure we can turn this into a community driven firmware.

73 de Adrian

YO6SSW

[Andrew Catanzaro]

Jim, thank you for the info.  If only 100% of what CW i send would be amplified by the HR-500 that would be great!  I guess it's close enough.

73 - Andy W9NJY 

[Robert Cheek]

Interesting Thread.  I like the video driver improvements....looking forward to seeing that implemented.

What I am experiencing driving the HR 500 with a Elad FDM-DUO SDR transceiver is that using CW controlled by the VOX on the Elad, a very short drop of PTT (i.e. between words) the Amp doesn't come back up, it appears to be in bypass.  These drops of the PTT line are less than a second, but I haven't measured them.  I can hear on the RX, so I am pretty sure the amp has gone fully into bypass, but then the next characters sent are at exciter power levels as confirmed on the LP-500 Digital Station Monitor.  I am using the Hobby PCB HR50 interface for the Elad

I am going to try my FT-817 and see if I have the same issue on the different interface.  I will also try to measure the minimum drop that will cause this issue. 

Has anyone else experienced this?

Bob - N4RFC

[Andrew Catanzaro]

Yes, I've experienced the HR 500 dropping out between CW words and not picking up for a second or two of sending.  I've also experienced mid-sentence dropouts on SSB.  This is with using an Icom 705 and with an Elecraft KX3 regardless of how much hang time I program into these radios.  I mostly fixed it by bypassing the HobbyPCB 705 interface and connecting a direct PTT line from the transceiver to the amp's PTT input.  Same with the KX3.  I still experience dropouts in between CW words (25 WPM and above ) but they are less common now.   This is why I got excited about Phil Salas's QST project for a QSK module that would completely bypass the T-R system in the HR 500.  (And besides that I do like to run full QSK.)  But, per Jim's description in this thread, Phil's proposed solution is not a good idea for the HR 500.  BTW I can see the dropouts on the LP-100A SWR meter I have on the output of the HR 500.  Its response time to the amp's output is instantaneous every time.  The built-in power meter on the amp responds too slowly and is not a reliable way to observe the drop out phenomenon.   Also, people I contact sometimes tell me of the dropouts.  

Andy W9NJY

Milwaukee