HW-2036-A synth lock

[Robert Groh]

Could be a number of things - I am not an expert in the 2036A but have a goodly number of years engineering synthesized radios so here are my comments for what they're worth.

First I hope you have a manual, schematic, parts layout, etc and at least a voltmeter and a tuning tool available. The tuning and trouble shooting section will be a big help.

One of the primary (and easiest things to correct) reasons might be that the VCO has drifted, over time, so it is no longer can tune to the operating frequency on transmit. Look at the loop lock voltage when going into transmit - you are probably high or low.  Try some different frequencies and see it is always high or low.  For example, if it tunes at low frequencies and, as you go higher, the lock voltage goes higher and then hits maximum then you probably need to tweak the vco tuning to bring it in back in range.

I believe the same VCO is used on transmit and receive and that a fixed offset is put in to move from one to the other - this 'offset' mechanism may also be faulty.  Again not having a manual available, I'm a bit limited as to my explicit knowledge here.

As to the transmitter cutting off, that is exactly what should happen.  Per FCC rules (and common sense!), you should never transmit on an illegal frequency.  Hence a synthesized radio is always (or should be always) equipped  to cut the transmitter is the synthesizer is not in lock.

Hope this helps.

73
Bob Groh, WA2CY






________________________________
From: Kenth B Astrom <kenth at TOTOKET.COM>
To: HEATH at LISTS.TEMPE.GOV
Sent: Saturday, April 18, 2009 7:37:28 PM
Subject: [HEATH-TEMPE] HW-2036-A synth lock

Gang,

I have a HW-2036-A which has been working flawlessly for a few years,

It has now started to refuse to lock the synthersizer when transmitting -
the only thing that happens is the red LED for "LOCK" comes on red, and
won't go green i.e. locking.

I first came across this when chatting as usual on the repeater and when
handing over, there was no longer anyone at 'the other end', so it is clear
that when this happens, it in some way cuts the output down to nothing.

Any ideas anyone?

Thanks in advance.

73 de W1JKP / Kenth

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