Astro Spectra UHF Range two conversion UPDATE *MODIFIED VCO*

[jmr061]

Well folks this is what I started off with:

15 watt motorcycle range 2 uhf analog spectra drawer unit
Astro specra 110 watt "Q" range 1 drawer unit

I took the vco and front end receiver out of the analog spectra unit and put it in the astro spectra range 1 drawer unit. I immediately noticed the analog spectra range two VCO had a COAX line running off of it that went to the analog RF board. There was a coax jack on the middle of the analog RF board that was not present on the astro RF board. The astro range 1 vco did not have any coax coming off of it.

Through some research I found that the analog motorcycle RF board is a CEPT board that has something to do with european radios. It is part #HRN6012. I was told the RF board in astros is the same for all UHF ranges. It is part #HRN6020. Now Motorola made TWO types of range two UHF radios. Both are "low" power but one is a motorcycle radio the other is standard. The motorcycle astro uses HRN4010 RF board while the standard range 2 uhf uses HRN6020.

The hi power astro range 1 has the HRN6020 RF board in it. The codeplug I was able to get is from an astro range 2 MOTORCYCLE radio. Well I assembled the parts into the hi power drawer and left the coax coming from the VCO unplugged since the HRN6020 RF board doesn't have the extra coax jack in the middle (there is a spot there for it but it isnt there). Well the radio went into fail 001. So I reassembled everything into the low power drawer and same result, fail 001. Well I figured the fail had something to do with coax coming from the VCO.

After examining the schematics for awhile I decided to remove the extra jack from the analog RF board and put it on the astro RF board. I removed a jumper from the astro RF board that is not present on the analog board.

This was first assembled in the low power drawer unit. Powered it up and no fail code. Keyed up a couple of local ham repeaters and talked to someone on them. Said I sounded just fine. Receive seemed ok.

Switch everything into the hi power drawer unit. Same person said I sounded fine on transmit however there was a noticeable drop in the quality of the receive signal.

This is all done without a service monitor so far. Obvisouly if I get this to the point I want to I will be having it calibrated with a service monitor.

So the next step is for someone to come up with a non motorcycle range 2 uhf codeplug for me and I will see if the the HRN6020 RF board will work without any modifications.

Jason

[jmr061]

I have done some more playing. I un-did the mod I had done to the astro HRN6020 RF board so it is back to "stock" now.

I did several mods to the analog motorcycle VCO: removing the coax jumper that went to the rf board, removing the chip cap(C5636) at pin 1 of the vco and adding a chip jumper at JU5681 on the top side of the vco.

It locks and seems to work fine. Time to take it in to have it tuned up on a service monitor.

Jason