URC-200 ISsues

[BondTech]

Good Morning!

I just obtained a nice URC-200 that transmits per spec but the receiver has an issue. The sensitivity is per spec on the 10 frequencies
listed in the manual for performance testing but once programmed off of these frequencies it is stone deaf - like 1000uV even does not get through. Any help would be much appreciated. Also, are schematics available somewhere?

 

[K4EET]

Good Morning!

I just obtained a nice URC-200 that transmits per spec but the receiver has an issue. The sensitivity is per spec on the 10 frequencies
listed in the manual for performance testing but once programmed off of these frequencies it is stone deaf - like 1000uV even does not get through. Any help would be much appreciated. Also, are schematics available somewhere?

Welcome to Radio Reference!

My first question would be what frequencies are you trying to program that are “stone deaf” on receive?

 

[K4EET]

Here is the Operation and Maintenance Manual for a General Dynamics URC-200 (Version 2) VHF Transceiver:

https://www.manualslib.com/products/General-Dynamics-Urc-200-V2-13314404.html

That should have the information that you are looking for.

 

[AM909]

You're sure you have the correct modulation (AM or FM) and bandwidth programmed? Does it transmit on-frequency?

 

[BondTech]

Thanks for the replies!

I have read through the GD Manual. Unfortunately, it does not contain schematics. The 10 frequencies I mentioned are those the manual says to program into the radio for testing.

It is not in Aviation Mode and both the radio and signal generator were programmed for AM for FM Modes as appropriate.

The transmitter checks out using my AMM2002Q Modulation Analyzer (frequency, modulation percentage/bandwidth, distortion & power) It also draws the specified currents for both receive and transmit (internal readings were verified using an Agilent DMM).

Again, thanks for the comments!

 

[K4EET]

<snip> The sensitivity is per spec on the 10 frequencies
listed in the manual for performance testing but once programmed off of these frequencies it is stone deaf - like 1000uV even does not get through. <snip>

<snip> My first question would be what frequencies are you trying to program that are “stone deaf” on receive?

The desired frequencies you want to use that are not the ten frequencies that are listed in the manual, are they in the same sub-band? Based on the model number and any included options, are your desired frequencies within the operational sub-band that your General Dynamics URC-200 is configured for? It is odd that the “factory frequencies” function properly per specs for both transmit and receive, your desired transmit frequencies all function properly per specs, but all of your desired receive frequencies are “stone deaf” not even “hearing” a 1,000uV input signal.

Out of curiosity, what kind of readings are you getting on your Wayne Kerr AMM2002Q Modulation Analyzer for other receive frequencies between one of the ten receive frequencies that is within spec and one of your desired receive frequencies that is “stone deaf”? Through that range, take ten to twenty test frequencies, equally spaced, to see what a signal level versus frequency plot looks like. This may shed some light on what is causing your desired receive frequencies to be “stone deaf”. Worth a shot…

 

[BondTech]

Thanks, I'll do that. BTW - Do you or anyone else have leads on obtaining schematics?

 

[K4EET]

Thanks, I'll do that. BTW - Do you or anyone else have leads on obtaining schematics?

You're welcome!

As for the schematic(s), that seems to be a well-kept secret. One thing that you might try is to contact General Dynamics at

8220 E Roosevelt Rd​

Scottsdale, AZ 85257​

to see if somebody may be able to help you out.

If you cannot find a Scottsdale, Arizona telephone number for them, you might try their Headquarters in Virginia.

General Dynamics Mission Systems Headquarters​

15036 Conference Center Drive​

Chantilly, VA 20151​

tel: 1-877-449-0600​

 

[AM909]

I have read through the GD Manual. Unfortunately, it does not contain schematics. The 10 frequencies I mentioned are those the manual says to program into the radio for testing.

Where in the manual?

At what freq and mode is it deaf?

 

[PACNWDude]

Even working for an organization with many URC-200's, GD seems to only talk to those buying the current URC-300 radio. And then, it is like pulling teeth from a chicken. Good luck.