Re-crystaling a UHF HT90

[Purpleman]

I have acquired 6 UHF 4-Watt HT90s, and I am looking to make one or more of these work on Amateur 440 MHz and/or GMRS. I have the Service Manual, and access to most of the eauipment needed to do the alignment (maybe not the audio oscillator for deviation adjusment). I have read these boards, and others, and I understand that this is a losing proposition from a monetary standpoint...but I would be doing it more for the hobby aspect. Given that, I have a few questions.

1. I understand the formulas to get the crystal frequencies, but what other info do I need to order one? For example, what is the hc size, what overtone, what level of accuracy/stabilty, do I need new compensating capacitors, etc. Apparently I can live with the existing 21.855 MHz 2nd LO crystal.

2. They all have the DPL decks. I either would not want to use them by simply not going past the squelch detent, but I will need the regular PL tone board and plug for either the ham or GMRS repeater that I would like to access. I think I have a source for the deck and the plug, would this be a "simple" matter of soldering/unsoldering per the wires listed in the manual? In your experience, is there any adjustment needed?

Thanks

[Jim202]

I have acquired 6 UHF 4-Watt HT90s, and I am looking to make one or more of these work on Amateur 440 MHz and/or GMRS. I have the Service Manual, and access to most of the eauipment needed to do the alignment (maybe not the audio oscillator for deviation adjusment). I have read these boards, and others, and I understand that this is a losing proposition from a monetary standpoint...but I would be doing it more for the hobby aspect. Given that, I have a few questions.

1. I understand the formulas to get the crystal frequencies, but what other info do I need to order one? For example, what is the hc size, what overtone, what level of accuracy/stabilty, do I need new compensating capacitors, etc. Apparently I can live with the existing 21.855 MHz 2nd LO crystal.

2. They all have the DPL decks. I either would not want to use them by simply not going past the squelch detent, but I will need the regular PL tone board and plug for either the ham or GMRS repeater that I would like to access. I think I have a source for the deck and the plug, would this be a "simple" matter of soldering/unsoldering per the wires listed in the manual? In your experience, is there any adjustment needed?

Thanks

Go pick a crystal company and call them. Tell them what radio your using and what operating frequency you will want the radio to operate on. For the most part the crystal company will do the rest.

It has been so long since I was inside one of those radios, I can't remember if there is a crystal holder or if those crystals solder directly to the circuit board. The crystal company should be able to advise you.

Do not get rush service on the crystal delivery. If you do, you will be sorry, as the crystals will walk around in frequency over time. Take normal delivery and just wait the 2 weeks or so it takes. Otherwise you will be forever adjusting or correcting the crystal frequency.

Jim

[kb4mdz]

Solder in.

Make sure you re-use the little plastic pads underneath the crystals. If they're missing, make something out of maybe the area right next to the seam of a Ziplock baggie;

Good Luck!

[Will]

Very good Jim. but need to mention the GOOD crystal makers so the OP gets the correct crystals.
International Crystal in Oklahoma.
Bomar Crystal in New Jersey

I recrystaled a lot of HT90's in my days at Motorola.

[

Go pick a crystal company and call them. Tell them what radio your using and what operating frequency you will want the radio to operate on. For the most part the crystal company will do the rest.

It has been so long since I was inside one of those radios, I can't remember if there is a crystal holder or if those crystals solder directly to the circuit board. The crystal company should be able to advise you.

Do not get rush service on the crystal delivery. If you do, you will be sorry, as the crystals will walk around in frequency over time. Take normal delivery and just wait the 2 weeks or so it takes. Otherwise you will be forever adjusting or correcting the crystal frequency.

Jim

[Purpleman]

Thanks for the info guys. I was going to try Bomar for the crystals.
I just read that the receiver has only a 1 MHz bandwidth...not a problem if I go GMRS, but I guess
a repeater output at 443.xxx on F1 and (say) 446.00 simplex F2 would be a problem?

[Satelite]

Hello:
I totally agree with WILL on ICM or Bomar for the crystals.
I have tried JAN and the Electronic Technological Lab cystals and regretted it years back.
But International Crystal Manufacturing and Bomar crystals served me well.
I don't think ETL is even in biz anymore and not sure about JAN crystal but id steer clear and highly recommend ICM or Bomar.
ICM in Oklahoma last I knew was 1-800-725-1426
I ordered a set of repeater crystals from ICM in 2003 per my records and those crystals were still working when the repeater was removed to upgrade per the narrow band ruling the 1st of 2013.
So they ran and were still operating 10 yrs later until it was replaced to be compliant with narrow band ruling .
I also had ICM do a micor rx and tx element rebuild with the ICM crystal and it too worked very well.
I didn't order a lot of Bomar crystals as I did ICM for some reason but it wasn't due to troubles with Bomar and I for what ever reason just went to ICM out of habit .
ICM might have had a better pricing or delivery was better I don't recall but id be more than happy with either myself.
Satelite

[fineshot1]

I have been using Bomar for many years, probably about 30 years now without any anomalous incidents.
In that time i had used ICM several times also without any trouble.